Rapid and accurate identification of bacteria utilizing laser-induced breakdown spectroscopy

Timely and accurate identification of harmful bacterial species in the environment is paramount for preventing the spread of diseases and ensuring food safety. In this study, laser-induced breakdown spectroscopy technology was utilized, combined with four machine learning methods - KNN, PCA-KNN, RF, and SVM, to conduct classification and identification research on 7 different types of bacteria, adhering to various substrate materials. The experimental results showed that despite the nearly identical elemental composition of these bacteria, differences in the intensity of elemental spectral lines provide crucial information for identification of bacteria. Under conditions of high-purity aluminum substrate, the identification rates of the four modeling methods reached 74.91%, 84.05%, 85.36%, and 96.07%, respectively. In contrast, under graphite substrate conditions, the corresponding identification rates reached 96.87%, 98.11%, 98.93%, and 100%. Graphite is found to be more suitable as a substrate material for bacterial classification, attributed to the fact that more characteristic spectral lines are excited in bacteria under graphite substrate conditions. Additionally, the emission spectral lines of graphite itself are relatively scarce, resulting in less interference with other elemental spectral lines of bacteria. Meanwhile, SVM exhibited the highest precision rate and recall rate, reaching up to 1, making it the most effective classification method in this experiment. This study provides a valuable approach for the rapid and accurate identification of bacterial species based on LIBS, as well as substrate selection, enhancing efficient microbial identification capabilities in fields related to social security and military applications.

Rapid selection of analytical lines for SAF-LIBS based on the doublet intensity ratios at the initial and final stages of plasma

Self-absorption-free laser-induced breakdown spectroscopy (SAF-LIBS) can directly obtain the applicable quasi-optically thin lines by determining the optimal acquisition delay time according to the intensity ratio of doublet lines at specific transition wavelength of the analyzed elements, thus eliminating the influence of self-absorption on quantitative results. In quantitative analysis of samples with a certain content range, the key to the convenient application of this technique is to rapidly select the suitable doublet lines for the element to be analyzed. The theoretical analysis shows that the evolution trend of doublet intensity ratio is monotonous under the assumptions that the plasma is uniform and in local thermal equilibrium (LTE) and the area density (Nl) is a constant, which is also confirmed by the experimental results of Cu and Al. Thus, a rapid spectral line selection criterion for SAF-LIBS applications is derived: only when the doublet intensity ratios measured at the initial and final stages of plasma induced by the boundary sample with the highest element content lie on both sides of the theoretical ratio, the doublet lines can reach quasi-optically thin during plasma evolution and are suitable for SAF-LIBS measurements. This new criterion is helpful to promote the practicality and industrial application of SAF-LIBS technology.

Resonance/non-resonance doublet-based self-absorption-free LIBS for quantitative analysis with a wide measurement range

A resonance/non-resonance, doublet-based, self-absorption-free, laser-induced breakdown spectroscopy (SAF-LIBS) technique is proposed for greatly expanding the measurement range of quantitative elemental analysis by using a quasi-optically thin line. The quasi-optically thin spectral line is obtained by matching the measured doublet atomic lines' intensity ratios with the theoretical one, and the applicable measurement range is expanded by utilizing the resonance and non-resonance lines. The specific calibration process consists of two parts: the nonlinear LIBS calibration and the linear SAF-LIBS calibration. For quantitative measurements, the approximate content of the unknown sample is determined first by using the LIBS calibration curve, and then the SAF-LIBS spectra and the resonance or non-resonance calibration curve that corresponds to the predetermined content are used for further implementing the quantitative analysis. Univariate quantitative analysis results of Cu show that this resonance/non-resonance doublet-based SAF-LIBS technique not only captures the quasi-optically thin spectral line in a wide range of elemental content, but also possesses high correlation coefficients of calibration curves, small relative errors of measurement and low limits of detection. The applicability and limitations of this technique are also discussed, and the evolution as well as the related major determinants of self-absorption are analyzed by taking advantage of the spatial-temporal evolution images of plasma emissivity.

[Technical advancement improves survival in patients with locally advanced non-small cell lung cancer (LA-NSCLC) receiving definitive radiotherapy]

OBJECTIVE

This study aimed to evaluate the impact of technical advancement of radiation therapy in patients with LA-NSCLC receiving definitive radiotherapy (RT).

