Substrate specificity of human monoamine (M)-form phenol sulfotransferase: preparation and analysis of Dopa 3-O-sulfate and Dopa 4-O-sulfate

Upon two-dimensional thin-layer separation, the sulfated L-3, 4-dihydroxyphenylalanine (L-DopaS) generated enzymatically was found to co-migrate with only one of the two ninhydrin-stained spots corresponding to the two sulfated forms (3-O-sulfate and 4-O-sulfate) of synthetic L-DopaS. To clarify precisely the identity of the enzymatically generated L-DopaS, the two sulfated forms of synthetic L-DopaS were separated and purified using high performance liquid chromatography. Purified L-Dopa 3-O-sulfate and L-Dopa 4-O-sulfate were identified by 1H-nuclear magnetic resonance (NMR) spectrometry and used as standards in the analysis of the L-DopaS generated during metabolic labeling of HepG2 human hepatoma cells or enzymatic assay using recombinant human monoamine (M)-form phenol sulfotransferase. The results obtained demonstrated unequivocally the generation of L-Dopa 3-O-sulfate, indicating the specificity of the M-form phenol sulfotransferase being for the meta-hydroxyl group of L-Dopa.

Molecular cloning, expression, and characterization of a novel mouse liver SULT1B1 sulfotransferase

A mouse liver homogenate was shown to contain enzymatic activities catalyzing the sulfation of 3,4-dihydroxyphenylalanine (Dopa) and tyrosine isomers with a pH optimum of 8.25. Western blot analysis revealed a 34 kDa protein exhibiting immunologic cross-reactivity to antiserum against rat liver SULT1B1 sulfotransferase. By employing the reverse transcriptase-polymerase chain reaction (RT-PCR) technique, a 910-base pair product encoding the putative mouse liver SULT1B1 sulfotransferase was obtained. Using this PCR product as a probe, a cDNA containing the entire open reading frame of the mouse liver SULT1B1 sulfotransferase was cloned from a mouse liver Lambda ZAP cDNA library. The nucleotide sequence indicated it is a new enzyme. The deduced amino acid sequence exhibited 87.6, 72.3, 55.9, 54.2, 52.8, 51.1, and 49.4% identity to the amino acid sequences of the rat liver SULT1B1 sulfotransferase, human thyroid hormone sulfotransferase, mouse phenol sulfotransferase, rat liver phenol sulfotransferase, rat liver hydroxyarylamine sulfotransferase, mouse estrogen sulfotransferase, and rat estrogen sulfotransferase. Upon transfection of COS-7 cells with an expression vector (pcDNA3) harboring the cDNA encoding this new enzyme, a 34 kDa protein exhibiting immunologic cross-reactivity to antiserum against the rat liver SULT1B1 sulfotransferase was expressed. The recombinant sulfotransferase exhibited enzymatic activities toward Dopa and tyrosine isomers, as well as dopamine and 3,3',5-triiodo-L-thyronine. Northern blot analyses indicated the SULT1B1 sulfotransferase was predominantly expressed in liver, but not in the other ten mouse organs examined. Furthermore, the enzyme was found to be expressed in a developmental stage-dependent manner, being at a very low level in liver samples from 1-day-old mice and then gradually increasing to the maximum level in liver samples from 4-week-old mice.

Molecular cloning, expression, and functional characterization of novel mouse sulfotransferases

Nucleotide sequences of two mouse cDNAs encoding new sulfotransferase enzymes were determined. Analysis of the deduced amino acid sequences revealed that one represents a novel member of the phenol sulfotransferase family and the other is highly homologous to human SULT2B1 hydroxysteroid sulfotransferases. The recombinant enzymes, transiently expressed in COS-7 cells, were characterized with respect to their substrate specificity using a variety of substrates for different types of sulfotransferases. The tissue-specific expression of these two new mouse sulfotransferases was examined by Northern blot analysis.

cDNA cloning, expression, and characterization of the human bifunctional ATP sulfurylase/adenosine 5'-phosphosulfate kinase enzyme

A cDNA encoding the human bifunctional ATP sulfurylase/adenosine 5'-phosphosulfate (APS) kinase was cloned and sequenced. The enzyme contains an APS kinase domain in its N-terminal portion and an ATP sulfurylase domain in its C-terminal portion. Recombinant full-length enzyme and its constituent APS kinase and ATP sulfurylase domains were individually expressed, purified, and shown to have their respective enzymatic activities.

