The clinical efficacy of intratumoral OK-432 administration in advanced cancer patients

The clinical efficacy of intratumoral (IT) OK-432 immunotherapy in advanced cancer patients was investigated. Furthermore, the infiltration of lymphocyte subsets into the tumor tissues after the IT administration of OK-432 was also immunohistologically examined in order to analyze the mechanism of action of OK-432 immunotherapy. Forty-four patients with advanced cancer were treated with IT OK-432 immunotherapy. Ten KE (1 mg) of OK-432 was given either daily or on every second day and repeated as often as possible, the mean frequency of OK-432 injections being 18.1±14.5 times, ranging between 5 and 25 administrations. Thirty-one of the 44 patients were evaluable, 3 of whom (9.7 per cent) developed a partial response and 5 (16.1 per cent) a minor response. Intratumoral OK-432 immunotherapy, however, did not necessarily prolong the survival time. Leu 1, 3 and 7 reactive cells infiltrated into the tumor tissues treated by OK-432 injection, more frequently, when compared with cells which had been treated by recombinant TNF injection. Thus, it was suggested that IT OK-432 immunotherapy might be effective for the local control of tumor growth through the host mediated action, and that, in combination with systemic therapy, may enhance the clinical effects and prolong the survival time in advanced cancer patients.     

The clinical efficacy of intratumoral OK-432 administration in advanced cancer patients

The clinical efficacy of intratumoral (IT) OK-432 immunotherapy in advanced cancer patients was investigated. Furthermore, the infiltration of lymphocyte subsets into the tumor tissues after the IT administration of OK-432 was also immunohistologically examined in order to analyze the mechanism of action of OK-432 immunotherapy. Forty-four patients with advanced cancer were treated with IT OK-432 immunotherapy. Ten KE (1 mg) of OK-432 was given either daily or on every second day and repeated as often as possible, the mean frequency of OK-432 injections being 18.1 +/- 14.5 times, ranging between 5 and 25 administrations. Thirty-one of the 44 patients were evaluable, 3 of whom (9.7 per cent) developed a partial response and 5 (16.1 per cent) a minor response. Intratumoral OK-432 immunotherapy, however, did not necessarily prolong the survival time. Leu 1, 3 and 7 reactive cells infiltrated into the tumor tissues treated by OK-432 injection, more frequently, when compared with cells which had been treated by recombinant TNF injection. Thus, it was suggested that IT OK-432 immunotherapy might be effective for the local control of tumor growth through the host mediated action, and that, in combination with systemic therapy, may enhance the clinical effects and prolong the survival time in advanced cancer patients.     

Clinical studies on streptococcal preparation (OK-432) combined with mitomycin-C, 5-FU and cytosine arabinoside in advanced cancer patients.

Streptococcal preparation (OK-432), a new type of anti-cancer agent, was given to the patients with advanced cancer in combination with Mitomycin-C, 5-FU and Cytosine arabinoside. OK-432 was administered intramuscularly with a daily dose of 2.0 KE consecutively or locally into the tumor with a large-dose of 100 KE. Most cases tolerated the long term administration of OK-432 without any severe side effects and the highest dose reached was 314 KE during 161 days of treatment. Of the 53 patients evaluated, 31 were given the initial large dose intratumoral OK-432. Thirteen were judged 0-C and Category 1 according to the Karnofsky criteria for a response rate of 44.8 per cent as compared with 12.5 per cent in the group without the initial large-dose administration.     

Correlation between anti-tumor effect and delayed hypersensitivity induced by topically applied OK-432 with histological findings

Delayed hypersensitivity (DH) against OK-432 was induced in BALB/c mice by injecting 2 KE of OK-432 with Freund's incomplete adjuvant into foot pads. One week after presensitization with OK-432, 2 X 10(5) cells of Meth A tumor were implanted subcutaneously in all mice, followed by intratumoral injection of 1 KE of OK-432 five times every other day starting at 7th day in experimental group. Tumor growth was significantly inhibited in the OK-432 presensitized group comparing to non-sensitized group. In experimental groups marked inhibition was observed in mice which were injected with OK-432 intratumorally 2 to 3 weeks after presensitization. This effect correlated well with delayed hypersensitivity against OK-432. Histological changes after intratumoral injection of OK-432 were examined in order to analyse the mechanism of this effect. The main finding of OK-432 injected specimen by H.E. staining were degeneration of tumor cells and infiltration of inflammatory cells. These changes were stronger in OK-432 presensitized mice. By beta-D-galactosidase staining accumulation of macrophages was found both inside the tumor and the surrounding tissue, and these macrophages increased in OK-432 presensitized mice. Immunoperoxidase staining with antiasialo GM1 anti-serum was also performed. Greater number of activate macrophages were observed to accumulate in the specimen of OK-432 presensitized mice than that of control mice. Some T cells were observed only around tumor tissues and not in the tumor of both presensitized and unsensitized mice. These results suggest that the activated macrophages play a major role in the augmentation of antitumor effect by presensitization with OK-432.     

