Induction of heat shock response: effect on the rat liver with carbon tetrachloride-induced fibrosis from ischemia-reperfusion injury

The role of heat shock pretreatment in the induction of tolerance for ischemia-reperfusion injury was investigated in rat livers with fibrosis produced by carbon tetrachloride (CCI4) injected subcutaneously. The control group (group C, n = 56) received no pretreatment except anesthesia, and the heat shock group (group HS, n = 56) were exposed to heat shock (42 degrees C) for 15 minutes. After a 48-hour recovery all rats were subjected to 30 minutes of warm ischemia. Western blotting analysis was employed for heat shock protein (HSP) 72 detection. The adenine nucleotide levels in liver tissue and the liver enzyme levels in serum were measured before and after ischemic intervention (seven animals were used at each of six time point measurements in both groups). HSP72 was induced in group HS at greater intensity than in group C. The survival rate on postoperative day 7 in group C (3/14) was significantly poorer than that in group HS (14/14) (p < 0.01). The higher survival rate in group HS was accompanied by more rapid recovery of the adenosine triphosphate level and lower serum levels of liver enzymes after reperfusion (p < 0.01 vs. group C). Heat shock preconditioning induces HSP72 in the rat liver with fibrosis and provides significantly increased tolerance of warm-ischemia reperfusion injury.

Comparison of cyclooxygenase-1 and -2 inhibitory activities of various nonsteroidal anti-inflammatory drugs using human platelets and synovial cells

Recent studies have shown that cyclooxygenase exists in two isozyme forms. Since differences in the pharmacological profiles of nonsteroidal anti-inflammatory drugs (NSAIDs) might be accounted for by varying degrees of selectivity for these isozymes, cyclooxygenase-1 and -2, the relative potency of various NSAIDs in inhibiting their activities was examined in intact human cells. We used human platelets cyclooxygenase-1 and interleukin-1beta-stimulated human synovial cell cyclooxygenase-2 for measuring cyclooxygenase selectivity. The presence of the enzymes was confirmed by immunoblotting and immunoprecipitation analysis, and by the reverse transcriptase-polymerase chain reaction. Mean IC50 values (microM) for human platelet cyclooxygenase-1 and interleukin-1beta-stimulated human synovial cell cyclooxygenase-2 and cyclooxygenase-1/-2 IC50 ratio of various NSAIDs were as follows: aspirin, 3.2, 26, 0.12; diclofenac, 0.037, 0.00097, 38; etodolac, 122, 0.68, 179; ibuprofen, 3.0, 3.5, 0.86; indomethacin, 0.013, 0.044, 0.30; loxoprofen (active metabolite), 0.38, 0.12, 3.2; NS-398, 12, 0.0095, 1263; oxaprozin, 2.2, 36, 0.061; zaltoprofen, 1.3, 0.34, 3.8; respectively. Our bioassay system employing intact human cells to assess the cyclooxygenase selectivity of NSAIDs may provide clinically useful information.

Upregulation of CD44 in the inflamed mouse air pouch injected with synthetic lipid A

OBJECTIVE

To investigate aspects of the inflammatory process of the mouse subcutaneous air pouch -- a facsimile synovial cavity -- induced by injection of lipid A, and to determine the expression and upregulation of CD44 in the lining cell layer of the inflamed air pouch.

METHODS

Histological changes of inner walls in the mouse air pouch were evaluated 1, 3, and 7 days after injection of lipid A.

RESULTS

Polymorphonuclear cell infiltration in the lining layer reached the maximum one day after injection of 10 microg of lipid A (10/10 mice in Grade 3; p < 0.01), while mononuclear cell infiltration and lining cell hyperplasia reached the maximum 3 days after injection (5/10 mice in Grade 2; 5/10 in Grade 3; p < 0.05; 39+/-11 layers, p < 0.05, respectively). The number of cell depth of CD44 positive lining layers and interleukin 1alpha (IL-1alpha) positive lining layers reached the maximum 3 days after injection (39+/-7 layers, p < 0.01; 35+/-12 layers, p < 0.05, respectively).

CONCLUSION

These findings suggest that CD44 may have some connection with the proinflammatory cytokine IL-1alpha and induce inflammatory responses in the air pouch injected with lipid A.