METHODS

Patients treated with definitive RT (≥50 Gy) between 2000 and 2010 were retrospectively reviewed. Overall survival (OS), cancer specific survival (CSS), locoregional progression-free survival (LRPFS), distant metastasis-free survival (DMFS) and progression-free survival (PFS) were calculated and compared among patients irradiated with different techniques. Radiation-induced lung injury (RILI) and esophageal injury (RIEI) were assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events 3.0 (NCI-CTCAE 3.0).

RESULTS

A total of 946 patients were eligible for analysis, including 288 treated with two-dimensional radiotherapy (2D-RT), 209 with three-dimensional conformal radiation therapy (3D-CRT) and 449 with intensity-modulated radiation therapy (IMRT) respectively. The median follow-up time for the whole population was 84.1 months. The median OS of 2D-RT, 3D-CRT and IMRT groups were 15.8, 19.7 and 23.3 months, respectively, with the corresponding 5-year survival rate of 8.7%, 13.0% and 18.8%, respectively (P<0.001). The univariate analysis demonstrated significantly inferior OS, LRPFS, DMFS and PFS of 2D-RT than those provided by 3D-CRT or IMRT. The univariate analysis also revealed that the IMRT group had significantly loger LRPFS and a trend toward better OS and DMFS compared with 3D-CRT. Multivariate analysis showed that TNM stage, RT technique and KPS were independent factors correlated with all survival indexes. Compared with 2D-RT, the utilization of IMRT was associated with significantly improved OS, LRPFS, DMFS as well as PFS. Compared with 3D-CRT, IMRT provided superior DMFS (P=0.035), a trend approaching significance with regard to LRPFS (P=0.073) but no statistically significant improvement on OS, CSS and PFS in multivariate analysis. The incidence rates of RILI were significantly decreased in the IMRT group (29.3% vs. 26.6% vs.14.0%, P<0.001) whereas that of RIET rates were similar (34.7% vs. 29.7% vs. 35.3%, P=0.342) among the three groups.

CONCLUSIONS

Radiation therapy technique is a factor affecting prognosis of LA-NSCLC patients. Advanced radiation therapy technique is associated with improved tumor control and survival, and decreased radiation-induced lung toxicity.

A study of postoperative radiotherapy in patients with non-small-cell lung cancer: a randomized trial

PURPOSE

To study the value of postoperative radiotherapy for non-small-cell lung cancer (NSCLC) with positive regional lymph metastases (NI or N2) after radical surgery.

MATERIALS AND METHODS

From February 1982 to October 1995, 366 patients with NSCLC and N1 or N2 disease were randomized into postoperative radiotherapy (S + R) (183 patients) and no further treatment (S alone) (182 patients). Postoperative radiotherapy (RT) was administrated 3-4 weeks after radical operation. Irradiated fields covered the bronchial stump, ipsilateral hilum, and most of the mediastinum. The midplane dose was 6000 cGy/30 fractions/6 weeks, with the spinal cord limited to 4000 cGy/20 fractions/4 weeks or less. One hundred thirty-four patients in S + R group and 162 patients in S alone group were evaluated. Clinical data were comparable in both arms, except for the numbers of N2 patients.

RESULTS

The 3-year and 5-year overall survival rates were 51.9% and 42.9% in the S + R group and 50.2% and 40.5% in the S alone Group (p = 0.56). The 3-year and 5-year disease-free survival rates were 50.7% +/- 4.7% and 42.9% +/- 5.2% in the S + R group vs. 44.4% +/- 4.3% and 38.2% +/- 4.5% in the S alone group (p = 0.28), respectively. In the patients with NI or T3-4 tumors, there was a trend toward improved survival in the S + R group, especially in the patients with T3-4N1M0. These patients demonstrated 20% improvement in overall survival (p = 0.092) and greater than 20% better disease-free survival (p = 0.057). Postoperative RT reduced local recurrence but had no impact on distant metastases.

CONCLUSION

Postoperative RT significantly reduced local relapses, but did not improve overall survival, due to a high frequency of distant metastases in this patient group.

Randomized clinical trial on the combination of preoperative irradiation and surgery in the treatment of adenocarcinoma of gastric cardia (AGC)--report on 370 patients

PURPOSE

An attempt was made to define the role of radiotherapy before operation for AGC.

METHODS AND MATERIALS

From January 1978 to May 1989, a prospective randomized trial on preoperative radiotherapy (R+S) vs. surgery alone (S) for AGC was carried out in 370 patients. Patients were randomized into a combined group (R+S, 171 patients) or a surgery alone group (S, 199 patients) by the envelope method. 8-MV photon or telecobalt was used for the preoperative radiation therapy, using anterior-posterior opposing parallel fields to deliver 40 Gy to the cardia, lower segment of the esophagus, fundus, lesser curvature, and hepatogastric ligament. Surgery was performed after 2 to 4 weeks rest.

