Effect of Post-prandial Posture on Orocecal Transit Time and Digestion of Milk Lactose in Humans

We examined the effect of post-prandial body posture on orocecal transit time and absorption of milk lactose using the breath hydrogen test. In this experiment, subjects ingested a cup of commercially available milk to which we had added a small amount of lactosucrose (an indigestible trisaccharide), and then they lay on their backs or sat on a chair for the first 4 hr (from 08:00 to 12:00). After four hours lying or sitting, they remained sedentary on a sofa for the second six hr (from 12:00 to 18:00). Participants' end alveolar breath samples were collected every 15 min from 08:00 to 12:30, then every 30 min from 13:00 to 18:00. The experiment was conducted on two consecutive days using a randomized, crossover study design. Examination showed that the orocecal transit time of the oligosaccharides (lactosucrose and milk lactose) under the post-prandial supine condition was significantly longer than that under the sitting condition. In addition, the amount of breath hydrogen excretion under the supine condition was significantly lower than under the sitting condition, indicating that the unabsorbed milk lactose moved into cecum under the supine condition is smaller than that under the sitting condition. These findings provide evidence that postprandial supine posture works more beneficially to digest and absorb milk lactose when compared to the sitting posture.

Energy expenditure during walking with weight-bearing control (WBC) orthosis in thoracic level of paraplegic patients

STUDY DESIGN

Comparative study of the effectiveness of walking exercise with a newly developed gait orthosis, the weight-bearing control (WBC) orthosis, for thoracic level of paraplegic patients.

OBJECTIVES

To test its feasibility as a rehabilitation alternative for paraplegic patients, the energy consumption and cost during walking with WBC were calculated and compared with the values of conventional orthoses given in previous reports.

SETTING

National Rehabilitation Center for the Disabled, Japan.

METHODS

Four paraplegic patients with traumatic spinal cord injuries ranging from T8 to T12 participated. Experiments were conducted after 3 months of the orthotic gait training with WBC. The cardiorespiratory parameters were continuously measured at rest and during walking with a telemetric device. The steady-state value of the oxygen uptake (V(O2)), heart rate (HR), the energy consumption (J/kg/s) and energy cost (J/kg/m) were calculated.

RESULTS

The average walking speed was 19.0 +/- 2.58 m/min. The steady-state value of the V(O2) and HR were 16.08 +/- 1.93 ml/kg and 147.3 +/- 10.94 b/min, respectively. The energy cost during orthotic walking tended to be better than the values of conventional orthoses, whereas the energy consumption was almost similar.

CONCLUSION

WBC enables thoracic level of paraplegic patients to walk at relatively higher speed than conventional orthoses under similar energy expenditure. The special devices equipped with WBC are therefore considered to lead to improvement of the energy cost of walking. The physical intensity presumed by cardiorespiratory responses during walking with WBC is suited to promote their aerobic capacity. Therefore, it is concluded that the WBC orthosis could be an effective alternative in rehabilitation for thoracic level of paraplegic patients.

Effects of dim or bright-light exposure during the daytime on human gastrointestinal activity

On the basis of our previous findings that bright-light exposure during the daytime has profound influence on physiological parameters such as melatonin secretion and tympanic temperature in humans, we proposed the hypothesis that bright vs. dim light-exposure during the daytime has a different influence on the activity of the digestive system via the endocrine and/or autonomic nervous system. To examine this hypothesis, we conducted a series of counterbalanced experiments in which subjects stayed the daytime (7:00 to 15:00h) under either a dim (80 lux) or bright (5,000 lux) light condition. We measured gastrointestinal activity using a breath hydrogen (indicative of carbohydrate malabsorption) and an electrogastrography (EGG, indicative of gastric myoelectric activity) test. The results showed the postprandial breath hydrogen excretion during the following nighttime period after daytime exposure to the dim-light condition was significantly higher than under the bright-light condition (p < 0.05). In addition, the spectrum total power of the EGG recorded after taking the evening meal was significantly lower for the dim than bright-light condition (p < 0.05). These results support our hypothesis and indicate that dim-light exposure during the daytime suppresses the digestion of the evening meal, resulting in malabsorption of dietary carbohydrates in it.

Liver dysfunction among workers handling 5-nitro-o-toluidine

BACKGROUND

5-Nitro-o-toluidine is an aromatic nitro amino compound. While other aromatic compounds are known to damage the human liver and are registered as toxic substances, toxicity information concerning 5-nitro-o-toluidine is lacking.

