Acinar flow irreversibility caused by perturbations in reversible alveolar wall motion

Mixing associated with "stretch-and-fold" convective flow patterns has recently been demonstrated to play a potentially important role in aerosol transport and deposition deep in the lung (J. P. Butler and A. Tsuda. J. Appl. Physiol. 83: 800-809, 1997), but the origin of this potent mechanism is not well characterized. In this study we hypothesized that even a small degree of asynchrony in otherwise reversible alveolar wall motion is sufficient to cause flow irreversibility and stretch-and-fold convective mixing. We tested this hypothesis using a large-scale acinar model consisting of a T-shaped junction of three short, straight, square ducts. The model was filled with silicone oil, and alveolar wall motion was simulated by pistons in two of the ducts. The pistons were driven to generate a low-Reynolds-number cyclic flow with a small amount of asynchrony in boundary motion adjusted to match the degree of geometric (as distinguished from pressure-volume) hysteresis found in rabbit lungs (H. Miki, J. P. Butler, R. A. Rogers, and J. Lehr. J. Appl. Physiol. 75: 1630-1636, 1993). Tracer dye was introduced into the system, and its motion was monitored. The results showed that even a slight asynchrony in boundary motion leads to flow irreversibility with complicated swirling tracer patterns. Importantly, the kinematic irreversibility resulted in stretching of the tracer with narrowing of the separation between adjacent tracer lines, and when the cycle-by-cycle narrowing of lateral distance reached the slowly growing diffusion distance of the tracer, mixing abruptly took place. This coupling of evolving convective flow patterns with diffusion is the essence of the stretch-and-fold mechanism. We conclude that even a small degree of boundary asynchrony can give rise to stretch-and-fold convective mixing, thereby leading to transport and deposition of fine and ultrafine aerosol particles deep in the lung.

Curative laparoscopic surgery for early gastric cancer: five years experience

Sixty-one patients who were diagnosed with mucosal gastric cancer have been successfully treated with two laparoscopic techniques at our institute from March 1992 to March 1997. One is laparoscopic wedge resection of the stomach using a lesion-lifting method for lesions of the anterior wall, the lesser curvature, and the greater curvature of the stomach. The other is laparoscopic intragastric mucosal resection for lesions of the posterior wall of the stomach and near the cardia or the pylorus. Indications are as follows: (1) preoperatively diagnosed mucosal cancer; (2) <25 mm diameter elevated lesions; and (3) <15 mm diameter depressed lesions without ulcer formation. Patients were discharged in 4 to 8 days uneventfully. There was no major complication or mortality. The resected specimens had sufficient surgical margins horizontally (16 +/- 5 and 8 +/- 4 mm, respectively) and vertically. In one patient histologic examination revealed slight tumor infiltration into the submucosal layer with lymphatic invasion. He underwent gastrectomy with lymph node dissection 1 month after surgery. Otherwise, histologic examination revealed curative surgery. All patients in the series have survived during the 4- to 65-month follow-up period. There have been two recurrences in the series, both of which were found near the staple line 2 years after the initial surgery and were still mucosal lesions. They were successfully treated by open gastrectomy and laser irradiation. A separate early gastric cancer was found 2 years after the initial surgery in one patient, who then underwent curative open gastrectomy. In conclusion, if the patients are selected properly, these laparoscopic procedures are curative, minimally invasive treatment for early gastric cancer.

Preventive effect of matrix metalloproteinase inhibitor, R-94138, in combination with mitomycin C or cisplatin on peritoneal dissemination of human gastric cancer cell line TMK-1 in nude mice

R-94138, a matrix metalloproteinase inhibitor, was examined for the ability to prevent peritoneal dissemination of a human gastric cancer xenograft, TMK-1. When the supernatant of a co-culture of TMK-1 cells and human normal fibroblast cells was subjected to gelatin zymography, it was clear that the protein expression of MMP-2 had been inhibited by R-94138. When TMK-1 was injected intraperitoneally (i.p.) into nude mice at 5 x 10(5) cells/body, the resulting peritoneal dissemination mimicked clinical carcinomatous peritonitis. When the maximum tolerated dose of mitomycin C (MMC) or cisplatin (DDP) was given 12 h after the tumor inoculation, peritoneal dissemination was completely inhibited, while the effect of R-94138 was limited when it was given i.p. at a dose of 20 mg/kg in a schedule of q.d. x 5 starting 12 h after tumor injection. MMC and DDP also suppressed peritoneal dissemination when they were administered 1 week after the tumor inoculation at a single dose of 2 and 3 mg/kg i.p., respectively. R-94138 inhibited peritoneal dissemination when it was administered i.p. at a dose of 30 mg/kg in a schedule of q.d. x 5 starting from 1 week after tumor injection. The combination of MMC and R-94138 increased the preventive effect on peritoneal dissemination. R-94138 seems to be a promising candidate to prevent peritoneal dissemination of gastric cancer.