RESULTS

The 5- and 10-year survival rates of the R+S Group and the S Alone Group were 30.10% and 19.75%, 20.26% and 13.30%, respectively. The survival curves of these two groups diverged right from the beginning after the operation over the ninth year. Statistics by Kaplan-Meier log rank test proves that the difference is significant (chi2 = 6.74, p = 0.0094). The immediate results were: resection rate 89.5% and 79.4% (p < 0.01); pathologic stage after resection T2 12.9% and 4.5% (p < 0.01), T4 40.3% and 51.3% (p < 0.05), lymph node metastasis rates 64.3% and 84.9% (p < 0.001); operative mortality rates 0.6% and 2.5%; intrathoracic leak rates 1.8% and 4.0%, respectively. The causes of failure were: local uncontrol and recurrence 38.6% vs. 51.7% (p < 0.025), regional lymph node metastasis 38.6% vs. 54.6% (p < 0.005), distant metastasis 24.3% vs. 24.7%.

CONCLUSION

Preoperative radiation therapy is able to improve the results of surgery for adenocarcinoma of the gastric cardia.

Prospective multimodality treatment of SCLC--experience during the past 18 years

Lung cancer has been one of the leading malignancies in China. Since 1989 it has ranked first among common malignancies in the male population, and second in females. In 1975, a multimodality treatment study group for lung cancer was organized in our institute. The group has since expanded to 15 institutions in the Beijing and Tianjin area during the past four years. The present communication is based on our experiences and data, and tries to explain the treatment strategy of our study group.

[Compensation and adaptation to hypoxia in clinical hypoxyradiotherapy]

During the whole course of clinical hypoxyradiotherapy, patients may experience with 25-35 sessions of the sustained hypoxic disciplines. It is quite possible for them to develop some compensation or adaptation to hypoxia. In the present study, analysis of parameters, derived from both hypoxic oxygen tolerance tests before and after the course, showed the evidence of the compensatory mechanism to transient systemic hypoxia induced by breathing hypoxic gas. The conclusion may be different from what is generally believed. Its physiologic basis, development and clinical tactics for counteraction were investigated.

Preliminary experience in HDR brachytherapy for 72 nasopharyngeal carcinoma patients

From April 1989 to July 1991, 72 patients with residual or recurrent nasopharyngeal carcinoma (NPC) were treated by MSH Ir-192 brachytherapy or combined external radiation therapy. All were proven histologically. 39 patients with residual disease and 6 with recurrent lesion at the primary site were identified after one or more courses of radical external radiation. Eleven patients had received brachytherapy for boost therapy after one or more courses of external radiation. Sixteen were treated with a planned protocol of external irradiation combined with intracavitary brachytherapy. The overall local control rate was 93.3%; the local control rate for residual and recurrent disease was 100% and 50%, respectively. Soft palate perforation was observed in 3 patients. Brachytherapy is believed to be a useful treatment for residual or recurrent NPC following radical external radiation.

Curative radiotherapy of early operable non-small cell lung cancer

The results of 44 patients with early operable non-small cell lung cancer treated from January 1975 through 1981 are retrospectively analysed. All were proven by pathology and/or cytology and denied surgery in our joint Chest Clinic for various reasons. 55-70 Gy/6-7 weeks was delivered by conventional fractionation through A-P portals by telecobalt and/or 25-35 MeV high energy electron beam or 8 MV X-ray. 40 Gy/4 weeks was given prophylactically to the mediastinum. The 1-, 3-, and 5-year survival rates, 93, 55, and 32%, are superior to what is reported in the literature. In the present series, the favorable factors are: (1) patients without any intercurrent disease but refused operation; (2) T1 lesions; (3) complete regression of the lesion at the conclusion of radiotherapy; (4) doses ranging from 69 to 70 Gy. It is shown that early non-small cell lung cancer can be cured by radiotherapy alone giving survival rates comparable to surgery. Prospective randomized clinical trials are warranted.