Experimental study concerning safety dosage of OK-432 for intrauterine treatment

OBJECTIVE: Clinical intrauterine treatment for fetal cystic hygroma has so far been performed in a few patients; however, it is still difficult to evaluate the results. The aim of this study is to establish the safe dosage of OK-432 in the intrauterine treatment of fetal cystic hygroma. METHODS: OK-432 was injected either subcutaneously behind the neck of the fetuses or into the amniotic cavity through the uterine wall of pregnant Japanese white rabbits at 27 days of gestation. Saline was administered to the controls. The dosage and the site of injection were as follows: group 1, OK-432, 0.01 KE (0.25 KE/kg) in 0.2 mL saline per fetus, subcutis; group 2, OK-432, 0.02 KE (0.5 KE/kg) in 0.2 mL saline per fetus, subcutis; group 3, OK-432, 0.04 KE (1 KE/kg) in 0.2 mL saline per fetus, subcutis; group 4, OK-432, 0.01 KE in 0.2 mL saline per fetus, amniotic cavity; group 5, OK-432, 0.04 KE in 0.2 mL saline per fetus, amniotic cavity; group 6, saline, 0.2 mL per fetus, subcutis; group 7, saline, 0.2 mL per fetus, amniotic cavity. All fetuses were delivered at 29 days of gestation. RESULTS: The mother's rectal temperature was mostly in the normal range throughout the experiment. There was no significant difference between any of the seven groups in fetal body weight. The C reactive protein values of all fetuses were negative. The appearance of the skin of all the fetuses was normal. The histopathological findings of the skin in the OK-432 groups showed a moderate infiltration of monocytes and plasma cells. No pathological changes were observed in the heart, lung, liver or kidneys of any of the fetuses. CONCLUSION: Based on this rabbit experiment, we determined that OK-432 may be safely used at a dose of up to 1 KE/1 kg of fetal body weight as an intrauterine treatment for fetal cystic hygroma.     

Clinical studies on streptococcal preparation (OK-432) combined with mitomycin-C, 5-FU and cytosine arabinoside in advanced cancer patients

Streptococcal preparation (OK-432), a new type of anticancer agent, was given to the patients with advanced cancer in combination with Mitomycin-C, 5-FU and Cytosine arabinoside. OK-432 was administered intramuscularly with a daily dose of 2.0 KE consecutively or locally into the tumor with a large-dose of 100 KE. Most cases tolerated the long term administration of OK-432 without any severe side effects and the highest dose reached was 314 KE during 161 days of treatment. Of the 53 patients evaluated, 31 were given the initial large dose intratumoral OK-432. Thirteen were judged 0-C and Category 1 according to the Karnofsky criteria for a response rate of 44.8 per cent as compared with 12.5 per cent in the group without the initial large-dose administration.     

Experimental and clinical studies on the effect of reticuloendothelial system (RES) potentiator in the depressed RES function in cirrhotics