AIMS

To investigate the hepatotoxicity of 5-nitro-o-toluidine.

PATIENTS AND METHODS

Of 15 workers in the same factory who handled 5-nitro-o-toluidine, three were hospitalised with symptoms of acute liver dysfunction. Suspecting a link between liver dysfunction and working conditions, we correlated workplace factors with clinical findings in all 15 workers.

RESULTS

Blood biochemistry tests indicated liver damage in seven of 15 study subjects. Workers who handled 5-nitro-o-toluidine and nitrosyl sulphuric acid often loosened their respiratory protective equipment shortly after 5-nitro-o-toluidine powder had been dispersed into the air of the room. No potential hepatotoxins were present except for 5-nitro-o-toluidine. Six of the affected workers had handled 5-nitro-o-toluidine 12 to 20 times; the seventh worker had handled the powder three times; and the other eight workers without liver dysfunction had handled the material once or twice. No other significant differences in background were evident between the affected and unaffected workers, such as age, sex, or protective measures. Histological findings during recovery from liver damage were similar to those of acute viral hepatitis. None of the 15 subjects has demonstrated liver damage since the factory was closed.

CONCLUSIONS

A link between liver dysfunction and 5-nitro-o-toluidine exposure is suggested by greater severity of liver dysfunction associated with more episodes of handling.

Effect of the dose and duration of interferon-alpha therapy on the incidence of hepatocellular carcinoma in noncirrhotic patients with a nonsustained response to interferon for chronic hepatitis C

OBJECTIVE

We evaluated the effect of dose and duration of treatment with interferon (IFN)-alpha on the incidence of hepatocellular carcinoma (HCC) after IFN treatment in patients with chronic hepatitis C.

METHODS

A total of 291 noncirrhotic patients with chronic hepatitis C without hepatitis B virus coinfection in whom hepatitis C virus (HCV) was not eradicated by IFN-alpha therapy were retrospectively analyzed. The incidence of HCC after IFN therapy was compared according to the total dose or duration of treatment.

RESULTS

Patients were followed up for 6-117 months after the end of IFN treatment. The duration of IFN treatment (< or =24 vs. >24 weeks) had no effect on the incidence of HCC. However, the incidence of HCC was significantly lower in patients who received >500 million units of IFN as a total dose than in patients who received < or =500 million units of IFN (p = 0.0480), and the total dose of IFN (>500 million units) was an independent factor affecting the incidence of HCC (p = 0.0405). In addition, when focusing on patients whose histology was F2 or F3 before IFN treatment, the suppressive effect of the total dose of IFN (>500 million units) was emphasized (p = 0.0049 in generalized Wilcoxon test and p = 0.0178 in multivariate analysis).

CONCLUSIONS

Patients with chronic hepatitis C should receive more than 500 million units of IFN when IFN is used to decrease the incidence of subsequent HCC.

Effect of postprandial posture on digestion and absorption of dietary carbohydrate

The effect of postprandial body posture on digestion and absorption of dietary carbohydrate were examined through breath hydrogen test on 6 female subjects. During the experiment, the participants either sat on a chair or lay on their backs for the first 4 hr (from 08:00 to 12:00) after eating the test breakfast meal. They then remained sedentary on a sofa for 6 hr (12:00 to 18:00). Participants' end alveolar breath samples were collected for 10 hr (every 15 min from 08:00 to 12:30, and then every 30 min until 18:00). The experiment was conducted on two consecutive days using a randomized, crossover study design. The results demonstrated that in the supine position orocecal transit time of the test meal was significantly slower than in the sitting position (260 +/- 21 min and 238 +/- 20 min, respectively, p < 0.01). In addition, afternoon breath hydrogen excretion due to a partial malabsorption of dietary carbohydrate and its fermentation in the colon was significantly larger in the sitting position (144.0 +/- 24.1 ppm.hr) than in the supine position (110.0 +/- 26.1 ppm.hr, p < 0.05). These results support the hypothesis that there was a marked effect of postprandial body posture on the function of the digestive system. The present findings suggest that the postprandial supine position is preferable to the sitting position for the digestion and absorption of dietary carbohydrate.

