Cytokines involved in graft-versus-host disease

Graft-versus-host disease (GVHD) is one of the major complications which should be resolved to improve the survival rates in allogeneic bone marrow transplantation (BMT). Recently, several cytokines have been identified, suggesting that they form a cytokine network and play an important role in immune system and hematopoiesis. Among several cytokines, it has been reported that tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) are mainly involved in GVHD. In the present report, we analyzed the role of cytokines in GVHD. When we measured serum cytokine levels, IL-6, interferon gamma (IFN gamma), and TNF alpha levels were increased prior to the onset of acute GVHD. For chronic GVHD, a similar pattern of cytokine increment was observed. Interestingly, these cytokines appeared to interact synergistically to induce clinical GVHD, suggesting that none of those cytokines does not function solely. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that increased IL-1 beta mRNA expression was also observed in acute GVHD in addition to increased IL-6 and TNF alpha mRNA expressions. Unexpectedly, no increased IL-2 levels were observed in both assays. In hyperacute GVHD, only IL-6 level was increased. However, in vivo administration of IL-6 into allogeneic bone marrow chimeras did not induce severe GVHD. Therefore, some other factors also appeared to be involved in inducing hyperacute GVHD. Furthermore, it is important to consider the role of inhibitory cytokines such as transforming growth factor beta (TGF beta) or IL-10.

[Clinical and serological studies in six cases of chlamydial pneumonia]

Clinical and serological studies of chlamydial pneumonia were done in six patients (three men and three women). The other three patients had no avian contact and showed almost the same clinical symptom. Acute infection with Chlamydia psittaci and Chlamydia pneumoniae were diagnosed in two patients and in one patient, respectively, by MFA. Because in some cases Chlamydia psittaci pneumonia and Chlamydia pneumoniae pneumonia are difficult to differentiate, it is necessary to use a test that allows different chlamydia species to be distinguished.

Cloning of the cDNA for a hematopoietic cell-specific protein related to CD20 and the beta subunit of the high-affinity IgE receptor: evidence for a family of proteins with four membrane-spanning regions

We report the cloning of the cDNA for a human gene whose mRNA is expressed specifically in hematopoietic cells. A long open reading frame in the 1.7-kb mRNA encodes a 214-aa protein of 25 kDa with four hydrophobic regions consistent with a protein that traverses the membrane four times. To reflect the structure and expression of this gene in diverse hematopoietic lineages of lymphoid and myeloid origin, we named the gene HTm4. The protein is about 20% homologous to two other "four-transmembrane" proteins; the B-cell-specific antigen CD20 and the beta subunit of the high-affinity receptor for IgE, Fc epsilon RI beta. The highest homologies among the three proteins are found in the transmembrane domains, but conserved residues are also recognized in the inter-transmembrane domains and in the N and C termini. Using fluorescence in situ hybridization, we localized HTm4 to human chromosome 11q12-13.1, where the CD20 and Fc epsilon RI beta genes are also located. Both the murine homologue for CD20, Ly-44, and the murine Fc epsilon RI beta gene map to the same region in murine chromosome 19. We propose that the HTm4, CD20, and Fc epsilon RI beta genes evolved from the same ancestral gene to form a family of four-transmembrane proteins. It is possible that other related members exist. Similar to CD20 and Fc epsilon RI beta, it is likely that HTm4 has a role in signal transduction and, like Fc epsilon RI beta, might be a subunit associated with receptor complexes.

Analysis of the mechanism for acetylcholine release at the synapse formed between rat sympathetic neurons in culture

Superior cervical ganglion neurons (SCGNs) were isolated from 7-day-old rat SCG and cultured in MEM containing horse serum, fetal calf serum, and nerve growth factor. In this culture condition, it is well known that the SCGNs form cholinergic synapse. In 3-4 weeks cultured neurons, immunofluorescent staining for synaptophysin, a small synaptic vesicle associated protein, showed the presence of synaptophysin as small dots on the surface of the soma. Postsynaptic potentials could be recorded in 50-80% of the neurons responding to evoked action potentials elicited in neighboring neurons. Because of its relatively large cell size and the short distance to the terminal, this synapse is a useful model for studying the mechanisms of acetylcholine (ACh) release by introducing substances such as antibodies or selective inhibitors into the presynaptic neuron by means of the whole-cell clamp technique. In this model synapse we tested the possible role of myosin in ACh release. The distribution of myosin was studied by the immunofluorescent staining technique. Myosin was recognized by the anti-myosin II IgG at the same synaptic terminals that showed the presence of synaptophysin with its antibody. The functional blockade of myosin by the antibody itself, and that of myosin light chain kinase (MLCK) by a pseudosubstrate inhibitor of MLCK, SM-1, or by a selective inhibitor of MLCK, wortmannin, induced depression of synaptic transmission in a dose-dependent manner. These indicate that phosphorylation of myosin by MLCK may be necessary for ACh release mechanisms.