Isolation and differential secretion of metalloproteinase by superficial chondrocytes in articular cartilage

Chondrocytes from superficial layers of articular cartilage have distinct phenotypic properties which are different from those of cells obtained from the deeper areas. We describe a method that isolates highly purified articular cartilage chondrocytes from the superficial layers. When the superficial cells are stimulated in vitro with a source of cytokines, they secrete greater amounts of metalloproteinase compared to chondrocytes obtained from a deeper area.

Adverse effects of reverse triiodothyronine on cellular metabolism as assessed by 1H and 31P NMR spectroscopy

Effects of 3,3',5'-triiodothyronine (rT3) in connection with 3,3',5-triiodothyronine (T3) on 3T3 cells were studied in vitro by means of 1H and 31P NMR spectroscopy. In the cells incubated with 5 nM T3 for 3 h at pH 7.4, the ATP/ADP ratio was elevated from 6.9 to 8.4, whereas it was reduced to 6.1 in cells incubated with rT3. When the cells were incubated at pH 6.7, the ATP/ADP ratio was reduced to 6.6 and 5.2 at 1 and 2 h, respectively. In the presence of 5 nM of T3, however, the ratio was maintained above the control level. A 1-h preincubation with rT3 dramatically augmented the reductions caused by elevated acidity. These reductions were completely reversed when the cells were incubated with T3.

Case report of rec(7)dup(7q)inv(7)(p22q22) and a review of the recombinants resulting from parental pericentric inversions on any chromosomes

We report a rare case of duplication for 7q22 --> 7qter and deletion for 7p22 --> 7pter, resulting from a meiotic recombination of a paternal pericentric inversion, inv(7)(p22q22). The newborn boy had the 7q trisomy syndrome. In addition, the diagnosis of chondrodysplasia punctata was made from lumbar and hand X-ray films taken soon after birth. Only two cases of rec(7)dup(7q), both in a single family, have been reported previously. We review 133 offspring with recombinations resulting from pericentric inversions on any chromosomes reported between 1981 and 1995. Of the 133 cases, 110 had a long-arm duplication and short-arm deletion, while only 23 had a short-arm duplication and long-arm deletion. In 85 of the 133 cases, the mother was an inversion carrier (five carriers had two affected offspring), and in 46, the carrier was a father (one carrier had three affected offspring). Kaiser [Hum Genet 1984;68:1-47] reviewed 63 offspring with recombinations derived from a parental pericentric inversion reported between 1972 and 1981. In both surveys, recombinations resulting from pericentric inversions of chromosomes 1, 12, 19, and Y were not found.

[Relationship between the presence of side-holes in bone marrow aspiration needle and the number of harvested bone marrow mononuclear cells]

The aim of this study was to evaluate the yield of nucleated cells in bone marrow harvested by means of Downs' Islam aspiration needles with or without side-holes. Twenty marrow donors for HLA identical sibling transplants were studied. Bone marrow nucleated cells were harvested 50 ml in the right iliac bone with a Downs' Islam aspiration needle with or without side-holes and 50 ml in the left with another kind of needle by means of 5 ml aspirations in each donor. There were no significant difference between the number of nucleated cells by means of Downs' Islam aspiration needles with and without side-holes by cross-over analysis. All nucleated cell counts were 33.06 +/- 12.93 x 10(3)/microliter (mean +/- standard deviation) by means of the needle with side-holes and 32.90 +/- 15.25 x 10(3)/microliter by means of the needle without side-holes. The Downs' Islam aspiration needle without side-holes seems to be better in bone marrow harvest from normal volunteers than that with side-holes, because the former may be stronger than the latter.

[The care principles of home care based on the cognition of care providers]

The purpose of this study was to clarify the care principles that are most highly valued by various care providers, including public health nurses, home visiting nurses, home helpers, and case-workers, by factor-identification-study (KJ method), and to consider measures for sharing care principles among these sectors. It was found that care principles are composed of three factors: "User-oriented care", "Good mutual relationship", and "Self-improvement". Also there are differences in cognition of these according to occupation, workplace, experience, and so on. We should develop strategies for improving the quality of user-oriented care, as we understand the differences in cognition of care principles, and as we share the experience gained in each working aria.

