Randomized controlled trial of clarithromycin and ethambutol in the treatment of Crohn's disease.

BACKGROUND: A mycobacterial infection may be the cause of Crohn's disease in some patients. Measurement of intestinal permeability may identify Crohn's disease patients with a high likelihood of relapse and may quantify the severity of intestinal injury. AIM: To assess the effect of 3 months of clarithromycin and ethambutol on the disease activity and intestinal permeability in patients with Crohn's disease at high risk of relapse. METHODS: Patients with Crohn's disease, with a lactulose-mannitol permeability test above 0.03, were randomly assigned to receive either clarithromycin, 500 mg twice daily, and ethambutol, 15 mg/kg daily, or identically appearing placebo for 3 months in addition to their regular therapy. The Harvey-Bradshaw index and the lactulose-mannitol test were assessed in a blind fashion every 3 months for 12 months. RESULTS: Thirty-one patients were randomized to receive either drugs (n=15) or placebo (n=16). The groups were similar in age, sex, duration of disease, location of disease, past complications and disease severity. Specifically, there was no difference between the drug or placebo groups in the mean Harvey-Bradshaw index (4.8 vs. 4.4), number with active disease (33% vs. 44%) and mean lactulose-mannitol test (0.06 vs. 0.10). During the 12-month follow-up period, there were no consistent, statistically significant differences in the mean Harvey-Bradshaw index or lactulose-mannitol test between treatment and placebo groups. Individual patients showed either improvement or worsening of these indices, but these were not related to study medication. Specifically, no 'cures' were noted with anti-mycobacterial treatment. CONCLUSIONS: Three months of treatment with clarithromycin and ethambutol does not benefit Crohn's disease patients who are receiving standard medical therapy.

Diagnosis of hemoglobinopathies: electrophoresis vs. HPLC.

BACKGROUND: Alkaline cellulose acetate and acidic citrate agar electrophoreses are the most widely utilized methods for hemoglobin analysis. However, due to their limited resolution, incorrect or unresolved diagnosis of common hemoglobinopathies are sometimes encountered. METHODS: Isoelectric focusing provides excellent resolution but is labor intensive and lacks accurate quantitation. High-performance liquid chromatographic methods have been developed for either screening or confirmation of hemoglobinopathies with relatively high sensitivity or specificity. Through the years, we have developed, refined and optimized an HPLC procedure using a porous silica coated with polyaspartic acid to improve the elution time of hemoglobin analysis while maintaining the high sensitivity and resolution necessary for both screening and confirmatory purposes. RESULTS: The method is capable of separating more than 45 commonly encountered hemoglobin variants within 12 min. These include Barts, H, A1C, Raleigh, Hope, I, F, Camden, N-Baltimore, I-High Wycombe, I-Paris, J-Baltimore, N-Seattle, Grade, Fannin-Lubbock, Malmo, South Florida, A, Chicago, G-Georgia, Lepore-Baltimore, P-Galveston, G-Coushatta, Lepore-Boston, E, Zurich, Osu Christiansborg, A2, G-Philadelphia, Korle Bu, Russ, E-Saskatoon, Richmond, D-Punjab, Deer Lodge, Koln, Montgomery, S, Q-Thailand, G-San Jose, A2', Hasharon, Q-India, Tampa, Constant Spring, SG-hybrid, C-Harlem, O-Arab, British Columbia, and C. The method provides not only the identification of the aforementioned hemoglobin and variants but also an accurate quantitation of their concentrations, particularly Hb F and A2, which are useful for the diagnosis of HPFH and beta-thalassemia, respectively. CONCLUSIONS: The simplicity of the sample preparation, superior resolution of the method, and accurate quantitation of hemoglobin concentration, combined with complete automation, make this an ideal methodology for the routine diagnosis of hemoglobin disorders in a clinical laboratory.

Gamma-glutamyl transpeptidase-deficient mice are resistant to the nephrotoxic effects of cisplatin.