[Dose intensity in M-VAC chemotherapy with rG-CSF for metastatic transitional urothelial cancer]

The effect of M-VAC (methotrexate, vinblastine, adriamycin and cisplatin) chemotherapy supported recombinant human granulocyte stimulating factor (rG-CSF) was studied in 18 patients with metastatic urothelal cancer. The mean age of the patients was 66 years. Of the patients 6 had lung metastasis and 12 had distant lymph node metastasis. In this study recombinant human granulocyte stimulating factor was administered therapeutically at 100 to 250 micrograms subcutaneously after the white blood cell count was less than 3,000/mm. Relative dose-intensity (RDI) was 0.88 +/- 0.11 and 0.72 +/- 0.19 for 11 patients with rG-CSF and 7 without rG-CSF, respectively. The relative dose regardless of the interval of the cycle of M-VAC chemotherapy (%Dose) was 0.95 +/- 0.06 and 0.86 +/- 0.09 for the patients with rG-CSF and those without rG-CSF, respectively. Of seven patients without rG-CSF 3 patients responded (response rate 42%, mean survival period 7.4 months). Of 11 patients treated with rG-CSF 3 patients responded (response rate 72.7%, mean survival period 20.0 months). Although rG-CSF increased the RDI of M-VAC chemotherapy, the correlation of response with RDI was not clearly demonstrated. The therapeutical administrations of rG-CSF fail to improve the mean white blood cell nadir and to prevent the decrease of the platelet and reticulocyte count.

Improved clearance of radiolabeled biotinylated monoclonal antibody following the infusion of avidin as a "chase" without decreased accumulation in the target tumor

The techniques of radioimmunoimaging and radioimmunotherapy suffer from prolonged high background radioactivity because intravenously injected antibodies remain in the circulation and in the organs far longer than necessary for effective binding to the target. To decrease background and increase radionuclide excretion without decreasing the dose of radioactivity delivered to the target tumor, we used radiolabeled biotinylated antibodies followed by a "chase" avidin injection.

METHODS

A mouse monoclonal antibody, OST7 (IgG1), which reacts with human osteosarcoma, was biotinylated and labeled with 125I, 131I or 99mTc. Radiolabeled biotinylated OST7 (10 micrograms) was administered intravenously into nude mice bearing human osteosarcomas and 30 micrograms of avidin was injected intravenously 6 or 24 hr later.

RESULTS

Following avidin injection in mice pretreated with radiolabeled biotinylated antibodies, radioactivity was promptly cleared from the blood and deposited in the liver and spleen, after which radioiodine was rapidly detached from the antibody and excreted in the urine. The tumor-to-blood ratios at 6 and 24 hr after the injection of 125I-labeled biotinylated OST7 increased compared with the values before the avidin chase without any loss of tumor radioactivity. Furthermore, the tumor-to-background radioactivity ratio was improved and better images were obtained more rapidly after the injection of radiolabeled biotinylated antibodies than with conventional immunoscintigraphy.

CONCLUSIONS

This method may find application in clinical radioimmunoimaging, especially using short half-life radionuclides such as 99mTc and 123I.

[Initial myocardial uptake and myocardial clearance of 123I-metaiodobenzylguanidine in patients with ischemic heart disease of left ventricular dysfunction and dilated cardiomyopathy]

We studied initial myocardial uptake and myocardial clearance of 123I-metaiodobenzylguanidine (MIBG) in patients with ischemic heart disease of left ventricular dysfunction and dilated cardiomyopathy. Eleven patients with ischemic heart disease of left ventricular dysfunction (IHD group), 6 patients with dilated cardiomyopathy (DCM group) and 7 control cases (control group) were studied. Heart to mediastinum activity ratio (H/M) of early and delayed image was significantly lower in the IHD and DCM groups than in the control group. Although initial myocardial uptake of MIBG showed no significant difference among three groups, myocardial clearance of MIBG was significantly higher in the IHD (35 +/- 11%) and DCM (48 +/- 13%) groups than that in the control group (19 +/- 10%). H/M of delayed image was related to the left ventricular size, initial MIBG uptake and MIBG myocardial clearance. Negative correlation was observed between MIBG myocardial clearance and left ventricular ejection fraction in all cases. In conclusion, initial myocardial uptake of MIBG were not decreased in patients with IHD and DCM. Enhanced myocardial clearance of MIBG was observed not only in patients with DCM but also in patients with IHD.