Management of primary gastric lymphomas from a surgeon's viewpoint

Primary gastric lymphoma is a relatively uncommon disease and controversy still exists over its management. In order to assess prognostic factors of lymphomas, we carried out a retrospective study of 28 surgically treated gastric lymphoma patients. The overall survival rate for all the patients in the study was 33% at 10 years. On univariate analysis, lymph node metastasis and depth of tumor infiltration proved to be a significant prognostic factor while size and location of tumor, sex, and method of resection was not. From our results we believe that gastric lymphoma can be regarded as a localized disease in the early stages and a curative resection can be attained when aggressive surgery is possible.

Combined antitumour activity of mitomycin C, 5-fluorouracil and interleukin-2 against human colon cancer cells

Combined treatment of interleukin-2 (IL-2), 5-fluorouracil (5-FU) and mitomycin C (MMC) is reported to be effective against hepatic metastasis of colon carcinoma. To clarify this modality, we investigated lymphokine activated killer (LAK) activity of human peripheral lymphocytes on colon cancer cell lines by 51Cr release assay. LAK activity against Colo 205 cells by untreated lymphocytes was 12%, which increased to 25% upon the addition of 5-FU, but remained unchanged upon the addition of MMC. The combined antitumour activity of MMC or 5-FU with or without LAK-supernatant was evaluated by MTT assay; antitumour activity of MMC was increased by the addition of LAK-supernatant. The concentration of interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) was increased in LAK-supernatant, and the antitumour activity of combined IFN-gamma and MMC was synergistic. The mechanism of this therapy seemed to be associated with both increased LAK activity by 5-FU and increased antitumour activity of MMC with IFN-gamma.

Characteristics of Helicobacter pylori strains isolated from patients with different gastric diseases

The pathogenesis of chronic gastritis, gastric ulcer, duodenal ulcer, gastric cancer, and remnant gastritis is considered to be related to infection by Helicobacter pylori. The purpose of this study was to investigate the characteristics of H. pylori strains isolated from patients with various gastric diseases. Fifty strains of H. pylori were clinically isolated at Keio University Hospital and were assessed for (i) vacuolating cytotoxin (VT) production, by cytotoxic assay using rabbit kidney (RK) 13 cells; (ii) the expression of cytotoxin associated gene (cagA), by polymerase chain reaction; and (iii) motility on a semi-solid plate. Positivity for VT production by H. pylori strains isolated from patients with chronic gastritis, gastric ulcer, duodenal ulcer, gastric cancer, and remnant gastritis, was 100%, 89%, 92%, 100%, and 60%, respectively. There was no significant difference in the incidence of positivity for cagA among the strains isolated from different gastric diseases. Swarming distances, which indicate motility of H. pylori strains, were 12.7, 13.2, 12.8, 16.6 and 9.2mm in strains from chronic gastritis, gastric ulcer, duodenal ulcer, gastric cancer, and remnant gastritis, respectively, with H. pylori isolated from remnant gastritis showing significantly less motility than H. pylori isolates from other diseases. There were no significant differences in VT production and cagA positivity among the H. pylori strains.

Effect of additives on gelation and tissue adhesion of gelatin-poly(L-glutamic acid) mixture

Gelation and tissue adhesion of mixtures of gelatin and poly (L-glutamic acid) (PLGA) aqueous solution were investigated in the presence of additives following the addition of a water-soluble carbodiimide (WSC) that induced chemical cross linking between gelatin and PLGA. To prevent spontaneous gelation of the mixed solution through physical cross linking between gelatin molecules at room temperature, additives were added to the mixed solution. Among the additives studied, starch and urea were effective in preventing the spontaneous physical gelation. The mixed gelatin and PLGA solution set to a cross-linked hydrogel within scores of second by WSC addition, irrespective of the presence of urea, whereas the viscosity of the solution with added starch was too high to measure the gelation time. The cross-linked gelatin-PLGA hydrogels with and without urea showed higher bonding strength to soft tissues than fibrin glue. This was in marked contrast to gelatin-PLGA hydrogels with soluble starch. Irrespective of the presence of urea, the gelatin-PLGA hydrogels gradually biodegraded in the back subcutis of mice over 3 months and no severe inflammatory response to the hydrogels was observed. These findings indicate that urea is promising as an additive to prevent spontaneous physical gelation of the mixed gelatin and PLGA aqueous solution without changing the characteristics of WSC-induced cross linking and tissue adhesion of the formed hydrogel.