Localization and functional analysis of the substrate specificity/catalytic domains of human M-form and P-form phenol sulfotransferases

Human monoamine (M)-form and simple phenol (P)-form phenol sulfotransferases (PSTs), which are greater than 93% identical in their primary sequences, were used as models for investigating the structural determinants responsible for their distinct substrate specificity and other enzymatic properties. A series of chimeric PSTs were constructed by reciprocal exchanges of DNA segments between cDNAs encoding M-form and P-form PSTs. Functional characterization of the recombinant wild-type M-form, P-form, and chimeric PSTs expressed in Escherichia coli and purified to homogeneity revealed that internal domain-spanning amino acid residues 84-148 contain the structural determinants for the substrate specificity of either M-form or P-form PST. Data on the kinetic constants (Km, Vmax, and Vmax/Km) further showed the differential roles of the two highly variable regions (Region I spanning amino acid residues 84-89 and Region II spanning amino acid residues 143-148) in substrate binding, catalysis, and sensitivity to the inhibition by 2,6-dichloro-4-nitrophenol. In contrast to the differential sulfotransferase activities of M-form and P-form PSTs toward dopamine and p-nitrophenol, the Dopa/tyrosine sulfotransferase activities were found to be restricted to M-form, but not P-form, PST. Furthermore, the variable Region II of M-form PST appeared to play a predominant role in determining the Dopa/tyrosine sulfotransferase activities of chimeric PSTs. Kinetic studies indicated the role of manganese ions in dramatically enhancing the binding of D-p-tyrosine to wild-type M-form PST. Taken together, these results pinpoint unequivocally the sequence encompassing amino acid residues 84-148 to be the substrate specificity/catalytic domain of both M-form and P-form PSTs and indicate the importance of the variable Regions I and II in determining their distinct enzymatic properties.

Direct assessment of small airways reactivity in human subjects

Our knowledge of airways reactivity to inflammatory agonists is derived predominantly from tests dominated by large airway responsiveness. To determine directly, the histamine responsiveness of the smallest airways, eight normal and 11 asymptomatic asthmatic subjects were studied utilizing a wedged bronchoscope technique. A fiberoptic bronchoscope was wedged in the anterior segment of the right upper lobe and a double-lumen catheter was advanced through the working channel to its tip. With a constant flow of gas (5% CO2 in air) through one lumen of the catheter, pressure at the tip of the bronchoscope was measured with the subject breath-holding at FRC. Peripheral airways resistance (Rp) was measured at baseline and after saline, histamine (10, 50, 100 mg/ml) and isoproterenol (2 mg/ml) challenge through the bronchoscope. Baseline Rp of asthmatics (0.041 +/- 0.015 cm H2O/ml/min; mean +/- SE) was significantly greater than normal subjects (0.011 +/- 0.003 cm H2O/ml/min; p = 0.019). The log of the concentration of histamine that caused a 100% increase in peripheral airways response was greater in the normal subjects than in the asthmatic subjects (p = 0.0114) and correlated with whole lung responsiveness to histamine in asthmatics (r = 0.847, p < 0.05). Isoproterenol reversed completely the increase in Rp in normal subjects but not asthmatic subjects. The results of this study demonstrate that the resistance of the smallest peripheral airways, when measured directly, increased when challenged locally with histamine in both normal subjects and asthmatic subjects. However, the peripheral airways responsiveness was significantly enhanced in asthmatic subjects relative to normal controls.

Ragweed-specific antibodies in bronchoalveolar lavage fluids and serum before and after segmental lung challenge: IgE and IgA associated with eosinophil degranulation

BACKGROUND

Migration of eosinophils and release of eosinophil degranulation products into bronchoalveolar lavage fluid is a consistent finding in studies of late responses to allergen challenge in the lung. However, the mechanism of eosinophil activation and release of eosinophil products in vivo is unclear.

OBJECTIVE

We investigated the hypothesis that antigen-specific IgG, IgA, secretory IgA, or IgE is responsible for the eosinophil activation observed in the late-phase pulmonary reaction.