[Evaluation of myocardial viability and efficacy of reperfusion therapy by dual-SPECT using 99mTc-PYP and 201Tl in acute myocardial infarction]

Dual SPECT using 99mTc-PYP and 201Tl was performed in 70 patients with acute myocardial infarction, and the ratio of overlap zone between 201Tl and 99mTc-PYP uptake in the infarcted area was determined (the Y-ratio). The Y-ratio was significantly higher in the group with redistribution in the infarcted area on exercise thallium myocardial scintigraphy in the chronic stage of infarction, as well as in the group with normal left ventricular wall motion. Thus, the Y-ratio value was apparently useful in the evaluation of myocardial viability. Patients from 60% of the Y-ratio upward are suggested that myocardial viability had been survived. When the Y-ratio was determined in 30 patients who underwent early reperfusion therapy (ICT or direct-PTCA), no significant difference was found between the ICT group and the direct-PTCA group. However, the Y-ratio was significantly higher when reperfusion was performed within 6 hours than when it was performed after 6 hours, and a significant positive correlation (r = 0.63, p < 0.01), was found between reperfusion time from cardiac event within 9 hours and the value of (100--the Y-ratio).

CONCLUSION

The Y-ratio was grateful appeared to be useful for the quantitative evaluation of myocardial viability in the acute stage of myocardial infarction. In addition, it appears to be important to perform reperfusion as soon as possible to improve myocardial salvage.

[Phase II study of a continuous five-day intravenous infusion of cisplatin and etoposide with concurrent chest radiation therapy in limited stage small cell lung cancer]

The efficacy of continuous five-day intravenous infusion of cisplatin (CDDP) and etoposide with concurrent chest radiation therapy was evaluated in patients with limited stage small cell lung cancer. The first group of patients registered from February 1989 to September 1990 received three courses of chemotherapy (CDDP 20 mg/m2/day x 5 days, etoposide 40 mg/m2/day x 5 days) and concurrent chest radiation therapy on the third course with dose reduction of etoposide. The second group of patients registered after February 1991 received four courses of chemotherapy (CDDP 20 mg/m2/day x 5 days, etoposide 50 mg/m2/day x 5 days) and concurrent chest radiation therapy on the first and second courses with dose reduction of etoposide. The response rates were 91.7% and 93.3%, respectively. The median duration of survival was 32.0 months and 20.1 months, respectively. Major toxicity was leukocytopenia and 64% and 80% of patients encountered leukocytopenia of Grade 3 or 4. In conclusion, these regimens show remarkable efficacy with acceptable toxicity.

Structure of cell wall mannan of Candida kefyr IFO 0586

We conducted a structural analysis of the antigenic cell wall mannoprotein (mannan) isolated from Candida kefyr (formerly Candida pseudotropicalis) IFO 0586. The result of two-dimensional homonuclear Hartmann-Hahn analysis of this mannan indicates that the molecule is constructed from alpha-1,2- and alpha-1,6-linked mannopyranose residues. Upon alkali treatment (beta-elimination reaction), this mannan released two alpha-1,2-linked mannooligosaccharides, biose and triose. The structure of the alkali-stable mannan (outer chain) moiety was investigated by acetolysis. The structures of the resultant oligosaccharides, biose and triose, from the outer chain moiety were found to be the same as those of the alkali-released ones. Further, the treatment of the parent mannan with an Arthrobacter GJM-1 exo-alpha-mannosidase gave a linear mannan consisting solely of alpha-1,6-linked mannopyranose residues. These results indicate that the mannan forms the long backbone of the alpha-1,6 linkage, with a large number of short alpha-1,2-linked oligomannosyl side chains forming a comblike structure. Moreover, we investigated the serological properties of this mannan by performing an inhibition assay of a slide agglutination reaction with mannooligosaccharides and polyclonal factor sera (Candida Check; Iatron). The result indicates that the factor 1 serum preferentially recognizes the alpha-1,2-linked oligomannosyl side chains in this mannan. On the other hand, the fact that the mannan does not contain an antigenic determinant(s) corresponding to factor 8 suggests that the epitope(s) of this factor resides in other molecules on the cell surface of this strain.