Randomized clinical trial on the combination of preoperative irradiation and surgery in the treatment of esophageal carcinoma: report on 206 patients

From June 1977 to May 1985, a prospective randomized clinical trial on pre-operative radiation for esophageal carcinoma was carried out in 206 patients. Lesions under 8 cm in length and patients younger than 65 years, at least on semi-liquid diet and not contra-indicated for surgery were randomized into a combined group (104 patients) or a surgery alone group (102 patients). Eight MV X ray units were used for the pre-operative radiation using A-P portals to deliver 4,000 cGy to the whole mediastinum and the left gastroepiploic lymphatic chain. Surgery was carried out after 2 to 4 week's rest. The immediate results of the combined group and the surgery alone group were: resection rate 93% and 85%, operative mortality 5% and 6%, intra-thoracic anastomotic leak 0% and 1%, positive pathology at the esophageal stump 0% and 2%, and lymph nodes metastasis 27% and 35% respectively. The 5-year survival rates of the combined group and the surgery alone group were 35% and 30%. We have noticed that those patients with lesions showing radiation reaction of grade III gave a 5-year survival of 50% (12/24). Because intra- and extra-thoracic lymphnode metastasis caused failures (41% and 34% of these two groups), increasing the preoperative tumor dose to 60 Gy or designing post-operative irradiation to cover the bilateral supraclavicular areas was necessary. The whole mediastinum and the left gastroepiploic lymphatics could further improve the results of surgery. Further studies are needed.

[Value of prophylactic irradiation to supraclavicular areas in small cell lung carcinoma--analysis of 104 patients]

A series of 104 patients with limited small cell lung carcinoma was treated by combination of chemotherapy and radiotherapy from August 1975 to July 1981. 104 patients were divided into three groups: prophylactic irradiation to supraclavicular areas (14 patients), non-prophylactic group (72 patients), non-prophylactic irradiation with positive supraclavicular lymph node metastasis after the treatment (18 patients). The 5 year survival rates of the three groups were 14%, 6% and 0%. Distant metastasis rates after the treatment were 36%, 52% and 61%, respectively. The supraclavicular lymph node metastasis rate after the treatment was higher in patients with intra-thoracic lymph node metastasis before the treatment (25%) than in those without this metastasis (0%). It is suggested that, for small cell lung cancer patients, especially with intra-thoracic lymph node metastasis before the treatment, prophylactic irradiation to the supraclavicular areas be valuable.

[COMVp regimen in the treatment of small cell lung cancer--report of 106 patients]

One hundred and six consecutive small cell lung cancer patients were treated by a combination regimen COMVp (CTX 1,000-1,400 mg IV D 1,8; VCR 1-2 mg IV D 1,8; MTX 20-40 mg IV or IM D 3,5,10,12; VP-16 100 mg IV drip D 3-7; three weeks as a cycle and 2-3 cycles as a course) in our hospital during 1983 to 1984. Among the 95 patients who were evaluated, 10 (10.5%) gave CR, 57 (60%) PR, 19 (20%) no change and 9 (9.5%) progression. The overall response rate was 70.5%. In this paper, factors influencing the response and side effects are also analysed. The data show that COMVp regimen is one of the good front line combination chemotherapy regimens currently available in the management of small cell lung cancer.

[Carcinoma of esophagus treated by 8MV X-ray and checked by simulator]

From January 1, 1978 to December 31, 1983, 570 patients with carcinoma of esophagus were treated by 8 MV X-ray and checked by the Philips simulator. In order to assess their value, a series of 3,798 patients reported previously was used for comparison. To further evaluate the effect of 8 MV X-ray and simulator separately, a series of 154 patients was treatment by non-8 MV X-ray during the same period. The results showed that the 1 and 3 year survival rates of 8 MV X-ray series were better than the 3,798 series (P less than 0.01). It means that after the use of simulator and 8 MV X-ray the survival rates were improved. As compared to the radiation other than 8 MV X-ray, there was no difference between 8 MV X-ray and non-8 MV X-ray series, which means that the improvement may have been due to the better localization by the simulator. Having more importance, no radiation myelitis was found after the use of simulator. The sex, age, length, location, X-ray type, NSD and causes of failure were compared in these groups.