Among the patients with liver cirrhosis (LC) who undergo the operation, the postoperative complications are not infrequent and sometimes prove fatal. The impaired hepatic function, especially the impaired reticuloendothelial system (RES) function, has been claimed to be a possible pathogenic factor for these complications. The present experimental and clinical studies were undertaken to investigate the RES function and the effect of preoperative OK-432 administration as an RES potentiator in LC. The results are as follows: 1) CCl4-induced LC rats were evaluated for RES global phagocytic function, Kupffer cell phagocytic function, plasma opsonic activity and plasma opsonic substances such as fibronectin, C3 and IgG. All parameters except IgG showed significant depression compared to those values in normal rats. However, the administration of OK-432 (0.1 KE/rat, ip) improved all these depressed parameters. The OK-432 administration also significantly improved the survival following panperitonitis in LC rats. 2) Among 18 LC patients with hepatocellular carcinoma undergoing partial hepatectomy, the RES global phagocytic function, plasma opsonic activity and plasma opsonic substances were evaluated. Same as the experimental study, all parameters except IgG were significantly depressed among the LC patients compared to those values in the patients with normal liver. However, the preoperative OK-432 administration (5 KE/day sc for 4 days) significantly improved these parameters and consequently decreased the postoperative complications. These results indicate that the preoperative RES activation by the OK-432 was effective and useful for the prevention of the postoperative complications in the LC patients.     

A randomized controlled study to compare bladder instillation therapy of anticancer agents and combination therapy with OK-432 injection in prevention of post-TUR recurrence of bladder cancer

To evaluate the effects of bladder instillation chemotherapy of anticancer agents with OK-432 intradermal injection (group A) in preventing postoperative recurrence of bladder carcinoma, a randomized controlled study with intravesical instillation chemotherapy of anticancer agents (group B) as the reference standard was performed. As the anticancer agents, pepleomycin (PEP) was usually used at a concentration of 30 mg/30 ml physiological saline. OK-432 injection dose was gradually increased from 0.5 KE to 5.0 KE and maintenance dose was decided by local skin reactions. There were no differences in the patient's background factors between group A (22 cases) and group B (17 cases). The no-recurrence rate of bladder carcinoma was similar in the two groups, but the no-recurrence rate for the virgin tumor or the stage T0 cases was higher in group B. On the other hand, the values for the recurrent cases or the stage T1,2 cases was higher in group A. The SU-PS skin reaction as an immunological response was significantly higher in group A. There were no severe side effects derived from anticancer bladder instillation or OK-432 injection.     

OK-432 therapy for chylous pleural effusion or ascites associated with lymphatic malformations

OK-432 therapy is effective for the treatment of macrocystic lymphatic malformations (LMs), but the optimal management of patients with microcystic LMs associated with large chylous pleural effusions or chylous ascites is not resolved. We performed thoracoscopic- or laparoscopic-guided injection of OK-432 for 2 patients with diffuse microcystic LMs accompanied by refractory chylous pleural effusion or chylous ascites. Both cases responded well to OK-432 therapy with improvement/resolution of fluid collections and associated symptoms. We recommend the use of OK-432 therapy as a promising treatment for microcystic LMs with functionally significant lymphatic fluid collections.     

Clinical significance of immunotherapy for lung cancer--present and future

To evaluate the clinical efficacy of OK-432 immunotherapy as an surgical adjuvant for lung cancer patients, three kinds of randomized controlled trials were done. In the first trial, patients were randomized into two groups: an immunochemotherapy (IM-C) group and a chemotherapy (control) group. For IM-C group, OK-432 (2KE/w) was injected intramuscularly for three years. Significant improvement of the survival rates in the IM-C group was noted in the following items: all resected cases, stages I+II cases, stage III cases, completely resected cases, incompletely resected cases and cases with epidermoid carcinoma. However, in comparison to adenocarcinoma there was no significant difference between the two groups. In the second trial, patients were randomized into an intramuscular injection group and an intradermal injection group. In comparisons to the survival rates, there were no significant differences between the two groups. In the third trial, stage I patients were randomized into a group treated with intradermal injection (5KE/w) and no adjuvant group. To date, there was no significant difference between the two groups. It is concluded that OK-432 immunotherapy, with concomitant use of chemotherapy, have favourable effect on the patient with squamous cell carcinoma. No definitive difference of clinical effects between intramuscular injection and intradermal injection.     