[A clinical study on the cases of ischemic colitis: comparison of clinical images based on time from onset of the disease to detection of bloody stool]

A study was performed on 28 cases of ischemic colitis. The patients were divided into three groups: Group A (9 cases with bloody stool detected within 2 hours after the onset of abdominal pain), Group B (7 cases with bloody stool detected in 2 to 6 hours), and Group C (12 cases with bloody stool detected after more than 6 hours). These cases were comparatively studied. Variables used were as follows: (1) age, (2) sex, (3) constipation, (4) vomiting, (5) peak value of WBC count (/microliter) after admission, (6) peak value of log CRP (microgram/dl), (7) presence of ulcerative lesion in endoscopic findings in acute stage. Using Group A B and C as classification variables, canonical discriminant analysis was performed. As a result, clear linearity was recognized in Group A-->B-->C, and the values (5), (6) and (7) were extracted as the corresponding variables. For these variables, significant difference was also noted in multivariate analysis of covariance. These results suggest that it is possible to predict the severity of the disease to some extent as represented by objective markers of inflammation by finding the time from onset of abdominal pain to detection of bloody stool.

Hemostatic capability of rapidly curable glues from gelatin, poly(L-glutamic acid), and carbodiimide

The hemostatic capability of rapidly curable glues composed of gelatin and poly(L-glutamic acid) (PLGA) was compared with that of the conventional fibrin glue. The hydrogels produced from mixed gelatin and PLGA aqueous solution within several seconds by addition of water-soluble carbodiimide (WSC) was applied to the dog spleen injured by needle pricking. The WSC-catalyzed gelatin-PLGA glues exhibited higher hemostatic capability than the fibrin glue. The total amount of bleeding from the injured spleen until hemostasis when the gelatin-PLGA hydrogel glues were applied was significantly smaller than that of the fibrin glue application. The gelatin-PLGA glue application enhanced the success rate of complete hemostasis to a significantly greater extent than the fibrin glue, while the frequency of glue applications until achieving complete hemostasis decreased. The gelatin PLGA hydrogels strongly adhered to the surface of dog spleen, whereas the fibrin hydrogel was easily detached from the spleen surface. It was concluded that this strong adhesion mechanically suppressed the bleeding, leading to enhanced hemostasis by the rapidly curable gelatin-PLGA glues.

Selective antitumor activity of MKT-077, a delocalized lipophilic cation, on normal cells and cancer cells in vitro

BACKGROUND AND OBJECTIVES

1-Ethyl-2-¿[3-ethyl-5-(3-methylbenzothiazolin-2-yliden)]-4-+ ++oxothiazolidin-2-ylidenemethyl¿pyridium chloride (MKT-077, formerly known as FJ776), a delocalized lipophilic cation, is known to accumulate in the mitochondria, according to the negative potential inside the mitochondria, and exert its cytotoxicity.

METHODS

The single-cell suspensions of human cancer cell lines, human spleen cells, and fresh cancer specimens obtained from patients with gastric carcinoma were used for the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay.

RESULTS

The antitumor activity of MKT-077 was dose and concentration related, and 50% inhibitory concentrations (IC50) ranged from 1.7 to 14.3 microg/ml, with a mean +/- standard deviation (SD) of 8.4 +/- 4.6 microg/ml. The IC50 of fresh surgical spleen-cell specimens ranged from 0.34 microg/ml to >100 microg/ml in a 48 h incubation, with a mean +/- SD of 66.5 +/- 37.7 microg/ml. When the antitumor activity of MKT-077 was compared between gastric cancer cells and spleen cells obtained from the same patient, the concentration-dependent antitumor activity of this agent was obvious in the cancer cells, while no significant cytotoxicity was observed in the spleen cells. The fresh surgical specimens of gastric cancer showed higher sensitivity to MKT-077 than did spleen cells at a concentration of 30 microg/ml, with a statistically significant difference at P < 0.05.

CONCLUSIONS

The selective antitumor activity of MKT-077 was confirmed using fresh surgical specimens and warrants further investigation.