Case report: uptake of pentavalent technetium-99m dimercaptosuccinic acid by pigmented villonodular synovitis: comparison with computed tomography, magnetic resonance imaging and gallium-67 scintigraphy

The scintigraphic findings of a patient with pigmented villonodular synovitis are described and compared with the computed tomography and magnetic resonance imaging data. Intense uptake of pentavalent technetium-99m dimercaptosuccinic acid without gallium-67 citrate uptake indicates that pigmented villonodular synovitis has the features of a hyperplastic or neoplastic lesion rather than an inflammatory lesion from the point of view of nuclear medicine.

Construction and expression of chimeric antibodies by a simple replacement of heavy and light chain V genes into a single cassette vector

A novel vector pMH-gpt, which is proved useful for cloning mouse immunoglobulin heavy and light chain V genes and for expressing mouse-human chimeric antibody, was constructed. The vector contains human genomic C gamma 1 and C kappa genes, cloning sites for immunoglobulin V region genes, murine Ig promoters, a human Ig heavy chain enhancer, and the selection marker gene Eco-gpt. Because VH and V kappa genes can be cloned into a single vector, a chimeric antibody gene is easily constructed by this simple insertion procedure. The usefulness of the vector was confirmed by construction of two mouse-human chimeric antibodies. Mouse monoclonal antibody (MAb) 196-14 recognizes the ovarian cancer-associated antigen (CA125), and MoAb 2-18 reacts with carcinoembryonic antigen (CEA). Mouse-human chimeric 196-14 and 2-18 antibodies were readily constructed and efficiently produced in a mouse myeloma cell line by utilizing the vector. Both chimeric antibodies retained binding activity to their respective antigens. In biodistribution and immunoscintigraphy studies, specificity of radiolabeled chimeric 196-14 antibody was identical to that of its murine counterpart and significant accumulation at the tumor site was observed. The pMH-gpt vector is useful for constructing and producing mouse-human chimeric antibodies.

Selective inhibition of exoplasmic membrane fusion in echinoderm gametes with jaspisin, a novel antihatching substance isolated from a marine sponge

A specific inhibitor of fertilization of the sea urchin Hemicentrotus pulcherrimus was isolated from the extract of the marine sponge, Jaspis species. Chemical and spectral data of the purified substance, which was designated jaspisin, showed that it is a novel substance with the structure of sodium (E)-5,6-dihydroxystyryl sulfate. Jaspisin at 15 micrograms/ml inhibited exoplasmic fusion of the plasma membrane of acrosome-reacted sperm with the plasma membrane of the egg; it did not affect either the acrosome reaction in sperm or the egg cortical reaction, both of which involve endoplasmic membrane fusion events. When a fertilized egg was cultured in jaspisin, the embryo developed through the mesenchymal blastula stage. However, it was unable to hatch from the fertilization envelope, and spiculogenesis, in which cell-cell fusion of primary mesenchyme cells is involved, was prevented. Jaspisin at 8.6 micrograms/ml inhibited half the activity of hatching enzyme, a kind of Zn(2+)-dependent metalloendoproteinases. Because Zn(2+)-activated metalloendoproteinases are suggested to be involved in both sperm-egg fusion and fusion of primary mesenchyme cells (Lennarz, W.J., and Strittmatter, W.J. (1991) Biochim. Biophys. Acta 1071, 149-158), one of the possible explanations of the jaspisin effects is that the sulfate inhibits these cellular events through blockage of Zn(2+)-activated metalloendoproteinases that are involved in membrane fusion processes.

Intraosseous hemangiomatosis: technetium-99m(V)dimercaptosuccinic acid and technetium-99m-hydroxymethylene diphosphonate imaging

We report a case of histologically proven intraosseous hemangiomatosis in which marked accumulation of pentavalent technetium-99m-dimercaptosuccinic acid (99mTc(V)DMSA) and technetium-99m-hydroxymethylene diphosphonate (99mTc-HMDP) was observed in the osteolytic hemangiomatous lesions.