Effect of biological response modifiers on a spontaneous murine renal cell carcinoma regression of metastases caused by the streptococcal preparation OK-432

The effect of the streptococcal preparation OK-432, which is one of the biological response modifiers, was examined in BALB/c mice using a transplantable murine renal cell carcinoma (Renca) of spontaneous origin, and an analysis of effector cells was performed. The tumor grew progressively and metastasized consistently to the abdominal lymph nodes and then to distant organs following the inoculation of Renca cells in the left renal subcapsular site in BALB/c mice, and the survival time of the mice was under 42 days. In this tumor model, i.p. administration of OK-432 after tumor inoculation significantly extended the survival time and significantly inhibited the formation of the inoculated tumor itself. Removal of the left kidney on the 7th day after tumor inoculation neither extended the survival time nor augmented the effect of OK-432. Splenic cells obtained on the 7th day after tumor inoculation from Renca-bearing mice treated with OK-432 were capable of lysing syngeneic Renca cells, NK-sensitive allogenic YAC-1 cells, and LAK-sensitive EL-4 cells in a 4-hour 51Cr-release assay in vitro. Those obtained from healthy mice treated with OK-432 also showed cytotoxic activity against Renca cells. The cytotoxicity of splenic cells from Renca-bearing mice treated with OK-432 was lost almost completely for both Renca and YAC-1 cells after in vitro treatment with anti-asialo GM1 antibody, and was partially lost after in vitro treatment with anti-Thy-1,2 antibody. Additionally, in vivo i.p. administration of anti-asialo GM1 antibody significantly counteracted the effect of OK-432 on survival. These findings demonstrated that Renca cells were NK-sensitive and that the i.p. administration of OK-432 was beneficial for the prevention of the spontaneous metastasis of Renca carcinoma. As the effectors, NK cells played a dominant role and activated T cells were also involved.     

Management of malignant ascites by intraperitoneal injection of OK-432. Possible mechanism of the reduction of original tumor mass volume

We studied the effect of intraperitoneal injection of OK-432 on the growth of original tumor mass in patients with malignant ascites and a possible mechanism of reduction of tumor volume. Sixteen patients with valuable original tumor mass and a large amount of ascites caused by gastro-intestinal cancer were studied. Tumor cells were separated from ascitic fluids and cultured in vitro before the study. Lymphocytes were collected from the fluids at varying intervals after intraperitoneal injection of OK-432 and cultured 24 hours in vitro. Effect of the culture supernatant on ascites-derived autologous tumor cell growth was examined in vitro using microplate assay. The results were as follows. 1) Reduction of tumor mass more than four weeks was found in 4 of 16 cases. 2) Before OK-432 injection, the culture supernatant from ascites-derived lymphocytes did not inhibit autotumor cell growth in vitro. But, the supernatant from lymphocytes which were collected from the ascites after OK-432 injection markedly inhibited tumor growth in all of 4 tumor mass reduction cases. In 12 non-reduction cases the supernatant slightly inhibited tumor growth only in 2 cases. 3) A similar growth inhibitory factor was detected in the mixed culture-supernatant of peripheral blood lymphocytes and OK-432 in vitro. 4) Preliminary studies indicated that the tumor growth inhibitory factor might be different from tumor necrosis factor and interferons. These results indicate that ascites-derived lymphocytes-producing factor may play an important role in reduction of tumor mass volume in patients with cancerous ascites.     

New approach to management of malignant ascites with streptococcal preparation OK-432. III. OK-432 attracts natural killer cells through a chemotactic factor released from activated neutrophils

When a streptococcal preparation, OK-432, was administered intraperitoneally to patients with malignant ascites, lymphocytes with cytotoxic activity against tumor cells increased in number in the peritoneal cavity after 5 to 7 days. To investigate the underlying mechanisms of such lymphocyte accumulation, lymphocyte chemotactic activity (LCA) in ascitic fluid was measured by a modification of the Boyden method. High LCA was found on the third and fourth days after the OK-432 injection. This LCA was generated in the cell-free supernatant of the patients' abdominal neutrophils that accumulated in the peritoneal cavity 24 hours after the injection of OK-432. A similar LCA was also found when normal peripheral neutrophils were incubated with OK-432. Incubation of normal neutrophils without OK-432 failed to generate LCA, however, and OK-432 alone had no LCA. We tentatively named this factor "neutrophil-derived lymphocyte chemotactic factor" (NDLCF). The NDLCF was heat stable and nondializable, and its molecular weight was approximately 45,000 daltons. It attracted mainly natural killer cells by immunoperoxidase assay of migrated lymphocytes in the chemotactic membrane. These characteristics were distinct from C5a, interleukin-1, and interleukin-2. The results suggest that the newly found NDLCF may be responsible for the infiltration of cytotoxic lymphocytes, especially natural killer cells in the peritoneal cavity in patients with malignant ascites when treated by intraperitoneal injections of OK-432.     