Rebamipide attenuates gastric microcirculatory disturbances in the early period after thermal injury in rats

In our previous study we showed that rebamipide attenuated gastric erosions and active oxygen species released only from the gastric mucosa and not from circulating leukocytes after thermal injury. This study was designed to examine whether rebamipide affects the potential of active oxygen generation from circulating leukocytes, and attenuates microcirculatory disturbance caused by thermal injury to skin. Rats were anesthetized and a 30% full skin-thickness dorsal burn was inflicted. Microvascular images and leukocytes were observed using in vivo microscopy. Endothelial damage was assessed by monastral blue B deposits. Active oxygen species were measured by the chemiluminescence method. Rebamipide (100 mg/kg) decreased leukocyte rolling and monastral blue B deposits in venules but did not improve arteriolar contractions 15 min after thermal injury. These results suggest that rebamipide preserves gastric microcirculation possibly through inhibition of leukocyte adhesion and endothelial damage caused by thermal injury to skin.

Trends of average intake of macronutrients in 47 prefectures of Japan from 1975 to 1994--possible factors that may bias the trend data

To describe the geographical patterns and trends of macronutrient intake in Japan for the recent 20 years, we analyzed the data sets of the National Nutrition Surveys (J-NNS). First, we calculated regression coefficients for survey year by prefecture for energy, protein, fat, and carbohydrate intake. These results, however, could be affected by the changes in age and sex distributions of the survey samples. Secondly, as the food consumption data were based on household as a unit, we used proportions of the subjects who belong to age-specific groups and female subjects in a sub-sample for each prefecture in a given year for adjustment by general lineal model. As a result, 1% increase in the subjects aged 1-4, 10-19 and 65- years and female subjects was equivalent to the changes in average energy intake by -5.88, +2.27, -1.45 and -1.62 kcal, respectively. After the adjustment for age and sex, number of significant negative coefficients among 47 prefectures decreased for energy and carbohydrate intake, and that of positive coefficients increased for fat intake. This suggested that unadjusted trend data might lead to an overestimation of decreasing trends of energy and carbohydrate intake, and an underestimation of increasing trend of fat intake in the recent 20 years.

Antitumor activity of murine monoclonal antibody NCC-ST-421 on human cancer cells by inducing apoptosis

BACKGROUND

The murine monoclonal antibody NCC-ST-421 (ST-421) recognizes dimeric Le(a) antigen expressed on gastrointestinal cancer cells.

MATERIALS AND METHODS

Direct antitumour activity of ST-421 was evaluated using dimeric Le(a) positive cell lines Colo 205, Colo 201, HT-29 and WiDr; and negative cell lines MX-1 and K562.

RESULTS

While time- and concentration-dependent antitumour activity was observed against Colo 205 and Colo 201, no antitumour activity was detected against the other cell lines tested in an in vitro cytotoxicity assay. When ST-421 was administered intraperitoneally daily for 2 weeks to severe combined immunodeficient (SCID) mice transplanted with tumour xenografts, inhibition of tumour growth was observed against Colo 205, and to a lesser extent HT-29 and WiDr. Anti-asialo GM1 antibody did not block this antitumour activity, suggesting ST-421 has a direct cytotoxic effect. The degree of antitumour activity of ST-421 dependent on the grade of Le(a)-expression as detected by immunohistochemical staining.

CONCLUSIONS

Flow cytometric and immunohistochemical analysis suggests the induction of apoptosis may play a key role in the direct antitumour activity of ST-421 on Colo 205 cells.

Lymph node metastasis of early gastric cancer with submucosal invasion

BACKGROUND

A clinicopathological study of early gastric cancer with submucosal invasion was carried out in relation to lymph node metastasis.

METHODS

A retrospective study was conducted of 245 patients with submucosal gastric cancer treated by gastrectomy combined with D2 lymph node resection between 1985 and 1994 in a university hospital.

RESULTS

Lymph node metastasis was observed in 34 patients (14 per cent). The mortality rate due to recurrence in patients with lymph node metastasis (three of 34) was significantly higher than in those without lymph node metastasis (five (2 per cent) of 211) (chi2 = 3.95, 1 d.f., P < 0.05). Tumour size, depth of invasion, lymphatic involvement of cancer cells and preoperative diagnosis of advanced cancer correlated significantly with the presence of lymph node metastasis. When the submucosal carcinomas were classified into three categories according to depth of invasion by dividing the submucosal (sm) layer into three equal parts, sm1, sm2 and sm3, the incidence of lymph node metastasis increased from 2 per cent to 12 and 20 per cent respectively.