We have proposed that the nephrotoxicity of cisplatin, a widely used chemotherapy drug, is the result of the binding of cisplatin to glutathione and the subsequent metabolism of the cisplatin-glutathione complex via a gamma-glutamyl transpeptidase (GGT)-dependent pathway in the proximal tubules. To test the hypothesis that GGT activity is essential for the nephrotoxicity of cisplatin, the effects of cisplatin were examined in wild-type and GGT-deficient mice. Mice were treated with 15 mg cisplatin/kg. Five days after treatment, renal histopathology, blood urea nitrogen levels, serum creatinine, platinum excretion, and platinum accumulation in the kidney were examined. Half the mice were supplemented with N-acetylcysteine, which has been shown to correct low levels of tissue glutathione in GGT-deficient mice. The data show that cisplatin was nephrotoxic in wild-type mice but not in GGT-deficient mice. The wild-type mice, with and without N-acetylcysteine supplementation, had significantly elevated levels of blood urea nitrogen, serum creatinine, and renal tubular necrosis. There was no evidence of nephrotoxicity in the GGT-deficient mice regardless of N-acetyl cysteine supplementation. No differences in platinum excretion were seen comparing wild-type and GGT-deficient mice, nor was there any significant difference in renal platinum accumulation. These data suggest that renal cisplatin toxicity is dependent on GGT activity, and is not correlated with uptake. The results support our hypothesis that the nephrotoxicity of cisplatin is the result of the metabolism of the drug through a GGT-dependent pathway.

Characterization of glycated hemoglobin in diabetic patients: usefulness of electrospray mass spectrometry in monitoring the extent and distribution of glycation.

A combination of chromatographic and mass spectrometric techniques was used to evaluate the extent and distribution of glycation within the glycated hemoglobin (GHb) molecule. Studies on quantification of hemoglobin (Hb) glycation by electrospray ionization mass spectrometry (ES-MS) of intact globins employed specimens from 10 diabetic individuals and five normal controls. Detailed structural analysis of the phenylboronate affinity chromatography/ion-exchange (IE) HPLC-separated sub-populations of GHb was performed on a specimen carrying 13.7% GHb. An efficient protocol for mapping glycation sites within alpha and beta globins was developed, e.g., Glu-C/Asp-N proteolytic digestion followed by LC-ES-MS. Relative site occupancy within discrete components of GHb was evaluated. A correlation between the degree of glycation measured at Hb level (by affinity chromatography) and at globin level (measured by ES-MS) was carried out. The above studies led us to conclude that during the process of phenylboronate chromatography GHb dimers, rather than tetramers, are bound to the affinity resin so a fraction of glycated dimers rather than tetramers is measured. This finding implies that a process of glycation affects a much higher number of native Hb tetramers than was previously contemplated. No glycation sites appear to be missed by phenylboronate affinity chromatography. We have found no evidence of the presence of multiple glycations within a single globin chain. While glycation of both globins within a dimer cannot be excluded, it is unlikely to be a significant phenomenon. According to ES-MS data, an equivalent of about one globin per alphabeta dimer of the affinity chromatography-isolated GHb carried glycation.

Dach1 mutant mice bear no gross abnormalities in eye, limb, and brain development and exhibit postnatal lethality.

Drosophila dachshund is necessary and sufficient for compound eye development and is required for normal leg and brain development. A mouse homologue of dachshund, Dach1, is expressed in the developing retina and limbs, suggesting functional conservation of this gene. We have generated a loss-of-function mutation in Dach1 that results in the abrogation of the wild-type RNA and protein expression pattern in embryos. Homozygous mutants survive to birth but exhibit postnatal lethality associated with a failure to suckle, cyanosis, and respiratory distress. The heart, lungs, kidneys, liver, and skeleton were examined to identify factors involved in postnatal lethality, but these organs appeared to be normal. In addition, blood chemistry tests failed to reveal differences that might explain the lethal phenotype. Gross examination and histological analyses of newborn eyes, limbs, and brains revealed no detectable abnormalities. Since Dach1 mutants die shortly after birth, it remains possible that Dach1 is required for postnatal development of these structures. Alternatively, an additional Dach homologue may functionally compensate for Dach1 loss of function.

Oxygen-induced pulmonary injury in gamma-glutamyl transpeptidase-deficient mice.