METHODS

Ragweed-specific IgE, IgA, secretory IgA, and IgG were measured by monoclonal antibody-based immunoassays in bronchoalveolar lavage (BAL) fluid and in serum from 19 asthmatic subjects allergic to ragweed and six healthy nonallergic control subjects before and 20 hours after segmental lung challenge with ragweed extract. Eosinophil cationic protein (ECP) was also measured in BAL fluid as a marker of eosinophil activation.

RESULTS

Most allergic asthmatic subjects had detectable levels of ragweed-specific IgE, IgA, and IgG in their serum and BAL fluid, whereas normal subjects had ragweed-specific IgA with no ragweed-specific IgE and little ragweed-specific IgG. IgA was the dominant ragweed-specific antibody isotype in BAL fluids. Ragweed-specific sIgA (r[s] = 0.52, p = 0.02) and IgA (r[s] = 0.50, p = 0.03) in BAL fluid after segmental lung challenge were significantly correlated with ECP. Ragweed-specific IgE and IgA in serum also correlated with ECP (r[s] = 0.74, p < 0.001 and r[s] = 0.48, p = 0.04, respectively).

CONCLUSIONS

The correlation of allergen-specific IgA and IgE antibody levels with ECP as a marker of eosinophil degranulation suggests an important role for IgE antibodies in allergic pulmonary inflammation and a potential role for antigen-specific IgA in eosinophil degranulation in the lung after antigen challenge.

The benefit and risk of postmastectomy radiation therapy in patients with high-risk breast cancer

To evaluate the efficacy of postmastectomy radiation therapy (PMRT) for prophylaxis against locoregional recurrence in high-risk breast cancer patients, and the rate of complication associated with such treatment, we retrospectively reviewed 79 breast cancers in 78 patients, who were given therapy (PMRT) between April 1990 and March 1995. Radiation doses were 46-50 Gy in 2-Gy fractions. High-risk factors included primary tumor (> or = 5 cm) in 19 (24.1%) patients, positive axillary lymph nodes (> or = 4) in 56 (70.9%) patients, positive or close (< or = 2 mm) surgical margins in 14 (17.7%) patients, and central or inner quadrant tumor with positive axillary nodes and lymphovascular invasion in seven (8.9%) patients. Adjuvant chemotherapy was also given to 69 of 78 (88.5%), patients and hormonal therapy to 41 of 78 (53.7%) patients. The median follow-up time was 25 months (range, 7-66 months) after mastectomy. Our study revealed that locoregional failure as the first site of failure occurred in only one of 78 (1.3%) patients. Relapse-free survival at 3 years was 67.7% [95% confidence interval (CI), 52.0-81.3], and overall survival was 76.9% (95% CI, 63.3-90.6). The incidence of radiological evidence of lung fibrosis increased significantly in patients whose internal mammary chain was included in the radiation field. The occurrence of lung fibrosis can be reduced by changing radiation treatment technique and keeping central lung distance (CLD) of tangential field to < or = 2.8 cm in tangential field technique or < or = 1.4 cm in tangential with a separate internal mammary field technique. We concluded that the risk of locoregional recurrence in high-risk breast cancer patients can be much reduced by PMRT. With careful selection of radiation treatment fields, radiotherapy technique, and limitation of CLD to < or = 2.8 cm in tangential technique or < or = 1.4 cm in separate technique, the risk of symptomatic radiation pneumonitis is minimal. PMRT should be recommended for breast cancer patients who are at high risk for locoregional recurrence.

Protein SRP54 of human signal recognition particle: cloning, expression, and comparative analysis of functional sites

Signal recognition particle (SRP) plays a critical role in the targeting of secretory proteins to cellular membranes. An essential component of SRP is the protein SRP54, which interacts not only with the nascent signal peptide, but also with the SRP RNA. To understand better how protein targeting occurs in the human system, the human SRP54 gene was cloned, sequenced, and the protein was expressed in bacteria and insect cells. Recombinant SRP54 was purified from both sources. The protein bound to SRP RNA in the presence of protein SRP19, and associated with the signal peptide of in vitro translated pre-prolactin. Comparative sequence analysis of human SRP54 with homologs from all three phylogenetic domains was combined with high-stringency protein secondary structure prediction. A conserved RNA-binding loop was predicted in the largely helical M-domain of SRP54. Contrary to general belief, the unusually high number of methionine residues clustered outside the predicted helices, thus indicating a mechanism of signal peptide recognition that may involve methionine-rich loops.