Induction and measurement of delayed hypersensitivity to OK-432

This study was performed intending to demonstrate whether delayed hypersensitivity (DH) to OK-432 might augment the antitumor effect of intratumoral injection of OK-432. In this preliminary report, we showed that 1) DH to OK-432 was inducible in BALB/c mice by injecting 2KE of OK-432 with Freund's incomplete adjuvant into foot pads 2) DH was assayed by direct macrophage migration inhibition test (MIT) of Harrington's microdroplet method using 100 micrograms/ml of Su-M protein extracted from OK-432 as in vitro test antigen 3) the highest MI was observed in the second week after sensitization 4) strong and stable DH was induced after the second sensitization at the interval of two weeks.     

Cytokine-mediated antitumor effect of OK-432 on urinary bladder tumor cells in vitro

Fatal complications from the intravesical instillation of bacillus Calmette-Guérin (BCG) for the treatment of superficial urinary bladder tumors have been reported. OK-432, an immunomodulating agent like BCG, may be an effective and safe agent for the treatment of urinary bladder tumors. We investigated the cytokine-mediated antitumor effect of OK-432 on established human bladder cancer cell lines (T24 and KK-47) in vitro. Peripheral blood mononuclear cells (PBMCs) from a healthy volunteer were cultured with OK-432 for various periods, and the culture supernatants were used as conditioned media. Cytokines in the culture supernatants were quantified. The antitumor effect of OK-432 was evaluated by colony-forming assays, using the conditioned media as the culture media. The colony survival of T24 and KK-47 cells was significantly inhibited by conditioned media from 24-h cultures of PBMCs incubated with OK-432 at concentrations of 0.05 and 0.1 Klinische Einheit (KE)/ml. Conditioned media from PBMCs cultivated with OK-432 for 7 days at 0.01 and 0.05 KE/ml also significantly inhibited the colony survival of both cell lines. Higher concentrations of interleukin-1 (IL-1) and tumor necrosis factor (TNF) were detected in conditioned media cultivated with OK-432 for 24 h than in media from PBMCs alone. However, higher concentrations of interferon (IFN) were detected in conditioned media cultivated with OK-432 for 7 days. Approximately 90% of the inhibition of KK-47 cells by the 24-h conditioned media was neutralized by an anti-TNF monoclonal antibody. The inhibition of T24 cells was neutralized approximately 50% by the same antibody. The inhibition of T24 and KK-47 cells by 7-day conditioned media was completely neutralized by an anti-IFN monoclonal antibody. The cultivation of PBMCs with OK-432 inhibited the production of granulocyte-colony-stimulating factor (G-CSF) by PBMCs. The inhibition may play a role in the mechanism of the antitumor effect of OK-432. Urinary bladder tumor cell lines have different sensitivities to cytokines. The cytokines induced by OK-432 vary with the concentration of OK-432 and the culture period. It is suggested that in intravesical instillation of OK-432 for treatment of urinary bladder tumor, the optimal dose and interval of instillation should be considered.     

Intratumoral injection of OK-432 in conjunction with fibrinogen greatly enhances antitumor effect on colorectal carcinomas]

We found that antitumor effect of OK-432, a lyophylized preparation of an attenuated strain of streptococcus pyogenes, on colorectal carcinoma was greatly augmented when it was injected intratumorally in conjunction with fibrinogen. Twenty cases of colorectal cancer received intratumoral injection of 5 KE of OK-432 mixed with 80mg of fibrinogen including factor-XIII and 1ml of aprotinin at the time of endoscopic examination. Changes in the shape of the tumors were observed endoscopically within a few days after injection, and in most cases, decrease in the height of tumor margin was noted. Histopathological findings on surgically resected specimens revealed that the fine meshwork of fibrin was formed at the injected site soon after the injection, and a marked infiltration of inflammatory cells including neutrophils, plasma cells, macrophages, eosinophils and lymphocytes. Such granulomatous changes developed over 7 days after injection, and the degradation of tumors were observed. By 14 days after the injection, tumor tissues were largely replaced with granulomas, and shrinkage of tissues were observed. These findings indicated that fibrinogen including factor-XIII and aprotinin has a potential ability to augment the immunoreaction induced by biological response modifiers, and intratumoral injection of OK-432 in conjunction with fibrinogen solution was superior to intratumoral injection of OK-432 alone as the local immunotherapy of colorectal cancer.     