We used mice with a targeted disruption in g-glutamyl transpeptidase (GGT-deficient mice) to study the role of glutathione (GSH) in protection against oxygen-induced lung injury. These mice had reduced levels of lung GSH and restricted ability to synthesize GSH because of low levels of cysteine. When GGT-deficient mice were exposed to 80% oxygen, they developed diffuse pulmonary injury and died within eight days. Ten of 12 wild-type mice were alive after 18 days. Administration of N-acetylcysteine (NAC) to GGT-deficient mice corrected GSH values and prevented the development of severe pulmonary injury and death. Oxygen exposure induced an increase in lung GSH levels in both wild-type and GGT-deficient mice, but induced levels in the mutant mice were <50% of those in wild-type mice. Cysteine levels were approximately 50-fold lower than GSH levels the lungs of both wild-type and GGT-deficient mice. Levels of lung RNA coding for the heavy subunit of g-glutamyl cysteine synthetase rose three- to fourfold after oxygen exposure in both wild-type and GGT-deficient mice. In contrast, oxygen exposure failed to provoke increases in glutathione synthetase, glutathione peroxidase, glutaredoxin, or thioredoxin.

Cataract development in gamma-glutamyl transpeptidase-deficient mice.

The present study was undertaken to analyse the relationship of lens glutathione (GSH) and light to cataract development in mice deficient in gamma-glutamyl transpeptidase (GGT). These mice have reduced levels of cysteine and GSH in the eye and develop cataracts. GGT-deficient mice raised under normal vivarium conditions, showed no cataractous changes at birth, but by 1 week they had developed nuclear opacities. By 3 weeks more severe cataracts develop, and lens GSH levels are approximately 6-7% of wild type levels. By 6-11 weeks cataracts show nuclear and cortical involvement, liquefaction and calcification. Single cell DNA electrophoresis (comet assay) demonstrated mild DNA damage in the lens epithelium. GGT-deficient mice raised in the dark beginning the day after conception all developed cataracts, but these were less severe than those in GGT-deficient mice raised with normal vivarium lighting. Administration of N -acetyl cysteine (NAC) raises lens GSH and almost completely prevents cataract development. Our data indicate that cataract development in GGT-deficient mice is multifactorial and results from exogenous damage (exposure to light), reduced lens GSH levels, and nutritional effects secondary to low cysteine levels.

Elevated expression of hepatic proliferative markers during early hepatocarcinogenesis in hepatitis-B virus transgenic mice lacking mdr1a-encoded P-glycoprotein.

Recent studies have shown that expression levels of the multidrug resistance gene MDR1, which encodes the drug transporter P-glycoprotein, correlate with prognostic outcomes of certain tumor types. These findings suggest that expression of MDR1 may affect tumor behaviors. To address this issue further, we investigated the expression of mdr1a, a human MDR1 homolog, on the development of hepatocellular carcinoma in a transgenic mouse model carrying the liver-targeted expression of human hepatitis-B virus (HBV) surface antigen. The pathogenetic program was compared in HBV mice carrying either mdr1a(+/+) or mdr1a(-/-). We found that the expressions of proliferative activity markers, Ki67 nuclear antigen, and proliferating cell nuclear antigen were elevated in mdr1a(-/-) mice younger than 10 wk in comparison with those in the same age group of wild-type animals. Replication in the hepatic population as determined by bromodeoxyuridine incorporation tended to support observation that mdr1a(-/-) mice exhibited elevated labeling indices in this age group. Moreover, histologic staining and flow-cytometric analysis showed that the mdr1a(-/-) animals exhibited a higher cell population with polyploidy than did the mdr1a(+/+) counterparts of the same age. However, no significant differences in the expression of the liver-injury markers serum alanine transaminase and aspartate transaminase were observed. Although our results showed that absence of mdr1a expression is correlated with modest enhanced proliferative characteristics in the livers at stage before the development of hepatocellular carcinoma, the overall life spans between these two strains of mice were not significantly different. The implication of these findings to the role of P-glycoprotein in tumor development and cancer chemotherapy is discussed.

Altered gene expression in the liver of gamma-glutamyl transpeptidase-deficient mice.