CONCLUSION

When the pathological report reveals sm1 invasion after laparoscopic or endoscopic surgery, reoperation should not be necessary because sm1-carcinomas with diameters of less than 2 cm do not usually metastasize to the lymph nodes.

[Recent progress of matrix metalloproteinase (MMP) research and its clinical application for cancer therapy]

The matrix metalloproteinases (MMPs) are a family of secreted and membrane-bound zinc-endopeptidases. These enzymes are capable of degrading the extracellular matrix, including collagens, laminin, proteoglycan and fibronectin. In some human cancers, a positive correlation has been demonstrated between MMP expression and the likelihood of developing metastasis. An imbalance between MMPs and the tissues inhibitor of metalloproteinases (TIMPs) may play a significant role in the invasive phenotype of cancers. Although TIMPs have been shown to inhibit tumor metastasis in some in vivo models, they are not suitable for pharmacologic applications due to their short half-life in vivo and large molecular size. In this paper, recent advances in MMP research and reports of clinical applications of synthetic MMP inhibitors for cancer patients are reviewed.

Further evidence for the value of the chemosensitivity test in deciding appropriate chemotherapy for advanced gastric cancer

BACKGROUND

The chemosensitivity test using the MTT endpoint is useful in predicting chemosensitivity.

PATIENTS AND METHODS

One hundred twenty-eight patients with advanced gastric cancer were enrolled in the study, which mitomycin C (MMC), doxorubicin (DXR), 5-fluorouracil (5-FU), and cisplatin (DDP) were used.

RESULTS

The corresponding efficacy rates were 12.5% for MMC, 6.3% for DXR, 5.4% for 5-FU and 13.4% for DDP. The overall predictive accuracy was 78% in the patients with measurable lesions. Among the patients without measurable lesions, 21 were treated with a curative operation, and 33 with a non-curative operation. In those patients undergoing curative surgery, the "adapted" group detected by MTT assay survived longer than "non-adapted" cases (p < 0.05).

CONCLUSIONS

The present study provides further evidence that the chemosensitivity test may be useful for evaluating appropriate chemotherapy for advanced gastric cancer.

[Laparoscopic surgery for early gastric cancer--its advantages and pitfalls]

We have successfully established two different laparoscopic procedures for early gastric cancer since March 1992, which are laparoscopic wedge resection of the stomach using a lesion-lifting method and laparoscopic intragastric mucosal resection. The indication is as follows; (A) mucosal cancer, (B) < 25 mm, if the lesion is elevated type, (C) < 15 mm and Ul (-), if the lesion is depressive type. The advantages of these methods are; 1) minimally invasiveness, 2) sufficient surgical margin, 3) feasibility of detailed histology, 4) feasivility of perigastric lymph node dissection. In contrast, there are several problems to be solved, which are; 1) preoperative diagnostic accuracy of the depth of cancer invasion, 2) possibility of reoperation because of sm invasion or lymphatic or venous invasion in final histology, 3) possibility of postoperative stenosis after laparoscopic intragastric mucosal resection for the lesion near the cardia, 4) incidence of metachronous multiple gastric cancer. In conclusion, if the indication is properly selected, these laparoscopic procedures are curative and minimally invasive treatment for early gastric cancer.

MKT-077, localized lipophilic cation: antitumor activity against human tumor xenografts serially transplanted into nude mice

BACKGROUND

In in vitro experiments, the localized lipophilic cation, MKT-077, demonstrated time- and concentration-dependent antitumor activity. In the present experiment, the in vivo antitumor activity of MKT-077 was evaluated using human tumor xenografts serially transplanted into nude mice.

MATERIALS AND METHODS

The antitumor efficacy of MKT-077 against five xenografts inoculated subcutaneously into nude mice was studied. Treatment with MKT-077 was initiated when the tumors started exponential growth. The antitumor activity of MKT-077 was assessed by a) the lowest value of the relative mean tumor weight of the treated:control tumors (T/CRW), where relative weight (RW) represented the change from baseline weight; and by b) the unadjusted weight of treated tumors at the end of the experiment.

RESULTS

When MKT-077 was administered continuously using the Osmotic Micropump, antitumor activity was positively correlated with exposure time and drug concentration from 7.5 to 40 mg/kg/day. The maximum tolerated dose was 20 mg/kg/day for 7 days. Co-4 (human colon cancer), St-4 (human gastric cancer), and CRL1420 (human pancreatic cancer) were evaluated as sensitive to MKT-077 in tested 5 strains.

CONCLUSION

The antitumor activity of MKT-077 was confirmed using human tumor xenografts in nude mice.