[A new development in interventional radiology for hepatocellular carcinoma]

In Japan, interventional radiology (IVR) treatments such as transcatheter arterial embolization (TAE), percutaneous ethanol injection therapy (PEIT), and intraarterial infusion chemotherapy play an important role in the treatment of hepatocellular carcinoma because of the associated cirrhosis (impairment of liver function) and occasional multicentricity. With progress in catheters, embolic materials, and imaging equipment such as the so-called "IVR-CT", superselective TAE and precise evaluation of tumor lesions has become feasible. However, the impact of TAE on survival in patients with hepatocellular carcinoma remains to be determined because no survival benefit was seen in four of five randomized controlled trials (RCTs) in Europe and Eastern countries, in which TAE was compared with no treatment (3 trials), i.v. 5-fluorouracil (1 trial), or tamoxifen (1 trial). To resolve questions arising from these results, a fair number of trials, particularly RCTs are needed in Japan.

Effect of skin pressure by clothing on small bowel transit time

We examined the effect of increased skin pressure from tight clothing on small bowel transit time by means of the breath hydrogen test, using milk that contained lactulose as an additional indigestible disaccharide, which is used as a test meal after overnight fasting. In this experiment, we measured the small bowel transit time from 9 healthy and non-constipated female subjects with two different skin pressures that were applied by loose-fitting experimental garment or an additional tight-fitting girdle on two consecutive days. The skin pressure of the latter condition was 8-9 mmHg higher than that of the former one on the participants' waist, abdomen and hip region. The experimental order of the two skin pressure conditions was counterbalanced. As a result, the small bowel transit time obtained with and without girdle did not differ significantly (165.0 +/- 26.0 minutes for less skin pressure condition and 173.3 +/- 26.8 minutes for more skin pressure condition, n = 9, p = 0.43). This result indicated that the skin pressure from clothing has no effect on the passage rate of food through the small intestine.

Bullectomy is beneficial in the pulmonary blood flow/driving pressure relationship in bullous emphysema patients

OBJECTIVES

Few physiological studies have been on pulmonary circulation, including the relationship between pulmonary blood flow and driving pressure, and viscosity changes arising from hematocrit changes before versus after lung volume reduction Surgery or bullectomy in emphysematous patients.

METHODS

We studied the relationship between pulmonary blood flow and driving pressure before and after bullectomy using a unilateral pulmonary artery occlusion test based on pulmonary blood flow fractions obtained by pulmonary blood flow scintigraphy in 7 patients with pulmonary emphysema associated with bullae.

RESULTS

Among the 7 undergoing bullectomy, the pulmonary blood flow/driving pressure relationship decreased in 5 and was unchanged in 2. Of the 11 lungs treated by bullectomy, this relationship decreased in 8 lungs, but not 3 (p < 0.01). No significant difference was seen in oxygen partial pressure in arterial and mixed venous blood or hematocrit.

CONCLUSION

We concluded that bullectomy shifted the pulmonary blood flow/driving pressure relationship downword in some cases with significant bullae.

Impact of diabetes mellitus on the prognosis of patients with hepatocellular carcinoma

BACKGROUND

The majority of patients with hepatocellular carcinoma (HCC) have coexisting cirrhosis or chronic hepatitis, often complicated by diabetes mellitus. In the current study, the authors evaluated the impact of diabetes mellitus on the prognosis of patients with HCC.

METHODS

Among 581 patients with HCC who had been diagnosed and treated between 1990 and 1999, survival was compared between those patients with and those patients without diabetes mellitus. The rate of disease recurrence after treatment also was analyzed.

RESULTS

Ninety-two patients (15.8%) had diabetes mellitus. There was no significant difference with regard to patient characteristics (i.e., age, gender, or alcohol intake) or liver function between those patients with and those patients without diabetes mellitus. No differences were observed in survival between patients with diabetes mellitus and patients without it. Among the 195 patients with a solitary HCC lesion measuring < or = 3 cm in greatest dimension, the survival of the 32 patients with diabetes mellitus was significantly poorer than that of the 163 patients without diabetes mellitus (P = 0.0273), despite no apparent difference in liver function between the 2 groups. On multivariate analysis, diabetes mellitus was found to be an independent factor predicting lower survival after treatment (P = 0.0077) among patients with a solitary HCC lesion measuring < or = 3 cm in greatest dimension. No difference in the rate of recurrence was observed between the two groups in all the patients and in those patients with a solitary HCC lesion measuring < or = 3 cm in greatest dimension.