We used mice deficient in gamma-glutamyl transpeptidase (GGT) to analyze the effects of GGT deficiency and altered thiol levels on gene expression in liver. GGT-deficient mice have markedly reduced levels of glutathione (GSH), cysteine, methionine, and cysteinylglycine in liver. Steady-state RNA levels of the catalytic subunit of gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme in GSH synthesis, are elevated 4-fold in these mice, while those for glutathione synthetase (GSH syn) are elevated 2-fold. RNA levels of cystathionase (cystathionine gamma-lyase), a key enzyme in the synthesis of cysteine from methionine, are elevated approximately 3.5-fold. In contrast, levels of RNA coding for multidrug resistance protein 2 (MRP2), which transports GSH into bile, are half wild-type values. We found no change in RNA levels of enzymes related to oxidative injury (CuZn and Mn superoxide dismutases [SOD], catalase, and glutathione peroxidase). Similarly, RNA levels of glutathione reductase and ribonucleotide reductase were unchanged. Furthermore, in contrast to previous in vitro results, methyl methanesulfonate did not induce stress-activated signal transduction as measured by c-jun phosphorylation in livers of GGT-deficient mice, despite further depletion of GSH by buthionine sulfoximine. Our findings indicate that GGT deficiency itself and/or altered thiol levels regulate expression of genes involved in GSH metabolism, but have no effect on the expression of other antioxidant genes.

Genetic correction of sickle cell disease: insights using transgenic mouse models.

Sickle cell disease is a hereditary disorder characterized by erythrocyte deformity due to hemoglobin polymerization. We assessed in vivo the potential curative threshold of fetal hemoglobin in the SAD transgenic mouse model of sickle cell disease using mating with mice expressing the human fetal Agamma-globin gene. With increasing levels of HbF, AgammaSAD mice showed considerable improvement in all hematologic parameters, morphopathologic features and life span/survival. We established the direct therapeutic effect of fetal hemoglobin on sickle cell disease and demonstrated correction by increasing fetal hemoglobin to about 9-16% in this mouse model. This in vivo study emphasizes the potential of the SAD mouse models for quantitative analysis of gene therapy approaches.

The effect of arginine or glycine supplementation on gastrointestinal function, muscle injury, serum amino acid concentrations and performance during a marathon run.

Gastrointestinal bleeding and increased intestinal permeability have been observed in marathon runners. We sought to determine if L-arginine would be useful for prevention of these complications. Twenty-three runners were randomized to receive L-arginine (A) or glycine (placebo) (G), 10 grams 3 times daily for 14 days prior to the 1997 Houston-Methodist Marathon. Serum, stool hemoccults and lactulose:mannitol permeabilities were obtained at baseline, immediately after completion of the marathon and approximately 48 hours later. Runners rated their symptoms of nausea and vomiting, belching and indigestion, abdominal pain and bloating, diarrhea, and extremity pain on a 1-5 scale of increasing severity. The L:M was unchanged in either group during the three collections. Occult bleeding occurred in 8%/20% in A and G groups, respectively, p = NS) immediately post-marathon. No runners had occult bleeding 48 hours post-race. Gastrointestinal symptom scores were minimal to nonexistent. Extremity pain scores were similar for groups A and G (2.1+/-1.4 and 2.8+/-1.6, respectively, (p = NS). Fluid intake was similar between both groups (1875+/-1547 vs. 1506+/-970 ml, p = NS). Serum amylase was normal at baseline and remained virtually unchanged. Serum lipase was normal at baseline and immediately post-race in both groups, but increased at 48 hours post-race (82.2+/-34.3 to 121.5+/-53.3 mg/dl [A], p = 0.02 and 114.3+/-55.7 to 181.9+/-162.2 mg/dl [G], p = 0.09). CPK increased significantly and similarly in both groups immediately post-race, and even more dramatically 48 hours post-race (130.3+/-130.8 to 738.8+/-902.9, p = 0.007 to 1966.5+/-3.166.0 mg/dl [A] and 140.9+/-77.9 to 863.0+/-772.3, p = 0.003 to 5619+/-10636.8mg/dl [G]). Modest post-race decreases were seen in most serum amino acids in both groups. Finish times were longer than predicted (23+/-21 and 9+/-7 min for A and G groups, respectively, p = 0.049). Our study failed to show a clear benefit of arginine supplementation for the prevention of intestinal ischemia/reperfusion injury associated with endurance running, but either a detrimental affect on performance with arginine, or enhanced performance with glycine. Skeletal muscle injury was unaffected by arginine or glycine supplementation. The delayed increase in serum lipase suggests mild pancreatic injury, affected by either arginine or glycine supplementation.

Evaluation of a real-time blood glucose monitor in children with diabetic ketoacidosis.