[Relationship between iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid washout ratio and oxygen consumption in normal and ischemic myocardium]

The relationship between oxygen consumption and iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid (123I-BMIPP) washout at rest and after exercise was investigated in normal and ischemic myocardium. Sixteen healthy volunteers and 14 patients with ischemic heart disease were examined. After injection of 111MBq of 123I-BMIPP, serial single photon emission computed tomography imaging was performed to evaluate washout ratio after 30 min and 1 hour of rest and after exercise. In the volunteers, the mean washout ratio was 3.3 +/- 3.5% after 1 hour of rest and increased during exercise. The exercise washout ratio showed a better correlation with net pressure rate product (net PRP: cumulative values of PRP during exercise) than with the peak PRP. The exercise washout ratio showed a strong correlation with the net PRP in the range from 180 to 300 x 10(3) mmHg. beat/min and a plateau of 10-15%. In the nine ischemic patients with net PRP > or = 300 x 10(3) mmHg.beat/min, the exercise washout ratio values were significantly elevated in normal segments relative to ischemic segments (10.1 +/- 1.9% vs 4.7 +/- 2.9%, p < 0.001). In the five ischemic patients with net PRP < 300 x 10(3) mmHg.beat/min, washout ratio at rest and after exercise did not differ significantly between normal and ischemic segments. 123I-BMIPP washout ratio increased with increased oxygen consumption during exercise in normal myocardium but not in ischemic myocardium. The patient must exercise before fatty acid metabolism can be compared between normal and ischemic myocardium.

Risk factors for hepatic veno-occlusive disease after bone marrow transplantation: retrospective analysis of 137 cases at a single institution

One hundred and thirty-seven consecutive patients who received bone marrow or peripheral blood stem cell transplantation were studied retrospectively to identify the risk factors for hepatic veno-occlusive disease (VOD). Of the 137 recipients, twenty (14.6%) patients were diagnosed with VOD using the McDonald's criteria. In these 20 patients with VOD, we analyzed various clinical parameters, including age, sex, HLA status, conditioning regimen, irradiation, immunosuppressive agents, mode of transplantation, history of hepatic dysfunction, pre-transplant hepatic and renal function, infectious episodes, antibiotics use, and serum viral titers. A history of hepatic dysfunction and low levels of pseudocholinesterase before transplantation were found to be statistically significant (P = 0.04 and 0.04). Low levels of pseudocholinesterase were significant by multivariate analysis using the logistic regression model (P = 0.02). These results suggest that pseudocholinesterase levels before transplant are important markers of VOD in patients receiving BMT.

Comparison of cytomegalovirus (CMV) antigenemia and CMV in bronchoalveolar lavage fluid for diagnosis of CMV pulmonary infection after bone marrow transplantation

A comparative cytomegalovirus (CMV) diagnostic study was carried out on 30 bone marrow transplant patients. Forty-three bronchoalveolar lavage fluid (BALF) samples from these patients were examined for CMV by viral culture, polymerase chain reaction (PCR), shell vial and cytology. In parallel, peripheral blood samples were subjected to CMV antigenemia assay. CMV was detected in 12 (27.9%) of the 43 BALF samples (10 samples in viral culture, 10 samples in PCR, eight samples in shell vial and three samples in cytology). The CMV antigenemia assay yielded a positive result for six samples. The rates of agreement between results of the CMV antigenemia assay and results of each of the BALF tests were as follows: 81.4% with viral culture, 76.7% with PCR, 86.0% with shell vial, and 88.4% with cytology. Although the sensitivity of the CMV antigenemia assay was inferior to the sensitive tests of BALF samples, statistically significant correlations were demonstrated between the CMV antigenemia assay, viral culture, shell vial and cytology. Although the CMV antigenemia assay was shown to be useful for detection of CMV, it may be necessary to confirm not only the sensitivity but also the specificity of this method for prevention of CMV disease after BMT.

Aceclofenac blocks prostaglandin E2 production following its intracellular conversion into cyclooxygenase inhibitors

Aceclofenac, 2-[(2,6-dichlorophenyl) amino] phenylacetoxyacetic acid, is a novel non-steroidal anti-inflammatory drug. We investigated the effects of aceclofenac on prostaglandin E2 production by several kinds of human cells. Aceclofenac inhibited interleukin-1beta-induced prostaglandin E2 production by human rheumatoid synovial cells, but had no inhibitory effect on cyclooxygenase-1 or cyclooxygenase-2 activities by itself. We also observed that part of the aceclofenac was converted into diclofenac, the cyclooxygenase-1 and cyclooxygenase-2 inhibitor, when aceclofenac was incubated with human rheumatoid synovial cells. Aceclofenac was also converted into diclofenac and 4'-hydroxy diclofenac by human polymorphonuclear leukocytes and monocytes. 4'-Hydroxy diclofenac suppressed prostaglandin E2 production specifically by blocking cyclooxygenase-2 activity. These findings suggested that aceclofenac can be metabolized to cyclooxygenase inhibitors (diclofenac and/or 4'-hydroxy diclofenac) by these inflammatory cells. Although detailed examinations in non-inflammatory cells remain to be studied, we concluded that aceclofenac is shown to be a new type of non-steroidal anti-inflammatory drug which is intracellulary converted into active metabolites that inhibit the prostaglandin E2 production.