Preoperative concurrent chemotherapy and radiotherapy in rectal cancer patients

The management of rectal cancer has changed significantly in recent years. The key end-point is no longer survival but rather preservation of sphincter function with improved quality of life. Preoperative radiation can not only render a low-lying rectal tumor amenable to sphincter-preserving surgery but has also been reported to give better local control and lower toxicity than postoperative radiotherapy. From October 1991 through July 1996, 46 patients with local advanced or low-lying rectal cancer were treated with preoperative high-dose radiotherapy and concurrent chemotherapy. All patients underwent pelvic radiotherapy with 5,000 to 5,400 cGy in 25 to 27 fractions. Chemotherapy was given concomitantly and consisted of two courses of 5-fluorouracil (5-FU) at 1,000 mg/m2 for 4 days in week 1 and week 5 plus mitomycin C 10 mg/m2 single bolus on day 1 of week 1. In 30 patients, postoperative adjuvant chemotherapy with 5-FU and levamisole weekly was also given, for a total of 12 months. The most common acute toxicity was grade 1 to 2 diarrhea and tenesmus during radiation or soon afterward. Only five of the 46 patients experienced symptomatic grade 3 acute toxicity. Forty-two patients underwent subsequent surgery 6 to 8 weeks after concurrent chemoradiotherapy. Pathologic examination disclosed complete tumor regression in eight patients and microscopic residual disease in 13 patients after preoperative chemoradiation. Of the 42 patients who completed the intended treatments, only one had local recurrence. The sphincter was preserved in 21 of the 26 patients in whom the tumor was located within 5 cm above the anal verge. Twelve of the 16 evaluable patients had good to excellent sphincter function. The 2-year overall survival rate was 93% and the disease-free survival was 81%. Our findings indicate that preoperative concurrent chemoradiotherapy not only allows low-lying rectal tumors to be resected while preserving sphincter function but also results in good local control and acceptable toxicity.

Overexpression of the multidrug resistance genes mdr1, mdr3, and mrp in L1210 leukemia cells resistant to inhibitors of ribonucleotide reductase

L1210 MQ-580 is a murine leukemia cell line resistant to the cytotoxic activity of the alpha-(N)-heterocyclic carboxaldehyde thiosemicarbazone class of inhibitors of ribonucleotide reductase. The line is cross-resistant to etoposide, daunomycin, and vinblastine. L1210 MQ-580 cells expressed 8-fold resistance to 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP), a relatively newly developed inhibitor of ribonucleotide reductase. The accumulation of [14C]3-AP by L1210 MQ-580 cells was 5- to 6-fold less than by parental L1210 cells. An increased rate of efflux of 3-AP was responsible for the lower steady-state concentration of 3-AP in resistant cells. In reverse transcription-polymerase chain reaction assays, L1210 MQ-580 cells were found to overexpress the multidrug resistance genes mdr1, mdr3, and mrp, but not the mdr2 gene, compared with parental L1210 cells. Measurement of the steady-state concentration of doxorubicin, a potential substrate for both the mdr and mrp gene products, demonstrated that L1210 MQ-580 cells accumulated 4-fold less anthracycline than parental cells. These findings indicate that drug efflux is a major determinant of the pattern of cross-resistance of L1210 MQ-580 cells. To extrapolate these observations to the human homologues of the mdr1, mdr3, and mrp murine genes, the effects of 3-AP were measured in L1210/VMDRC0.06 and NIH3T3 36-8-32 cells transfected with human MDR1 and MRP cDNAs, respectively. The transfectants were 2- to 3-fold resistant to the cytotoxic effects of 3-AP and accumulated less [14C]3-AP than their parental mock-transfected counterparts. Moreover, the cytotoxic activity of 3-AP was significantly greater in two double mrp gene knockout cell lines than in parental W 9.5 embryonic stem cells. Thus, the results suggest that 3-AP is a substrate for both the P-glycoprotein and MRP and that baseline MRP expression has the capacity to exert a protective role against the toxicity of this agent.