The p15gag and p12gag regions are both necessary for the pathogenicity of the murine AIDS virus

The defective murine AIDS (MAIDS) virus has unique sequences in its p15gag and p12gag regions. To clarify whether these sequences are responsible for the development of MAIDS, we constructed recombinant viruses by replacing various regions of the gag gene of the nonpathogenic replication-competent LP-BM5 ecotropic virus with those of the MAIDS virus. Recombinants containing both unique sequences of the MAIDS virus were replication defective and induced MAIDS. However, a recombinant containing either the p15gag or p12gag region of the MAIDS virus was also replication defective but nonpathogenic in mice. A recombinant virus containing only the p30gag region of the MAIDS virus was replication competent and nonpathogenic. These results indicate that the p15gag and p12gag regions of the MAIDS virus do not function like those of replication-competent viruses and that both of the unique sequences in the p15gag and p12gag regions are required to develop MAIDS.

Modulation of platelet-derived growth factor-beta mRNA expression and cell growth in a human mesothelioma cell line by a hammerhead ribozyme

Malignant mesothelioma in humans is a rare disease, but it has recently received much public attention and concern because of its strong relationship to exposure to asbestos. We have found overexpression of the gene for platelet-derived growth factor (PDGF)-beta in several mesothelioma xenografts in nude mice. Because some mesothelioma cell lines such as VAMT-1 overexpress PDGF-beta and PDGF-beta receptors, it was considered that an autocrine loop involving PDGF-beta and its receptor may contribute to the malignant phenotype of these cells. To investigate this possibility we have developed a hammerhead ribozyme against PDGF-beta mRNA. This c-sis ribozyme was able to cleave an artificial PDGF-beta RNA substrate in a cell-free system. Transduction of this ribozyme, with the aid of a constitutive expression vector, in the VAMT-1 cell line led to a decrease in the PDGF-beta mRNA level. The ribozyme expressed in these cells was functional in cleaving the artificial RNA substrate in vitro. Ribonuclease protection assays using the ribozyme and whole PDGF-beta mRNA showed that this ribozyme was capable of cleaving the whole mRNA in vivo. Transfectant clones containing the wild-type ribozyme showed decreased cell growth, in parallel with the decreases in PDGF-beta expression. The disabled ribozyme was inactive in the cleavage reaction in vitro and in decreasing the cell growth rate in vivo. Our data indicate that in some mesothelioma cells the PDGF-beta autocrine loop may be functional and transduction of the PDGF-beta ribozyme leads to a significant reduction of cell growth. The c-sis ribozyme may be applicable in the treatment of patients with malignant mesothelioma.

Nerve growth factor receptor staining of suction biopsies in the diagnosis of Hirschsprung's disease

The authors studied rectal suction biopsy material in 60 consecutively treated patients suspected of having Hirschsprung's disease (HD) (age range, 3 days to 12 years). According to acetylcholinesterase (AChE) staining, 10 patients had HD, three had neuronal intestinal dysplasia (NID), and 47 were normal. The diagnoses were confirmed by H&E staining of biopsy material and by examination of surgically resected material in the HD and NID cases. The 60 cases were stained with a monoclonal antibody to the nerve growth factor receptor (NGFR) using immunohistochemistry on fresh frozen biopsy tissue. In the 47 normal biopsy specimens, there was a large number of immunoreactive fibers in the lamina propria, and staining of the muscularis mucosae and submucous ganglia. In contrast, there were no immunoreactive fibers in the lamina propria in patients with HD and NID. A striking finding was the strong expression of immunoreactivity on the perineurium of submucosal hypertrophic nerve trunks in cases of HD. The results indicate that NGFR immunoreactivity is similar in specificity and sensitivity to AChE in the diagnosis of HD. Because the technique uses an immunocytochemical rather than a histochemical technique and the results were easier to interpret, NGFR staining may be an important additional technique to diagnose HD.

Intrinsic or acquired drug resistance and metastasis: are they linked phenotypes?