CONCLUSION

The results of the current study indicated that the presence of diabetes mellitus worsens the prognosis of patients with a solitary HCC lesion measuring < or = 3 cm in greatest dimension; it appears to impact prognosis in patients with HCC when HCC is treatable, based on the size and the number of lesions. However, diabetes mellitus did not appear to affect the prognosis in the general population of patients with HCC. Based on the current study data, diabetes mellitus does not appear to modify the progression of HCC and its recurrence after treatment, but it does appear to worsen the prognosis of patients with HCC by means of a rapid decline in remnant liver function caused by repeated treatment of HCC.

Characteristics and course of small hepatocellular carcinomas in patients with hepatitis C virus types 1 and 2

The associations between types of HCV and tumor characteristics and recurrence and survival after treatment of small HCC were investigated. Viral genotype-specific antibodies were measured in sera obtained at the time of diagnosis of HCC, in 92 patients with HCC < or = 2 cm in diameter who were treated between 1990 and 1998. The degrees of tumor differentiation and angiographically-evaluated hypervascularity were compared between patients infected with HCV type 1 and those with type 2. Survival, time to recurrence, and patterns of recurrence after initial treatment also were compared. On pathologic evaluation, 6 of 21 HCC (28.6%) in patients with HCV type 2 were well-differentiated, whereas 28 of 48 HCC (58.3%) in patients with HCV type 1 were well-differentiated (P = 0.0229). HCC in patients with HCV type 2 showed hypervascularity more frequently than HCC in patients with HCV type 1, with tumor staining evident by digital subtraction arteriography in 17 of 22 patients with HCV type 2 (77.3%) vs. 20 of 50 in patients with HCV type 1 (40.0%, P = 0.0036). Survival and overall recurrence rates were similar in patients infected with HCV type 1 and with HCV type 2 (P = 0.5537). In the analyses of patterns of recurrence, recurrences in patients infected with HCV type 2 were relatively more likely to be intrahepatic metastases (P = 0.0342), that was closely related to the differentiation of HCC. Multicentric occurrence of HCC was a more frequent type of recurrence in patients with HCV type 1 (P = 0.1619), and infection of HCV type 1 was an independent factor for multicentric occurrence in multivariate analysis (P = 0.0021). In HCC < or = 2 cm in diameter, HCV type 2 is associated with more progression of HCC than HCV type 1, whereas patients with HCV type 1 may be at higher risk for multicentric HCC occurrence after the treatment of HCC.

Everyday breath hydrogen excretion profile in Japanese young female students

A breath hydrogen test has been used widely as a noninvasive and simple method of detecting carbohydrate malabsorption as well as estimation of the small intestinal and orocecal transit time. By means of this method, we have examined the change in breath hydrogen concentration of young female students in their everyday life in order to reveal the breath hydrogen excretion profile under normal circumstances. In this survey, we have asked them to collect their own breath samples every one-hour as regularly as possible during one day from awakening until bedtime. We also asked them to complete the questionnaire concerning their dietary habit, dietary record and physical activities. Among the 43 subjects who gave the breath hydrogen records, 37 subjects excreted detectable hydrogen into their alveolar air. By comparing the changes in breath hydrogen concentration during the time of day, breath hydrogen excretions could be classified into two distinct patterns; more than half of the total hydrogen excretion occurred in the first half of the waking hours (designated as "pattern A", 18 cases) and in the latter half (designated as "pattern B", 19 cases). Taking into consideration the subjects' records of diets and physical activities, the early-pronounced breath hydrogen excretion observed among 18 "pattern A" students was probably resulted from the malabsorption of the dietary carbohydrate in the breakfast meals.

[A case of aneurysm of the ductus arteriosus in the adult]

Aneurysm of the ductus arteriosus in the adults is rare. A 60-year-old male with no symptoms was admitted to our hospital. 3 D-CT scans and aortograms indicated a diagnosis of aneurysm of the ductus arteriosus. Operation was done through median sternotomy with the aid of partial cardiopulmonary bypass. The saccular aneurysm was located between the aortic isthmus and the left pulmonary artery. The aneurysm was resected and closed a patch. The post-operative course was uneventful.