Use of a real-time bedside glucose monitor was analyzed during the course of management of diabetic ketoacidosis (DKA) in children. Simultaneous determinations of blood glucose were obtained, using three methods: bedside glucose meter (One Touch II), laboratory glucose analyzer (YSI 2300 STAT), and a real-time bedside glucose monitor (VIA 1-01G Blood Chemistry monitor). Study patients included seventeen patients < 18 years of age admitted to a Pediatric Intensive Care Unit, with blood samples obtained during treatment of DKA by continuous insulin infusion. Four patients did not complete the study. Three experienced temporary technical problems with the monitor, and four required repeat IV placement. Duration of monitor use ranged between 6 and 47 h (mean 24 +/- 4 h). Blood glucose values ranged between 2.6 and 22.5 mmol/l. Overall correlation of blood glucose values were as follows: 0.965, 0.965, 0.973, VIA 1-01G vs. One Touch II, VIA 1-01G vs. YSI 2300 STAT, and One Touch II vs. YSI 2300 STAT, respectively (all P-values < 0.0001). This real-time bedside glucose monitor is accurate at glucose values < 13.8 mmol/l, and reliable for rapid, repetitive analyses. Results indicate that blood glucose values obtained using this real-time monitor are comparable to those using standard methods of measurement, and that this device is clinically applicable for use in management of children with DKA.

Simulated airplane flight increases plasma lactate in fetal rabbits.

We studied the effect of 9 h of simulated airplane cabin conditions at cruising altitude (8,000 feet; inspired oxygen equivalent to 15% O2 at sea level) on fetal plasma lactate in near-term pregnant rabbits. Controls (n = 19) spent 9 h at sea level (21% O2). Study group I (n = 21) experienced airplane cabin conditions. Study group II (n = 17) was studied at 8,000 feet with the inspired O2 concentration normalized to sea level. Study group III (n = 19) remained at sea level breathing 15% O2. Before ending each exposure, fetal blood sampling for lactate was performed under ultrasound guidance. Maternal lactates were obtained before and after sampling fetuses. Wilcoxon signed rank test, analysis of variance, and Bonferroni's method were used as appropriate. P < 0.05 denoted statistical significance. Study group I (altitude/hypoxia) had higher fetal lactates than controls (sea level/normoxia) and study group II (altitude/normoxia). Fetal lactates in study group I (altitude/hypoxia) were higher than in study group III (sea level/hypoxia). Maternal lactates were lower after fetal sampling. Fetal lactic acidemia was observed after 9 h of airplane cabin conditions. This was attributed to the combined effect of the lowered oxygen concentration and the decrease in atmospheric pressure.

Megacystis, mydriasis, and ion channel defect in mice lacking the alpha3 neuronal nicotinic acetylcholine receptor.

The alpha3 subunit of the neuronal nicotinic acetylcholine receptor is widely expressed in autonomic ganglia and in some parts of the brain. The alpha3 subunit can form heteromultimeric ion channels with other alpha subunits and with beta2 and beta4 subunits, but its function in vivo is poorly understood. We prepared a null mutation for the alpha3 gene by deletion of exon 5 and found that homozygous (-/-) mice lacked detectable mRNA on Northern blotting. The -/- mice survive to birth but have impaired growth and increased mortality before and after weaning. The -/- mice have extreme bladder enlargement, dribbling urination, bladder infection, urinary stones, and widely dilated ocular pupils that do not contract in response to light. Detailed histological studies of -/- mice revealed no significant abnormalities in brain or peripheral tissues except urinary bladder, where inflammation was prominent. Ganglion cells and axons were present in bladder and bowel. Bladder strips from -/- mice failed to contract in response to 0.1 mM nicotine, but did contract in response to electrical field stimulation or carbamoylcholine. The number of acetylcholine-activated single-channel currents was severely reduced in the neurons of superior cervical ganglia in -/- mice with five physiologically distinguishable nicotinic acetylcholine receptor subtypes with different conductance and kinetic properties in wild-type mice, all of which were reduced in -/- mice. The findings in the alpha3-null mice suggest that this subunit is an essential component of the nicotinic receptors mediating normal function of the autonomic nervous system. The phenotype in -/- mice may be similar to the rare human genetic disorder of megacystis-microcolon-intestinal hypoperistalsis syndrome.

Short-term vitamin E supplementation before marathon running: a placebo-controlled trial.