Targeted disruption of Cbfa1 results in a complete lack of bone formation owing to maturational arrest of osteoblasts

A transcription factor, Cbfa1, which belongs to the runt-domain gene family, is expressed restrictively in fetal development. To elucidate the function of Cbfa1, we generated mice with a mutated Cbfa1 locus. Mice with a homozygous mutation in Cbfa1 died just after birth without breathing. Examination of their skeletal systems showed a complete lack of ossification. Although immature osteoblasts, which expressed alkaline phophatase weakly but not Osteopontin and Osteocalcin, and a few immature osteoclasts appeared at the perichondrial region, neither vascular nor mesenchymal cell invasion was observed in the cartilage. Therefore, our data suggest that both intramembranous and endochondral ossification were completely blocked, owing to the maturational arrest of osteoblasts in the mutant mice, and demonstrate that Cbfa1 plays an essential role in osteogenesis.

[The mutation and the selection of inactivating enzymes against antibiotic resistances]

The genes coding for inducible beta-lactamase production from S. aureus pI258 showed constitutive expression in E. faecalis. These findings suggest that constitutive beta-lactamase production in E. faecalis is due to not only to the absence of functional regulatory genes but to some factors as well. However, hypothetical model for control of the expression of inducible ampC genes in Grm-negative bacteria is slightly different to that of S. aureus and E. faecalis. The muropeptide GlcNac-anhMurNac-tripeptide, tetrapeptide and pentapeptide are transport into the cytoplasm through AmpG. Intracellular accumulation of GlcNac-anhMurNac-tripeptide as the results of the presence of the beta-lactam antibiotics or of anhMurNac-tripeptide as the results of inactivation of ampD triggers production of E. cloacae AmpC beta-lactamase. The muropeptides presumably bind to the ampR, the transcriptional regulator, and convert it into an activator for ampC expression.

Accumulation of multiple T-cell clonotypes in the liver of primary biliary cirrhosis

The histological hallmark of primary biliary cirrhosis (PBC) is the destruction of the interlobular and septal bile ducts accompanied by a dense accumulation of lymphocytes; this constellation of features is termed chronic nonsuppurative destructive cholangitis. To analyze the T cells responsible for bile duct destruction, the T-cell receptor (TCR) Vbeta repertoire was studied in liver biopsy specimens, and also in peripheral blood lymphocytes (PBL) obtained from seven patients with PBC in the early stage (Scheuer's stage I or II). The complementary DNA (cDNA) of each TCR Vbeta1-20 chain was amplified by reverse-transcription polymerase chain reaction (RT-PCR), and the PCR products were examined by single-strand conformation polymorphism (SSCP) analysis. On the RT-PCR/SSCP analysis, a leukemic cell line, HPB-ALL, showed bands in TCR Vbeta 5.2 and Vbeta 6, indicating clonal expansion with distinct TCR. In the PBL from healthy subjects, the PCR products were amplified from many TCR Vbeta and were shown as smears on SSCP, suggesting that PBL consist of diverse T-cell clones. In PBC, many TCR Vbeta products were amplified by RT-PCR in both liver tissues and PBL, and no biased expression of a particular Vbeta was observed. SSCP analysis revealed multiple bands in most Vbeta chains, suggesting the presence of selected but multiple T-cell clones. Both the number and types of Vbeta showing clonal expansion were heterogeneous in the PBC patients. A comparative RT-PCR SSCP analysis of each TCR Vbeta between tissue lymphocytes and PBL revealed the presence of some identical T-cell clones in both the PBC liver and the PBL. These results suggest that T cells infiltrating the liver in PBC consist of multiple clonotypes and that T-cell clones accumulated in the liver are also present in PBL.