Evidence is reviewed which suggests a linkage may exist between certain forms of de novo or acquired drug resistance and metastasis. This includes the finding that expression of certain dominantly acting mutant oncogenes or tumor suppressor genes, i.e., genes which normally act to "drive" tumor progression and metastasis, can also affect the expression of drug resistance. Moreover, this can be accompanied by altered expression of certain cellular genes thought to be involved in expression of drug resistance. A direct linkage between acquired drug resistance and metastasis would suggest that tumor sublines selected for drug resistance should manifest more aggressive malignant properties than their drug-sensitive counterparts. While this does not appear to be true for drug resistant sublines selected in vitro, indeed such cell lines frequently manifest diminished in vivo tumorigenic and/or metastatic competence, there is some evidence to support such a correlation exists for tumor cell lines that are selected in vivo for drug resistance. Attention is also drawn to the fact that new linkages between metastasis and drug resistance may be uncovered by analyzing the ability of tumor subpopulations to acquire drug resistance after one or several previous exposures to chemotherapeutic drugs, as opposed to examining intrinsic drug resistance only. Furthermore, ability to detect induced or acquired drug resistance in vitro may be strongly influenced by the types of assay used to detect and monitor drug resistance. In particular, three-dimensional cell culture systems may reveal acquired or induced "multicellular" drug resistance in situations where conventional two-dimensional culture systems do not. Use of three-dimensional culture systems may therefore reveal as yet undiscovered associations between the phenotypes of metastasis and drug resistance.

[Mechanism of hypoxemia after methacholine challenge]

Hypoxemia after the treatment of asthmatic attack continues for a while, and can even become worse after the treatment. This hypoxemia has been attributed to inhomogeneity of ventilation-to-perfusion ratios in the lungs of asthmatic patients. We studied post-hyperventilation hypoxemia in subjects with hypoxemia after a methacholine challenge test. Nineteen subjects who were hyperresponsive and hypoxemic after a methacholine challenge were studied. The methacholine challenge with incremental doses was stopped when the respiratory resistance doubled. Thereafter, oxygen and carbon dioxide concentrations in the expired air, mouth flow (VE), and oxygen saturation (using a pulse oximeter, SpO2) were monitored continuously. End-tidal PCO2 (PETCO2) as well as respiratory exchange ratio (R) were thus obtained. In 14 subjects, VE significantly increased from 8.6 +/- 1.2 (mean +/- SD) to 13.4 +/- 2.6 l/min and then decreased gradually, while PETCO2 significantly decreased from 38.5 +/- 2.3 to 29.1 +/- 4.4 Torr and then increased gradually, SpO2 decreased from 97 +/- 1.3 to 89 +/- 2.4% concomitant with a significant decrease in R from 0.86 +/- 0.04 to 0.67 +/- 0.05. In contrast, in 5 subjects VE significantly increased from 7.5 +/- 2.8 to 12.4 +/- 1.6 l/min and then remained unchanged, while PETCO2 significantly decreased from 37.9 +/- 1.3 to 31.3 +/- 3.9 Torr and then remained unchanged, SpO2 decreased from 98 +/- 1.1 to 92 +/- 1.9% with no change in R (from 0.84 +/- 0.06 to 0.87 +/- 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma endothelin levels in congenital diaphragmatic hernia

Persistent pulmonary hypertension (PPH) together with pulmonary hypoplasia accounts for high mortality among patients with congenital diaphragmatic hernia (CDH). Endothelin (ET) is a recently described endothelium-derived vasoconstrictor peptide with a potent and sustained effect. The authors examined plasma ET levels in eight patients with CDH who had respiratory distress at birth and in 15 age-matched controls. The plasma ET levels were measured using a highly sensitive and specific enzyme immunometeric assay (EIA) preoperatively, intraoperatively, and 24 and 48 hours postoperatively. The mean preoperative plasma ET level (53.9 +/- 21.1 pg/mL) of the patients was significantly (P < .01) higher than that of controls (5.9 +/- 4.5 pg/mL). Two patients who died before operation had plasma ET levels of 60 pg/mL and 82 pg/mL, respectively. Three patients who had PPH postoperatively continued to have high ET levels, and at 48 hours, the mean plasma ET level in these patients was 33 pg/mL. In contrast, in the three patients who survived after repair of CDH, the mean plasma ET level at 48 hours was 1.3 pg/mL. The authors further examined the lungs of two patients who died before operation for the expression of ET, using immunocytochemistry. Pulmonary endothelial cells had strong ET staining compared with control tissues. These findings suggest that ET may be a pathophysiological mediator of pulmonary hypertension in patients with CDH.