Gastrointestinal complaints and occult bleeding have been commonly described in marathon runners. We hypothesized that these complaints may arise from intestinal ischemia caused by the shunting of blood away from the splanchnic circulation during endurance racing followed by reperfusion injury. Studies in animal models have suggested prophylactic vitamin E supplementation may prevent this type of injury. We sought to determine if prerace vitamin E supplementation would prevent intestinal ischemia/reperfusion injury in humans. Forty subjects who planned to complete the 1996 Houston-Tennaco Marathon were randomized to receive vitamin E (1000 IU daily) or placebo (soya lecithin) for 2 wk before the race in a double-blinded trial. Inclusion criteria included no use of non-steroidal anti-inflammatory drugs (NSAIDs) within 24 d of the race or vitamin or mineral supplements containing vitamins C or E or selenium within 30 d of the race. Subjects were studied 2 wk before the race and immediately following the race. Blood was obtained for serum vitamin E and total lipid and salicylate concentrations. A solution of lactulose (5 g) and mannitol (2 g) was consumed and urine was collected for 6 h. Aliquots were assayed for lactulose and mannitol concentration. Stool samples were tested for occult blood and following the race subjects rated their nausea, abdominal pain, and cramping on a 1-5 scale. Twenty-six subjects (24 male, 2 female) completed the marathon. Finish times ranged between 2 h 43 min and 5 h 28 min. All subjects had heme-negative stool prerace and four developed heme-positive stool postrace, with no difference between vitamin E and placebo groups (Fisher's exact = 0.63). All had non-detectable salicylate concentrations pre- and postrace. Serum vitamin E concentration increased in botPP = 0.02 in the vitamin E group and 1.45 +/- 0.40 to 1.66 +/- 0.48 mg/dL in the placebo group, P = 0.02). However, the serum vitamin E: total lipid ratio increased significantly in the vitamin E-supplemented group (0.0022 +/- 0.0002 to 0.0051 +/- 0.0015, P = 0.02), but not in the placebo group (P = 0.25). Overall, the urinary lactulose:mannitol ratio increased from 0.03 +/- 0.02 to 0.06 +/- 0.08 postrace (P = 0.06) without difference between vitamin E or placebo groups. Intestinal permeability increased significantly more in those who developed occult bleeding. More subjects in the placebo group developed abdominal cramping (Fisher's exact = 0.04) and abdominal pain (Fisher's exact = 0.06), although there was no difference in severity between groups. There was no difference in the incidence of nausea and no diarrhea was reported by any subject. Intestinal permeability tends to increase and occult gastrointestinal bleeding occurs during endurance running, suggesting the occurrence of intestinal ischemia/reperfusion injury. Prerace supplementation with the antioxidant vitamin E had no effect on performance, intestinal injury, occult bleeding, or the severity of postrace gastrointestinal complaints. Vitamin E supplementation was associated with a decreased incidence of these complaints but had no effect on their severity.

Pharmacokinetics of ibuprofen in patients with cystic fibrosis.

STUDY OBJECTIVES: To determine the pharmacokinetic disposition of high doses of ibuprofen in patients with cystic fibrosis (CF), and to evaluate the reliability of intrapatient dosage adjustments to achieve recommended peak ibuprofen plasma concentrations. DESIGN: First-order absorption, one-compartment model was fit to serial ibuprofen concentration-time data obtained from patients with CF and receiving high doses of ibuprofen 20-30 mg/kg. SETTING: Medical school-affiliated teaching hospital. PATIENTS: Ninety-eight patients with CF (53 males, 45 females; mean age 12.5 yrs). MEASUREMENTS AND MAIN RESULTS: The time to achieve apparent maximum ibuprofen concentration (Tmax) ranged from 1-3 hours, with maximum concentrations ranging from 21-150 microg/ml (mean 83 microg/ml). Apparent ibuprofen clearance (Cl/F) was significantly correlated with age (r2 = 0.43, p<0.0001) and measures of body size (body surface area [BSA] r2 = 0.50, p<0.0001). The Cl/F ranged from 21.1-114.7 ml/min/m2 (mean 45.5 ml/min/m2), a 5-fold difference. The Cl/F normalized to body weight decreased with increasing age (p=0.0009), but when normalized to BSA, there was no age-related change (p=0.65). Apparent volume of distribution was significantly correlated with age (r2 = 0.69, p<0.0001) and measures of body size (BSA r2 = 0.79, p<0.0001). Fourteen patients had ibuprofen dosage adjustments. The Cl/F was not different among doses; however, Tmax differed by an average of 1.25 hours (range 0-2 hrs). CONCLUSION: The substantial variability in ibuprofen disposition and clearance we report is greater than previously described. Individualized dosages and therapeutic drug monitoring may be required to ensure plasma concentrations considered necessary to prevent pulmonary deterioration in patients with CF.