Characterization of bovine heart sulfotransferase catalyzing the sulfation of tyrosine-containing peptides

Using [35S]PAPS as the sulfate donor, we have detected a sulfotransferase from bovine heart which catalyzes the sulfation of tyrosine-containing peptides. The enzyme displayed optimal activity at pH 5.75 and 35 degrees C in a one-hour reaction. The addition of 10 mM Mn2+ or Co2+ to the reaction mixture increased the sulfotransferase activity by 3.4- and 3.5-fold, respectively. In contrast, the maximum increment stimulated by Mg2+ was only 1.75-fold at 15 mM concentration, and instead of exerting an enhancement effect, Ca2+ was found to be a potent inhibitor. The addition of 50 mM NaF to the reaction mixture resulted in an increase in sulfotransferase activity of 3.3-fold. The K(m) for 3'-phosphoadenosine 5'-phosphosulfate (PAPS) was determined to be 2 microM at a constant 0.5 mM Boc-Glu-Asp-Tyr-Val. Among the 10 peptides tested as substrates, Boc-Glu-Asp-Tyr-Val and Boc-Asp-Asp-Tyr-Val provided the highest activities.

Clonal chromosomal abnormalities as direct evidence for clonality in nasal T/natural killer cell lymphomas

Nasal T/natural killer (NK) cell lymphoma is a distinct clinicopathologic entity which is more prevalent in Asia than in America and Europe. The clonal nature of the infiltrating lymphoid cells is difficult to demonstrate because of the lack of immunologic markers for clonality and the absence of clonal T-cell receptor gene rearrangement in most cases. In this study, clonal chromosomal abnormalities were detected in the tumour cells from four patients with nasal T/NK cell lymphoma. This finding provided direct evidence for clonality of the disease. Moreover, nonrandom cytogenetic abnormalities, including isochromosome for the short arm (p) of chromosome 6, isochromosome for the long arm (q) of chromosome 1, partial deletion of 6q, and aberrations at 11q, were disclosed. Isochromosome 6p was the sole structural abnormality in one patient, which may be a pathognomonic change in nasal lymphoma.

Tissue-specific and developmental stage-dependent expression of a novel rat Dopa/tyrosine sulfotransferase

Tissue-specific and developmental stage-dependent expression of a novel Dopa/tyrosine sulfotransferase in Sprague-Dawley rats was examined. Both immunoblot and Northern blot analyses showed that the enzyme was expressed predominantly in liver and to a lesser extent in kidney. Its expression could not be detected in nine other organs tested. Livers from different age groups of male or female rats were examined for the developmental regulation of the expression of the Dopa/tyrosine sulfotransferase. Results from immunoblot and Northern blot analyses revealed that the enzyme was present at a very low level in livers of 1-day-old to 2-week-old rats, and gradually increased to a maximum level in rats older than 2 months. Data from the enzymatic assays also showed a similar trend of expression in both male and female rats. The Dopa/tyrosine sulfotransferase activities detected in liver samples of the 8-week-old male and female rats were, respectively, 8.6 and 6.6 times that of the activities detected in liver samples of the 1-day-old male and female rats. These data provide a foundation for the future investigation of the cis- and trans-acting factors involved in the regulation of the tissue-specific and developmental stage-dependent expression of this enzyme.

Concomitant chemotherapy and radiotherapy for locally advanced nasopharyngeal carcinoma

BACKGROUND

The prognosis of stage III and IV nasopharyngeal carcinoma treated with radiation therapy alone is poor. To improve outcome, concomitant chemotherapy was incorporated into the treatment of locally advanced nasopharyngeal carcinoma.

METHODS AND PATIENTS

Seventy-four patients with locally advanced nasopharyngeal carcinoma were prospectively treated with a combination of concomitant chemotherapy and computerized-tomography-assisted radiotherapy at Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan, between April 1990 and December 1995. The first 29 patients who had a minimum of 2 years of follow-up were included in this report. Their median interval of follow-up was 42 months. The dose of radiation was 7000 cGy given in 35 fractions. Two courses of chemotherapy, consisting of cisplatin and 5-fluorouracil, were delivered simultaneously with radiotherapy during weeks 1 and 6, and two additional monthly courses were given after radiotherapy. Included in this study were four patients with stage III and 25 patients with stage IV disease.

RESULTS

Toxicities of concomitant radiotherapy and chemotherapy were acceptable and reversible. The locoregional control rate at 50 months was 88.2%, and the disease-free survival rate was 74.6%.