Pathophysiology and treatment of multiple organ failure among hepatectomized cirrhotic patients

Our previous studies have claimed that cirrhotic rats, induced with CCl4, showed depressed reticuloendothelial system (RES) function and increased susceptibility to infection. We have also shown that OK-432, a non-specific immunopotentiator, and ATP-MgCl2, which improves depressed intracellular energy metabolism, improve RES function of cirrhotic rats and that thereby improve survival following peritonitis or hepatectomy. The present study was undertaken to investigate whether OK-432 or ATP-MgCl2 could be beneficial for the prevention of multiple organ failure (MOF) following hepatectomy among the cirrhotics. The cirrhotics with hepatocellular carcinoma, who underwent partial hepatectomy (segmentectomy or subsegmentectomy) were given OK-432 (5 KE/day for 4 days) preoperatively or ATP-MgCl2 (50 mumole/kg) within 24 hours following the operation. The rates of postoperative pulmonary complication and the operative mortality were compared among OK-432 group, ATP-MgCl2 group and controls. The rates of posthepatectomy pulmonary complication and operative mortality were decreased with these treatments compared to the controls. The RES function was also improved with these treatments. These data suggest that the cirrhotic patients are the immunocompromised hosts showing the depressed RES function and that the enhancement of RES function with OK-432 or ATP-MgCl2 is beneficial for the prevention of posthepatectomy MOF among cirrhotics.     

沙培林膀胱灌注对浅表性膀胱癌患者术后疗效观察

目的 研究沙堵林(OK-423)膀胱灌注预防浅表性膀胱癌术后的疗效及安全性.方法 将78例浅表型膀胱癌患者随机分成两组.沙培林组(40例)术后1周开始常规灌注沙培林5KE,膀胱内灌注保留2h,每周1次连续6周,之后每月1次连续8个月.对照组(38例)灌注吡柔比星30mg,灌注方法 同沙墙林组.结果随访6～36个月.原发...     

Complete remission of advanced renal cell carcinoma by chemotherapy and surgical treatment: a case report

A rare case of metastatic renal cell carcinoma which represented complete remission by chemotherapy and surgical treatment is presented. A 59-year-old female was admitted to our hospital because of general fatigue, weight loss and appetite loss. The diagnosis of right renal tumor metastasized to both lungs and extending into the inferior vena cava was made by radiographic findings. Because of very poor general condition the first choice of treatment was chemotherapy with cisdichlorodiamine platinum, adriamycin, cyclophosphamide, 1-(2-tetrahydrofuryl)-5-fluorouracil) (UFT), and OK432. Five months after the beginning of chemotherapy both lung coin lesions disappeared completely, and radical nephrectomy including venacavotomy and tumor thrombectomy was performed. At present, 6 months after the radical nephrectomy, she is free from the disease and complete remission has been obtained by oral administration of 400 mg/day UFT and 5.0 KE OK432 intracutaneous injection every week.     

Is intralesional injection of OK-432 effective in the treatment of lymphangioma in children?

BACKGROUND: Intralesional injection of OK-432 has been proposed as an effective treatment of lymphangioma. The aim of this study was to review our experience with OK-432 injection of lymphangioma and to identify factors associated with successful outcome. METHODS: We made a case note review of 19 children who received OK-432 injection. Median duration of follow-up was 17 months. RESULTS: Lesions were diagnosed antenatally in 4 children, at birth in 4 children, and between 1 month and 11 years in the remainder. Anatomic locations were head/neck in 14, axilla in 1, and multiple locations in 4. Median number of injections per child was 2 (range, 1 to 5). Disappearance of the lesion was achieved after OK-432 injection in 2 patients (11%) and a marked reduction in 5 (26%); all these lesions were in the head and neck. Lesions larger than 5 cm and those outside the head and neck region did not respond well to OK-432 injection. Fourteen children (74%) required surgical excision after injection. Complications of OK-432 injection included partial tracheal obstruction, fever, local inflammatory response, and abscess formation. CONCLUSIONS: OK-432 injection was effective in approximately one third of children with lymphangioma. Lesions outside the head and neck and those larger than 5 cm are unlikely to respond to this therapy. Injection of lymphangioma surrounding the airways may be hazardous.