Effects of skin pressure by clothing on digestion and orocecal transit time of food

In order to reveal the influence of clothing skin pressure on digestion of food through the gastrointestinal tract, we examined the absorption of dietary carbohydrate and orocecal transit time of a test meal by means of a breath hydrogen test on 7 healthy young women. In this experiment, we collected breath samples from the participants wearing loose-fitting experimental garment on the second day of the experiment and from the same participants but wearing an additional tight-fitting girdle on the following day for 16 hours and 9 hours, respectively. Skin pressure applied by a girdle on participant's waist, abdomen and hip region was 15.5 +/- 0.4 mmHg (mean +/- SE), 11.0 +/- 0.2 mmHg, and 13.6 +/- 0.6 mmHg, respectively, and the values were 2-3 times larger than those of the experimental garment. The hydrogen concentration vs. time curve showed that breath hydrogen levels at its peaks (15:00, 15:30, 16:00, 16:30, and 17:00 hr) on the third day of the experiment were significantly higher than those of the corresponding time on the second day (p < 0.05 at 17:00 and 15:00, p < 0.01 at 15:00, 16:00 and 16:30). Consequently, significantly pronounced breath hydrogen excretion was observed under the "pressure" clothing condition (p < 0.01). On the other hand, the transit time of the test meal for the subjects wearing a girdle did not differ significantly from that for the subjects wearing the garment of less pressure (270 +/- 18 minutes and 263 +/- 21 minutes, respectively). These results indicate that the clothing skin pressure has an inhibitory effect on the absorption of dietary carbohydrate in the small intestine, but no effect on the orocecal transit time of a meal.

Characterization of cross-links between cellulose microfibrils, and their occurrence during elongation growth in pea epicotyl

The occurrence and chemical nature of the cross-links between cellulose microfibrils in outer epidermal cell walls in Pisum sativum cv. Alaska was investigated by rapid-freezing and deep-etching techniques coupled with chemical and enzymatic treatments. The cell wall in the elongating region of epidermal cells was characterized by the absence of the cross-links, while in the elongated region, the cell wall was characterized by the presence of cross-links. The cross-links remained in the cell wall of the elongated region after treatment with SDS electrophoresis sample buffer and treatment with 4% potassium hydroxide. After treatment with endo-1,4-beta-glucanase, which fragments xyloglucan, the cross-links were remarkably reduced from the cell wall of the elongated region. The endoglucanase treatment also reduced immunogold labeling of xyloglucan in the cell wall. The endoglucanase hydrolysate from the cell wall fraction of the elongated region gave spots of oligosaccharides in thin layer chromatography, which were identical to the spots of xyloglucan oligosaccharides produced by xyloglucanase from both the cell wall fraction and tamarind xyloglucan. These results indicate that the cross-links are made of xyloglucan. We discussed the possibility of cross-links involved in the control of mechanical properties of the cell wall.

The effect of retreatment with interferon-alpha on the incidence of hepatocellular carcinoma in patients with chronic hepatitis C

BACKGROUND

Interferon (IFN) has been reported to have beneficial long term effects that reduce the occurrence of hepatocellular carcinoma (HCC), even in patients who do not have complete responses to IFN. The authors evaluated the effect of retreatment with IFN-alpha on the long term prognoses of those with incomplete responses to their initial IFN-alpha treatment.

METHODS

Among 271 patients with incomplete responses to initial IFN-alpha treatment who had received sufficient dose and duration (a total dose of more than 350 megaunits administered over a period longer than 12 weeks) between October 1989 and September 1997, 63 patients received retreatment and 208 did not. The authors retrospectively compared the incidence of HCC between patients who received retreatment and those who did not.

RESULTS

There were no significant differences in the clinical characteristics between these two groups. The cumulative incidence of HCC was significantly lower among the patients who had retreatment, and retreatment with IFN-alpha was the only factor that correlated with the lower incidence of HCC in multivariate analysis. The results were similar when the 12 patients with complete responses to retreatment were excluded from the analysis.

CONCLUSIONS

Retreatment with IFN-alpha appeared to have the additional effect of suppressing the development of HCC in patients who had incomplete responses to the initial treatment, even when the hepatitis C virus was not cleared (i.e., a complete response was not achieved) with retreatment. Further prospective study is required.

The effect of retreatment with interferon-alpha on the incidence of hepatocellular carcinoma in patients with chronic hepatitis C

BACKGROUND

Interferon (IFN) has been reported to have beneficial long term effects that reduce the occurrence of hepatocellular carcinoma (HCC), even in patients who do not have complete responses to IFN. The authors evaluated the effect of retreatment with IFN-alpha on the long term prognoses of those with incomplete responses to their initial IFN-alpha treatment.

METHODS

Among 271 patients with incomplete responses to initial IFN-alpha treatment who had received sufficient dose and duration (a total dose of more than 350 megaunits administered over a period longer than 12 weeks) between October 1989 and September 1997, 63 patients received retreatment and 208 did not. The authors retrospectively compared the incidence of HCC between patients who received retreatment and those who did not.