Ferritin, transferrin and iron concentrations in the cerebrospinal fluid of multiple sclerosis patients.

The concentrations of ferritin, transferrin and iron were measured in the cerebrospinal fluid (CSF) of multiple sclerosis (MS) and control patients. Ferritin levels were significantly elevated in the CSF of chronic progressive active MS patients (4.71+/-0.54 ng/ml) compared to levels in normal individuals (3.07+/-0.17 ng/ml). MS patients with active or stable relapsing-remitting disease had ferritin levels that were comparable to those found in normal individuals. There were no significant differences in transferrin or iron levels in the CSF between MS and normal individuals. Both ferritin and transferrin levels were elevated in patients that had high CSF IgG values but not in patients with a high IgG index. Since ferritin binds iron, the increase of CSF ferritin levels in chronic progressive MS patients could be a defense mechanism to protect against iron induced oxidative injury. Ferritin levels could be a laboratory measure that helps to distinguish between chronic progressive and relapsing-remitting MS.

Cyclosiloxanes produce fatal liver and lung damage in mice.

To examine the toxicity of cyclosiloxanes (CSs), the predominant low molecular weight cyclic silicones found in breast implants, we injected female CD-1 mice intraperitoneally with different doses of distillate (3.5-35 g/kg body weight) containing cyclosiloxane D3 (hexamethylcyclotrisiloxane; CS-D3), cyclosiloxane D4 (octamethylcyclotetrasiloxane; CS-D4), cyclosiloxane D5 (decamethylcyclopentasiloxane; CS-D5), and cyclosiloxane D6 (dodecamethylcyclohexasiloxane; CS-D6). The distillate was found to be lethal and all the mice injected with 35 g/kg died within 5-8 days. The median lethal dose (LD50) for distillate was estimated to be approximately 28 g/kg. These mice developed inflammatory lesions of the lung and liver as well as liver cell necrosis with elevated serum levels of alanine aminotransferase, aspartate aminotransferase, and lactic acid dehydrogenase. Administration of CS-D4 alone also produced lethality in these mice with an LD50 of 6-7 g/kg. CS-D4-treated mice also exhibited pulmonary and hepatic lesions and elevated serum enzymes. Analysis of LD50 data indicates that CS-D4 is about as toxic as carbon tetrachloride or trichloroethylene. We measured hydroxyl radical formation in CS-D4-treated mice and found increases of approximately 20-fold in liver and approximately 7-fold in lung on day 4 following injection. Our findings are significant because in vitro experiments have demonstrated that CSs can migrate out of breast implants, and in mouse experiments CSs have been shown to be widely distributed in many organs after a single subcutaneous injection and to persist for at least a year.

Early feeding, feeding tolerance, and lactase activity in preterm infants.

OBJECTIVE: We sought to ascertain whether the timing of feeding initiation affected the development of intestinal lactase activity and whether there are clinical ramifications of lower lactase activity. STUDY DESIGN: Preterm infants (26 to 30 weeks' gestation; n = 135) were randomly assigned to begin enteral feedings at either 4 (early group) or 15 days of age (standard group). At 10, 28, and 50 days of age lactase activity was determined by measuring the urinary ratio of lactulose/lactose after the 2 sugars were administered. RESULTS: Lactase activity increased significantly over time. Infants in the early group had greater lactase activity at 10 days of age (by 100%) and 28 days of age (by 60%) than the standard group. At 10 days of age lactase activity was greater in milk- versus formula-fed infants. The time required to achieve full enteral feedings, the number of abnormal abdominal x-ray examinations, and the total number of abdominal x-ray examinations were inversely related to lactase activity. CONCLUSIONS: Early feeding increases intestinal lactase activity in preterm infants. Lactase activity is a marker of intestinal maturity and may influence clinical outcomes. Whether the effects of milk on lactase activity were due to the greater concentration of lactose in human milk compared with that in formula must be determined.