Detection of genes regulating beta-lactamase production in Enterococcus faecalis and Staphylococcus aureus

Four beta-lactamase-producing clinical isolates (WH245, WH257, CH570, and DEL) of Enterococcus faecalis were examined for the presence of the staphylococcal beta-lactamase regulatory genes (blaR1 and blaI) by PCR using six primer pairs. All isolates produced small amounts of beta-lactamase constitutively. In WH245, CH570, and DEL, the corresponding regions of the regulatory genes have lost sequences of various lengths. However, the regulatory genes in WH257 appeared to be the same as those in staphylococcal plasmid pI258. The beta-lactamase genes could be transferred to enterococcal and staphylococcal recipients from WH257 and DEL by conjugation or transformation with selection for gentamicin resistance. After transformation, the expression of beta-lactamase from DEL was still constitutive, whereas the gene from WH257 showed inducible expression in Staphylococcus aureus. The gene coding for inducible beta-lactamase production from pI258 showed constitutive expression in E. faecalis. These findings suggest that constitutive beta-lactamase production in E. faecalis is due not only to the absence of functional regulatory genes but to some other factor(s) as well.

Detection of tet(K) and tet(M) in Staphylococcus aureus of Asian countries by the polymerase chain reaction

This study describes the use of the polymerase chain reaction (PCR) to detect the tet(K) and tet(M) tetracycline resistance genes in Staphylococcus aureus. Primers based on the DNA sequence of the tet(K) and tet(M) genes from S. aureus were used as primers in the PCR assay to detect the presence of genes for resistance to tetracycline and minocycline. Two-hundred and fifteen isolates of S. aureus from Asian countries as Japan, Indonesia, China, Korea and Thailand were examined, and the results confirm that tet(K) specifies resistance to tetracycline but not to minocycline and tet(M) specifies resistance to both tetracycline and minocycline. We observed two different types of clinical isolates of S. aureus strains resistant to minocycline and tetracycline: the first carried only the tet(M) gene, while the second carried both the tet(M) and the tet(K) genes. Almost all of the clinical isolates of S. aureus resistant to minocycline and tetracycline from Indonesia, China and Thailand carried both tet(M) and tet(K) genes, while most of clinical isolates of S. aureuss from Japan and Korea carried only tet(M) gene.

Isolation of methicillin-resistant coagulase-negative staphylococci from chickens

Methicillin-resistant coagulase-negative staphylococci were isolated from the nares and skin of 1- to 8-week-old healthy chickens in three flocks from a farm. Isolation of methicillin-resistant coagulase-negative staphylococci was positive for 72 (25.7%) of the 280 chickens tested, with the frequency varying from 2.2 to 100% according to flock. A total of 45 appropriate isolates were selected and subjected to identification. Of the 45 methicillin-resistant coagulase-negative staphylococcal isolates selected, 37 were identified as Staphylococcus sciuri, 5 were identified as Staphylococcus epidermidis, and 3 were identified as Staphylococcus saprophyticus. The distribution of the species was different among the flocks. Comparative analysis of the SmaI-digested chromosomal DNA by pulsed-field gel electrophoresis revealed that the isolates could have originated from a single clone of each of S. sciuri and S. saprophyticus and three clones of S. epidermidis. By two methods based on the PCR technique, the mecA gene was detected in all five representative isolates of each methicillin-resistant coagulase-negative staphylococcal clone. The nucleotide sequence of a PCR fragment obtained from an isolate of S. sciuri was completely identical to the corresponding region of mecA genes reported in human methicillin-resistant Staphylococcus aureus isolates and Staphylococcus epidermidis isolates. The representative methicillin-resistant coagulase-negative staphylococcal isolates were resistant to many beta-lactam antibiotics, and some isolates were also resistant to macrolide and aminoglycoside antibiotics. This is the first evidence of the existence of methicillin-resistant coagulase-negative staphylococci from animals possessing the mecA gene.

[A case study of immunohistochemical findings of rheumatic pseudocystic lesions in the femoral lateral condyle and tibial plateau--the comparison with synovial lesions]