DISCUSSION

Our results demonstrate an improved survival with the addition of computerized tomography treatment planning and concomitant chemotherapy to radiotherapy in the treatment of locally advanced nasopharyngeal carcinoma when compared with data in the current literature. However, a randomized trial comparing computerized-tomography-assisted radiotherapy with and without chemotherapy is necessary to confirm the contribution of chemotherapy.

Phenotypic analysis of alveolar macrophages and monocytes in allergic airway inflammation. I. Evidence for activation of alveolar macrophages, but not peripheral blood monocytes, in subjects with allergic rhinitis and asthma

Macrophages and monocytes play important proinflammatory roles in allergic inflammation. We hypothesized that these cells would express an activated phenotype in allergic disease of the airways. We therefore compared the expression of 17 activation markers on the surface of alveolar macrophages (AM) and peripheral blood monocytes (PBM) in 13 subjects with asymptomatic allergic asthma (AA), nine subjects with asymptomatic allergic rhinitis (AR), and 11 nonallergic (N). AM were obtained by BAL, and PBM were simultaneously obtained by phlebotomy; both were analyzed for expression of surface markers using a new two-color flow cytometry method that essentially eliminates background autofluorescence. The proportions of AM in BAL fluid from AA, AR, and N subjects were 84 +/- 2, 85 +/- 4, and 91 +/- 1%, respectively; viability always exceeded 92%. Expression of eight markers (CD16, CD18, CD32, CD44, CD71, HLA Class I, HLA DR, and HLA DQ) was significantly (p < 0.05) higher on AM of AA than on N; expression of six markers (CD11a, CD16, CD18, CD71, HLA Class I, and HLA DR) was higher on AM of AR than on N, with differences in CD44 levels approaching statistical significance (p = 0.07). Expression of one marker, CD44, was significantly higher on AM of AA than on those of AR, with differences in HLA Class I levels approaching statistical significance (p = 0.07). In contrast, no significant differences were found among the three groups in the expression in eight other markers (CD11b, CD14, CD23, CD29, CD33, CD35, CD63, and CD64). Finally, similar analysis of PBM from these same subjects failed to find any difference between the three groups in any of the 17 activation markers studied. These data suggest that AM are activated in allergic respiratory diseases, and that levels of HLA Class I and CD44 on AM are altered during allergic inflammation in the upper and lower airways.

Manganese-dependent Dopa/tyrosine sulfation in HepG2 human hepatoma cells: novel Dopa/tyrosine sulfotransferase activities associated with the human monoamine-form phenol sulfotransferase

Human monoamine (M)-form phenol sulfotransferase (PST) was PCR-cloned and transiently expressed in COS-7 cells. The recombinant enzyme was demonstrated to display not only the previously reported sulfotransferase activity toward dopamine, but also novel manganese-dependent Dopa/tyrosine sulfotransferase activities. These results imply a new functional role of the human M-form PST in the homeostatic regulation of Dopa and tyrosine.

Increased NM23: MTS1 ratio inversely correlated with metastasis behaviour in human lung squamous cell carcinoma

The nm23 and mts1 genes have been the focus of attention as regards the association of their expression with metastatic behaviour. The level of nm23 and mts1 gene products has been demonstrated to correlate with metastatic potential in some tumors, but not in all. Here we show that these two genes might be coregulated and the ratio of their expression correlated with metastatic behaviour. Western blot analysis showed that the expression of both NM23 and MTS1 proteins was reduced in human lung cancer CH27 cells by retinoic acid treatment, but the ratio of NM23: MTS1 increased in a dose-dependent manner. Results also exhibited that retinoic acid altered the microtubule assembly of CH27 cells and reduced the metastatic ability of the cells in vitro. These data suggest that the metastatic potential of CH27 cells may be related to the relative expression of these two genes, and that their pathway in regulating metastatsis might be linked.

Acute and chronic effects of a 5-lipoxygenase inhibitor in asthma: a 6-month randomized multicenter trial. Zileuton Study Group

BACKGROUND

Leukotrienes produced by the 5-lipoxygenase pathway of arachidonic acid metabolism may mediate bronchoconstriction and inflammatory changes important in the pathophysiology of asthma. Leukotriene inhibition may be effective in asthma management.