[Superior sulcus cancer of the lung--report on 45 patients]

From 1960 to 1980, 45 patients with superior sulcus cancer of the lung were seen in our hospital. 39 were male and 6 were female. The youngest was 28 years old and the eldest was 75. The presenting symptoms and signs were back and shoulder pain in 32 patients, compression of the brachial plexus in 17, Horner's syndrome in 12, supraclavicular mass in 11, superior cava vena obstruction in 4, shadow in the apex in 45, destruction of the rib in 19 (10 in the second rib), destruction of the adjacent vertebra in 8 (5 in T3) and destruction of the clavicle in 1. In 18 patients proved by pathology and cytology, 8 were adenocarcinoma, 3 squamous cell carcinoma, 3 undifferentiated and 4 unclassified carcinoma. 27 patients were diagnosed by X-ray films. 40 patients were admitted for treatment. 3 recieved chemotherapy alone and all of them died in one year. Of the 6 treated by radiation plus chemotherapy, 3 survived for one year but all died in two years. 2 were treated by radiation plus operation and none survived for more than 3 years. 29 were treated by radiation only. The 1, 3 and 5 year survival rates were 51%, 13.7% and 6.9%. Destruction of the rib or the adjacent vertebral body was irrelative to the prognosis but the presence of supraclavicular mass reduced the survival rate. Cause of death was local recurrence in 48% (13/27) and distant metastasis in 48% (13/27). The authors suggest that radical en bloc resection together with radiation the worth further study.

[Double primary cancer in the larynx and lung--report of 12 cases]

12 patients with double primary cancers in the larynx and lung were treated from 1958 to 1984. The incidence is 1.2% (12/943) of laryngeal carcinomas, 1.3% (12/904) of multiple primary cancers, 1.4% (12/873) of double primary cancers and 39% (12/31) of double primary cancers related to laryngeal cancers. There were 9 male and 3 female. 11 of the first primary cancers occurred in the larynx and only one in the lung. All were proved to be squamous cell carcinoma. In the 11 patients whose second primaries occurred in the lung, 4 were proved to be squamous cell carcinoma, one adenocarcinoma, one oat cell carcinoma, one poorly differentiated carcinoma and one cancer unclassified. Of 10 patients in whom both the first and the second primary cancer were treated, 6 survived for more than 2 years, 4 for 3 years and one for 5 years after the second treatment. It seems that double primary cancers of the larynx and lung could yield favorable results.

[Irradiation of recurrent esophageal carcinoma]

81 patients with recurrent esophageal carcinoma after radical radiotherapy were irradiated from Mar. 1958 to Dec. 1973. The results were compared with those of 137 patients with untreated postirradiation recurrences in the same period. Of these 81 patients, 21 failed to complete the second course due to esophageal perforation (8 cases), fatal hemorrhage (4 cases) and deterioration of the general condition (9 cases). The improvement rate of symptoms was 19.75% and that of barium meal was 44.44%. The mean survival of the re-irradiation group was 6.59 +/- 4.66 months in contrast to that of the control group, 4.51 +/- 4.40 months. There was significant difference between these two groups (P less than 0.01). It is shown that the total dose of re-irradiation has no significant effect on the survival. the survival of patients receiving 4,000 rad or less was 5.92 +/- 4.53 months and that of patients receiving more than 4,000 rad was 7.86 +/- 4.72 months (P greater than 0.05). There is no statistical significance in between. We believe that re-irradiation is capable of relieving the symptoms and prolonging survival. It should be selectively used in the patients with recurrent esophageal carcinoma after radical radiotherapy.

Alternative types of duodenal ulcer induced in mice by partial X irradiation of the thorax

The present study extends our earlier observations [A. Michalowski, Br. J. Radiol. 54, 713 (1981); A. Michalowski and J. Burgin, in Progress in Radio-Oncology II, pp. 105-110] on gastrointestinal pathology in thorax-irradiated female CFLP mice. It shows that exposure of the lower mediastinum to single doses of 14-30 Gy X rays results in the formation of the proximal duodenal ulcer accompanied frequently by erosion of the antral gastric mucosa. X irradiation of the lateral thoracic fields is responsible for single ulcers in the proximity of duodenal papilla, often associated with a circumscribed area of degeneration of the fundic mucosa of the stomach. In view of the small amount of radiation received by the subdiaphragmatic parts of the alimentary tract, these gastro-duodenal lesions represent abscopal effects of thoracic irradiation.

The results of radiation therapy in advanced carcinoma of the lung in the Beijing region of China

From 1958 to 1973, 682 patients with lung cancer were treated by radiation therapy in the Cancer Institute, Chinese Academy of Medical Sciences, Beijing, China. The clinical presentation, sex, age, histology and stage and palliative effects of radiation therapy were reported. The 1-, 3- and 5-year survival rates were 40.62, 8.94 and 3.81%, respectively. The prognostic factors such as staging, histology, combination with chemotherapy and response of tumours are discussed. The causes of failure are also analysed. It is suggested that improving the local control rate of squamous cell carcinoma would increase the survival rate.