Rheumatoid pseudocysts of which pathogenesis are not well known, are commonly observed in the major joints of the body, especially knees in rheumatoid patients. This report investigated the pseudocysts in the knee of a rheumatoid patient radiologically and immunohistochemically. A sixty-three-year-old woman with rheumatoid arthritis who had pseudocysts in the femoral lateral condyle and tibial plateau was hospitalized to have the lesions surgically removed. The MRI findings showed a connection between the pseudocysts and the joint cavity. A window of 1 x 1 cm2 was made at the tibial anterior cortex and the contents of the pseudocyst were resected and hydroxyapatite granules were inserted into the lesion after the removal of the pseudocyst tissue. In the histological findings, the specimen from the tibial pseudocyst revealed fibrous connective tissue with a few inflammatory cells, while the synovial specimen revealed the fibrous tissue with intense inflammatory cells infiltration forming lymphoid follicules. In immunohistochemical findings, both specimens showed positive with anti-HLA class I, anti-HLA DR, anti-CD44 and anti-HSP70 antibodies. The pathological findings of the pseudocystic lesion were similar to those of synovia, and it was considered that the synovia had invaded into the bone and formed the pseudocystic lesion. The MRI findings also support this hypothesis. The pseudocystic lesion was surrounded by bone and it was isolated from cytokain-rich joint effusion. This isolation from rheumatic joint effusion may explain the weaker inflammation of the pseudocystic lesion than that of synovia.

Direct fermentative production of acyltylosins by genetically-engineered strains of Streptomyces fradiae

A tylosin-producer, Streptomyces fradiae, was transformed with plasmids carrying genes from Streptomyces thermotolerans that are involved in acyl modification of macrolide antibiotics. A transformant with pMAB3, in which macrolide 4"-O-acyltransferase gene (acyB1) and its regulatory gene (acyB2) are subcloned, produced several types of 4"-O-acyltylosins. A transformant with pAB11 delta EH containing macrolide 3-O-acyltransferase gene (acyA) in addition to the above two genes produced 3-O-acetyltylosin and 3-O-acetyl-4"-O-acyltylosins. Among the products of the latter transformant, 3-O-acetyl-4"-O-isovaleryltylosin (AIV) was detected as a minor component. When L-leucine, a precursor of isovaleryl-CoA, was added to the medium at the late stage of the fermentation, AIV content among the total macrolides increased ten-fold and AIV became a main product. This fact suggests that a high level of endogenous isovaleryl-CoA may be essential for the selective production of AIV by S. fradiae carrying pAB11 delta EH.

Pain reduction after anteromedial displacement of the tibial tuberosity: 5-year follow-up in 21 knees with patellofomoral arthrosis

We performed anteromedial displacement of the tibial tuberosity in 21 knees of 16 patients having patellofemoral arthrosis with lateral subluxation. The mean age of the patients was 53 (47-65) years and they were followed for 5(2-13) years. Preoperatively, all knees were painful on descending or ascending stairs; pain was relieved after operation in 20. Retropatellar crepitations disappeared in 2 of 20 knees, but retropatellar pain when squeezing the patella against the femur disappeared in 16 of 17 knees. Patellar subluxation diminished in all knees.

[Chronic myelocytic leukemia associated with cytomegalovirus induced sialoadenitis after unrelated allogeneic bone marrow transplantation]

A 26-year-old male with chronic myelocytic leukemia was admitted for unrelated allogeneic bone marrow transplantation (BMT). After BMT, he developed swelling of biateral submandibular glands accompanied with pneumonitis possibly due to cytomegalovirus (CMV). Biopsy from the left submandibular gland showed giant cells with nuclear inclusion bodies that were positive for anti-CMV-IE monoclonal antibody, there fore cytomegalic sialoadenitis was diagnosed. The administration of ganciclovir resulted in resolution of the pnumonitis and submandibular gland swelling. Although cytomegalic sialoadenitis is not a life-threating complication in BMT patients, it should be noted that biopsy is very useful for the diagnosis of systemic cytomegalovirus infection.

New evidence for the involvement of oxygen radicals in triggering neonatal chronic lung disease

We measured the plasma concentration of allantoin, an oxidation product of uric acid and an "in vivo" marker of free radical generation, within 24-48 h after birth in 10 premature infants who subsequently developed chronic lung disease (CLD) and 9 infants without CLD (non-CLD). The plasma allantoin level (mean +/- SD, 25.9 +/- 9.8 microM for CLD versus 11.0 +/- 5.7 microM for non-CLD, p < 0.01) and the allantoin/urate ratio (5.8 +/- 2.0% for CLD infants versus 2.4 +/- 0.9% for non-CLD infants, p < 0.01) were significantly higher in the CLD group than those in the non-CLD group. These observations suggest the possible involvement of oxygen radicals in triggering CLD. In addition, the plasma allantoin concentration and the allantoin/urate ratio may be useful early predictors of the development of CLD.