OBJECTIVE

This clinical trial was performed to assess the long-term efficacy and safety of zileuton, an inhibitor of 5-lipoxygenase.

METHODS

In this multicenter, double-blind, parallel-group, placebo-controlled trial, 600 mg of zileuton, 400 mg of zileuton, or placebo was given orally, each four times daily for 6 months. Patients with mild to moderate asthma (n = 373), 18 to 62 years of age, being managed with regularly inhaled beta-agonist alone, were randomized to the zileuton or placebo groups (n = 122 to 126). Outcome measures included serial spirometry, daily peak expiratory flow rates, daytime and nocturnal symptoms, frequency of beta-agonist use, and number of asthma exacerbations treated with systemic corticosteroids.

RESULTS

An acute bronchodilatory effect was observed 2 to 5 hours after the initial dose of medication in both 400 mg zileuton and 600 mg zileuton groups compared to the placebo group. Both zileuton groups had significantly greater improvements in FEV1 than did the placebo group by day 8. On day 36, FEV1 improved 16% and 12% from baseline for patients treated with 600 mg zileuton and 400 mg zileuton, respectively, compared with an improvement of 6% for the placebo-treated group (p < 0.01, zileuton 600 mg vs placebo). Blood eosinophil levels were significantly reduced in both zileuton-treated groups compared with the placebo group. In the group receiving 600 mg zileuton, morning peak expiratory flow rate improved by 7% to 10%; daytime and nocturnal symptoms decreased by 37% and 31%, respectively; beta-agonist use decreased by 31%; and the proportion of patients requiring steroid rescue medication during the study was reduced by 62% (p < 0.05 for all comparisons of zileuton, 600 mg, vs placebo). Improvements were sustained over 6 months. Adverse events were similar in the three groups with no apparent, dose-related side effects.

CONCLUSION

Zileuton produces objective and subjective improvements in patients with mild to moderate asthma and is well tolerated.

Dissociation of bradykinin-induced plasma exudation and reactivity in the peripheral airways

To determine if bradykinin, a potential mediator of asthma, acts, at least in part, at the level of the peripheral airways, we used a wedged bronchoscope technique to study asthmatic and normal subjects. Baseline peripheral airways resistance (Rp) was measured in the right upper lobe. Subjects then received saline, followed by increasing doses of bradykinin, aerosolized through the bronchoscope. Rp was measured after each challenge. At the end of the procedure, bronchoalveolar lavage was performed in both the challenged and a control segment. Fibrinogen content of recovered lavage fluids was measured as an index of plasma exudation. Bradykinin induced a dose-dependent increase in Rp in the asthmatics, but did not effect Rp in normal subjects. In asthmatics, there was no significant correlation between peripheral airways reactivity and whole lung reactivity to bradykinin. Fibronogen increased significantly in both groups after bradykinin challenge, and there was no significant difference between postchallenge levels for the two groups. Thus, hyperreactivity of the peripheral airways in asthmatics is not directly due to plasma exudation. The ability of bradykinin to increase peripheral airways resistance in asthmatic, but not in normal, subjects is consistent with a role of this peptide as a mediator of asthma.

Synthesis and biological activity of 3- and 5-amino derivatives of pyridine-2-carboxaldehyde thiosemicarbazone