RESULTS

There were no significant differences in the clinical characteristics between these two groups. The cumulative incidence of HCC was significantly lower among the patients who had retreatment, and retreatment with IFN-alpha was the only factor that correlated with the lower incidence of HCC in multivariate analysis. The results were similar when the 12 patients with complete responses to retreatment were excluded from the analysis.

CONCLUSIONS

Retreatment with IFN-alpha appeared to have the additional effect of suppressing the development of HCC in patients who had incomplete responses to the initial treatment, even when the hepatitis C virus was not cleared (i.e., a complete response was not achieved) with retreatment. Further prospective study is required.

Combined thoracic aortic or upper digestive tract resection for lung cancer and malignant mediastinal tumor

OBJECTIVE

We studied possible indications and combined resection in patients with lung cancer and mediastinal tumors requiring combined thoracic aortic or upper digestive tract resection.

METHODS

Ten patients with lung cancer and malignant mediastinal tumors (9 men and 1 woman aged 39 to 72 years; mean: 60.5) underwent combined aortic or upper digestive tract resection.

RESULTS

Five--3 [corrected] with primary lung cancer, 1 with thymic cancer, and 1 with liposarcoma--, underwent combined aortic resection. In 2 each, lung cancer and malignant mediastinal tumor had infiltrated the thoracic aorta. The remaining case of lung cancer was complicated by aortic aneurysm in the distal arch. Cardiopulmonary bypass was conducted in 4, and selective cerebral perfusion in 2. Three patients are alive after 11, 22, and 61 months without disease recurrence. Those undergoing combined upper digestive tract resection all had lung cancer, with 4 having tumors infiltrating the esophagus or corpus ventriculi. The remaining patient had both lung and esophageal cancer. The patient treated with combined corpus ventriculi resection has survived 24 months and the patient treated with combined esophageal resection has survived 12 months without disease recurrence. The 1-year survival rate was 60%, 2-year 23%, and 3-year 23%. Prognosis was generally poor with the longest survival 13 months with N2 lung cancer.

CONCLUSIONS

In combined resection due to malignant mediastinal tumor, T4N0-1 lung cancer, or diseases such as aortic aneurysm, prognosis can be expected to improve. Despite the often poor prognosis in T4N2 lung cancer, surgical intervention may be indicated to avoid complications due to tumor invasion and to lengthen survival and improve quality of life.

Risk factors for lung cancer among Northern Thai women: epidemiological, nutritional, serological, and bacteriological surveys of residents in high- and low-incidence areas

Lung cancer incidence among Northern Thai women is one of the highest in Asia (an annual age-adjusted incidence rate of 37.4 per 100,000), and the incidence rate significantly differs by geographical districts. Therefore, we conducted a comparative study of women living in the Sarapee area, which showed the highest (crude incidence rate, 40.9), and the Chom Tong area, which had one of the lowest incidence rates (8.5) in Chiang Mai Province, despite the two areas' geographical and cultural closeness. The women in this study were either family members of lung cancer patients or their neighbors. To find clues to the etiology of lung cancer, this study used various epidemiological and biochemical approaches: interviewing on lifestyle factors, duplicate meals, chemical examination of drinking water, biochemical analysis of sera, mutagenicity test of urine, and monitoring of fungi and bacteria in the living environment. We found that tobacco smoking (Khiyo, local cigars) was less frequently observed in Sarapee (high incidence), compared with Chom Tong (low incidence), and that the history of chronic benign respiratory diseases was the most distinct event among women in Sarapee, resulting in a significantly increased percentage of those with a history of both benign respiratory diseases and tobacco smoking. This population revealed increased levels of serum tumor necrosis factor (TNF)-alpha, an endogenous tumor promoter. Furthermore, significantly increased urine mutagenicity was found to be closely associated with history of benign respiratory disease in Sarapee. The fungus which was most commonly found in the air inside houses in Sarapee was identified as Microsporum canis. Additionally, significantly increased serum concentrations of a constituent of the fungus were found in Sarapee women, compared with those in Chom Tong. Our results suggest that tobacco (Khiyo) smoking alone may not be able to explain the very high incidence of female lung cancer in Northern Thailand, and that chronic benign respiratory disease, possibly caused by the infection of fungi such as M. canis, is likely to be involved in the etiology of female lung cancer in North Thailand.