Signatures of Quantum-Tunneling Diffusion of Hydrogen Atoms on Water Ice at 10 K.

Reported here is the first observation of the tunneling surface diffusion of a hydrogen (H) atom on water ice. Photostimulated desorption and resonance-enhanced multiphoton ionization methods were used to determine the diffusion rates at 10 K on amorphous solid water and polycrystalline ice. H-atom diffusion on polycrystalline ice was 2 orders of magnitude faster than that of deuterium atoms, indicating the occurrence of tunneling diffusion. Whether diffusion is by tunneling or thermal hopping also depends on the diffusion length of the atoms and the morphology of the surface. Our findings contribute to a better understanding of elementary physicochemical processes of hydrogen on cosmic ice dust.

Pathogenic role of thromboxane A2 in immediate food hypersensitivity reactions in children.

BACKGROUND: Food hypersensitivity, from the standpoint of pathogenesis as well as clinical management, remains controversial. During the food allergen-induced immediate hypersensitivity reaction, various chemical mediators are released. OBJECTIVE: The purpose of our study was to determine whether thromboxane A2 participates in food antigen-induced responses in children with food hypersensitivity. METHODS: Nine open food challenges were performed in nine patients with suspected food hypersensitivity. Plasma thromboxane B2 and histamine levels were measured during a 24-hour period following the challenge. RESULTS: All the patients demonstrated immediate reactions after food challenge. The mean plasma thromboxane B2 level (a marker of thromboxane A2 activity) rose significantly at two hours and three hours after the challenge. Simultaneously, the mean plasma histamine level rose significantly at two hours and three hours after the challenge. CONCLUSIONS: The results suggest that thromboxane A2 may play a pathogenic role in part in the immediate reaction after food challenge and that thromboxane A2 is probably released from a common cellular source (eg, mast cell) with histamine and/or by a common mechanism (eg, IgE-dependent platelet activation).

[Clinical studies on SY5555 in pediatric infections].

Pharmacokinetic and clinical studies on SY5555, a new oral penem antibiotics, were performed in pediatric infections and the following results were obtained. 1. Pharmacokinetics studies Pharmacokinetics of SY5555 was studied in 5 children (5y1m-10y11m) using doses of 5 mg/kg (n = 3) and 10 mg/kg (n = 2). The average peak plasma levels were 0.65 microgram/ml at 1 or 2 hours after administration of 5 mg/kg and 2.12 micrograms/ml at 1 or 2 hours after administration of 10 mg/kg, and the plasma half-lives were 0.81 and 1.08 hours, respectively. Average cumulative urinary recovery rates at 0-6 hours were 2.97 and 3.96%, respectively. 2. Clinical studies SY5555 was administered to 45 patients with various infectious diseases (2 with acute pharyngitis, 8 with acute tonsillitis, 4 with lacunar tonsillitis, 3 each with acute bronchitis, pneumonia and pertussis, 7 with scarlet fever, 3 with impetigo contagiosa, 6 with acute urinary tract infections, 2 with balanoposthitis and 1 each with cervical lymphadenitis, S.S.S.S., vulvitis and acute colitis) at daily doses between 3.4-10 mg/kg, t.i.d., for 3-14 days. Clinical responses were excellent in 27 patients, good in 15 patients, fair in 1 patient, and poor in 2 patients, and the efficacy rate was 93.3%. Causative organisms were examined and 39 strains of 11 species were identified. The eradication rate was 78.9%. Side effects were observed in 1 patient with diarrhea. An abnormal laboratory test value was observed in 1 patient with elevation of eosinophils. The above results suggest that SY5555 may be a very useful and safe drug for the treatment of pediatric infection.

Time course of plasma histamine and tryptase following food challenges in children with suspected food allergy.

This study was undertaken to investigate the kinetics of histamine and tryptase in the circulation of patients with food allergy and to determine whether the measurements of plasma histamine and tryptase concentrations after food challenges provided additional predictive markers for the diagnosis and evaluation of food allergy. Twenty-one open food challenges were performed on 13 patients with suspected food allergy. Plasma histamine and tryptase concentrations were measured during 4 hours after challenge. In the group of patients with immediate reactions after challenges, the mean plasma histamine concentration rose significantly at 120 and 240 minutes after the challenge, and the mean plasma tryptase concentration was increased significantly at 240 minutes after challenge. Plasma histamine and tryptase concentrations were measured during 24 hours after 8 open food challenges in 7 other patients with suspected food allergy. In each patient with a nonimmediate reaction, plasma histamine concentrations were increased at the onset of symptoms after challenge, but no plasma tryptase concentrations increased. The elevation of plasma histamine and tryptase in patients with immediate reactions following food challenge indicates mast cell activation. On the other hand, the elevation of plasma histamine without elevated plasma tryptase in the patients with nonimmediate reactions following food challenge may indicate basophil activation rather than mast cell activation. Plasma histamine and tryptase measurements after food challenge may be useful in the detection and evaluation of food allergy.

Beneficial effects of dietary intervention on serum lipid and apolipoprotein levels in obese children.

Effects of weight reduction on serum levels of lipids and apolipoproteins were measured in 13 obese children (seven girls, six boys). Mean weight loss of 8.4% of the initial body weight was achieved after 4 weeks of energy intake restriction and exercise. Serum total cholesterol (5.46 +/- 1.01 mmol/L) and triglyceride (2.08 +/- 0.52 mmol/L) levels were significantly high compared with control values before treatment and were significantly reduced to 4.32 +/- 0.75 and 1.31 +/- 0.42 mmol/L, respectively, after treatment. Serum high-density lipoprotein cholesterol level (1.03 +/- 0.23 mmol/L) was significantly low and unchanged after treatment (0.94 +/- 0.25 mmol/L). Serum apolipoprotein A-I level (0.039 +/- 0.009 mmol/L or 111 +/- 0.26 g/L) was normal before treatment and significantly reduced, to 0.032 +/- 0.007 mmol/L or 0.92 +/- 0.19 g/L, after weight reduction. Serum apolipoprotein B level (0.00019 +/- 0.00007 mmol/L or 1.07 +/- 0.21 g/L) was significantly high before treatment and decreased to the normal range after treatment (0.00014 +/- 0.0009 mmol/L or 0.76 +/- 0.24 g/L). The ratio of apolipoprotein B to apolipoprotein A-I (1.09 +/- 0.29) was significantly high on admission and decreased significantly to 0.64 +/- 0.12 after treatment. Serum apolipoprotein E level (0.0014 +/- 0.0006 mmol/L or 0.05 +/- 0.02 g/L) was normal and decreased to 0.0008 +/- 0.0002 mmol/L or 0.03 +/- 0.01 g/L after treatment. In conclusion, weight reduction achieved by energy intake restriction and exercise had beneficial effects on serum lipid and apolipoprotein concentrations for the prevention of future atherosclerosis.