A series of 3- and 5-alkylamino derivatives, as well as other structurally modified analogues of pyridine-2-carboxaldehyde thiosemicarbazone, have been synthesized and evaluated as inhibitors of CDP reductase activity and for their cytotoxicity in vitro and antineoplastic activity in vivo against the L1210 leukemia. Alkylation of 3- and 5-amino-2-(1,3-dioxolan-2-yl)pyridines (1, 2) resulted in corresponding 3-methylamino, 5-methylamino, 3-allylamino, 5-ethylamino, 5-allylamino, 5-propylamino, and 5-butylamino derivatives (5, 6, and 11-15), which were then condensed with thiosemicarbazide to yield the respective thiosemicarbazones (7, 8, and 16-20). Oxidation of 3,5-dinitro-2-methylpyridine (21) with selenium dioxide, followed by treatment with ethylene glycol and p-toluenesulfonic acid, produced the cyclic ethylene acetal, 23. Oxidation of 2-(1,3-dioxolan-2-yl)-4-methyl-5-nitropyridine (26) with selenium dioxide, followed by sequential treatment with sodium borohydride, methanesulfonyl chloride, and morpholine afforded the morpholinomethyl derivative 30. Catalytic hydrogenation of 23 and 30 with Pd/C yielded the corresponding amino derivatives 24 and 31. Catalytic hydrogenation of 5-cyano-2-methylpyridine (33) with Raney nickel, followed by treatment with acetic anhydride, gave the amide derivative 35. N-Oxidation of 35, followed by rearrangement with acetic anhydride, produced the acetate derivative, 5-[(acetylamino)methyl]-2-(acetoxymethyl)pyridine (37). Repetition of the N-oxidation and rearrangement procedures with compound 37 yielded the diacetate derivative 39. Condensation of compounds 24, 31, and 39 with thiosemicarbazide afforded the respective 3,5-diaminopyridine-, 4-(4-morpholinylmethyl)-5-aminopyridine-, and 5-(aminomethyl)pyridine-2-carboxaldehyde thiosemicarbazones (25, 32, and 40). The most biologically active compounds synthesized were the 5-(methylamino)-, 5-(ethylamino)-, and 5-(allylamino)pyridine-2-carboxaldehyde thiosemicarbazones (8, 17, and 18), which were potent inhibitors of ribonucleotide reductase activity with corresponding IC50 values of 1.3, 1.0, and 1.4 microM and which produced significant prolongation of the survival time of L1210 leukemia-bearing mice, with corresponding optimum % T/C values of 223, 204, and 215 being obtained when administered twice daily for six consecutive days at dosages of 60, 80, and 80 mg/kg, respectively.

Enhanced expression of IL-12 associated with Th1 cytokine profiles in active pulmonary sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown etiology characterized by the expansion of activated oligoclonal CD4+ T cells and macrophages at sites of disease. To investigate the immunopathogenesis of sarcoidosis, we analyzed patterns of cytokine expression in bronchoalveolar lavage cells and fluid from patients with pulmonary sarcoidosis and idiopathic pulmonary fibrosis and from normal volunteers. We found dominant type 1 cytokine expression, with elevated mRNA and protein levels of IFN-gamma, but not IL-4, in sarcoid lung cells and fluid compared with those in normal samples. To define immunoregulatory mechanisms important to this type 1 response, we analyzed the expression of IL-12 and IL-10 in lung cells and fluid. Using semiquantitative PCR, we found significantly higher mRNA expression of the regulated IL-12 p40 subunit, but not IL-10, in sarcoid compared with normal lung cells. Consistent with these observations, strikingly elevated levels of p40 protein were found in sarcoid compared with normal bronchoalveolar lavage fluid. Unstimulated and Staphylococcus aureus-stimulated sarcoid alveolar macrophages produced greater amounts of IL-12 than normal alveolar macrophages when cultured in vitro. We hypothesize that sarcoidosis is a Th1-mediated disease driven by chronic, dysregulated production of IL-12 at sites of disease.

Enhanced expression of IL-12 associated with Th1 cytokine profiles in active pulmonary sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown etiology characterized by the expansion of activated oligoclonal CD4+ T cells and macrophages at sites of disease. To investigate the immunopathogenesis of sarcoidosis, we analyzed patterns of cytokine expression in bronchoalveolar lavage cells and fluid from patients with pulmonary sarcoidosis and idiopathic pulmonary fibrosis and from normal volunteers. We found dominant type 1 cytokine expression, with elevated mRNA and protein levels of IFN-gamma, but not IL-4, in sarcoid lung cells and fluid compared with those in normal samples. To define immunoregulatory mechanisms important to this type 1 response, we analyzed the expression of IL-12 and IL-10 in lung cells and fluid. Using semiquantitative PCR, we found significantly higher mRNA expression of the regulated IL-12 p40 subunit, but not IL-10, in sarcoid compared with normal lung cells. Consistent with these observations, strikingly elevated levels of p40 protein were found in sarcoid compared with normal bronchoalveolar lavage fluid. Unstimulated and Staphylococcus aureus-stimulated sarcoid alveolar macrophages produced greater amounts of IL-12 than normal alveolar macrophages when cultured in vitro. We hypothesize that sarcoidosis is a Th1-mediated disease driven by chronic, dysregulated production of IL-12 at sites of disease.