Discovery of Novel TLR7 Agonists as Systemic Agent for Combination With aPD1 for Use in Immuno-oncology

We have designed and developed novel and selective TLR7 agonists that exhibited potent receptor activity in a cell-based reporter assay. In vitro, these agonists significantly induced secretion of cytokines IL-6, IL-1β, IL-10, TNFa, IFNa, and IP-10 in human and mouse whole blood. Pharmacokinetic and pharmacodynamic studies in mice showed a significant secretion of IFNα and TNFα cytokines. When combined with aPD1 in a CT-26 tumor model, the lead compound showed strong synergistic antitumor activity with complete tumor regression in 8/10 mice dosed using the intravenous route. Structure-activity relationship studies enabled by structure-based designs of TLR7 agonists are disclosed.

[Clinical and pathological analysis of 345 cases of vulvar lichen sclerosus and a preliminary study on the frequency of maintenance treatment]

Objective: To analyze and summarize the clinical and pathological characteristics, management, and efficacy of patients with vulvar lichen sclerosus (VLS) through a single center large sample study, and preliminarily to explore the frequency of maintenance treatment medication for VLS. Methods: The clinical data of VLS patients in Obstetrics and Gynecology Hospital of Fudan University from 2018 to 2021 were retrospectively collected. The clinicopathological characteristics (patients' age, course of disease, complicated disease history, family history, symptoms, signs and pathology), treatment and effects were retrospectively analyzed. The patients in the maintenance treatment stage were followed up regularly to explore the minimum frequency of individual medication to maintain the stability of the disease. Results: (1) General situation: a total of 345 patients with VLS were included in this study. The average age was (50.4±14.7) years (ranged from 8 to 84 years old), prevalence was highest in the 50-59 years group (30.1%, 104/345). Immune diseases occurred in 18.6% (33/177) of patients, 24.3% (43/177) of patients had allergic skin diseases, and 5.6% (10/177) of the patients' immediate family members had chronic vulvar pruritus or vulvar hypopigmentation. (2) Clinical features: the most common symptom was vulvar pruritus (96.1%, 196/204) among 204 patients with recorded symptoms. The most common sign was hypopigmentation of the vulva (96.3%, 206/214). The most common involved sites were labia minora (70.3%, 142/202), labia majora (67.8%, 137/202), and labial sulcus (59.4%, 120/202). The cumulative number of sites involved in 62 vulvar atrophy patients (2.7±1.1) was significantly higher than that in 152 non-atrophy patients (2.2±1.0; t=3.48, P=0.001). The course of vulvar atrophy was (9.3±8.5) years, which was significantly longer than that of non-atrophy patients [(6.6±5.6) years; t=2.04, P=0.046]. (3) Pathological features: among the 286 patients with electronic pathological sections, the most common pathological feature in the epidermis was epithelial nail process passivation (71.3%, 204/286). The common pathological features in the dermis were interstitial collagenization (84.6%, 242/286), and inflammatory cell infiltration (73.8%, 211/286). (4) Treatment: 177 patients received standardized treatment after diagnosis and were followed up regularly in our hospital. In the initial treatment stage, 26.0% (46/177) of the patients were treated with 0.05% clobetasol propionate cream, and 74.0% (131/177) of the patients were treated with 0.1% mometasone furoate ointment. The complete remission rates of the two methods were respectively 80.4% (37/46) and 74.0% (97/131), and there was no statistically significant difference (χ²=0.76, P=0.385). During maintenance treatment, 27.1% (48/177) of the patients took the medication twice a week, 35.0% (62/177) took the medication once a week, and 37.9% (67/177) took the medication once every 10 days. During follow-up after 6 months of maintenance treatment, there were no patients with recurrence of pruritus or progression of vulvar signs. Conclusions: The majority of VLS patients have itching, hypopigmentation, involvement of labia minora and labia majora, progressive atrophy, and inflammatory infiltration of dermis. Local treatments of mometasone furoate and clobetasol propionate have good initial therapeutic effects. The frequency exploration of individualized maintenance treatment could minimize the occurrence of adverse reactions when ensuring the stability of the patients' condition.

A prospective multicentre controlled study of Gaoweikang (Chinese multiherb extract-based tincture) used in high-risk HPV infections

OBJECTIVE

The aim of the study was to investigate the safety and antiviral efficacy of a Chinese multiherb extract-based tincture (GWK) on a population of patients with high-risk human papilloma (hrHPV) infections and hrHPV-caused cervical low-grade squamous intraepithelial lesions (LSILs).

PATIENTS AND METHODS

Patients with persistent hrHPV infection were enrolled in Group A, including A1 subjects, who received the intervention, and A2 subjects, who received the control. Patients with hrHPV infection causing cervical LSIL were enrolled in Group B, which included B1 subjects, who received the intervention, and B2 subjects, who served as the control. For Groups A1 and B1, hrHPV was tested at 3 months (M3) and 6 months (M6) after the intervention. The side effects were also analyzed.

RESULTS

At baseline (D0), a total of 99 patients were enrolled in Group A, with 50 subjects in Group A1 and 49 subjects in Group A2. A total of 91 patients were enrolled in Group B, with 45 subjects in Group B1 and 46 subjects in Group B2. There was no significant difference in the characteristics, including average age, age stratification, and HPV genotype. At M6, both Group A1 and Group B1 had a higher hrHPV clearance rate than the control group (A1/A2: 80.0% vs. 20.4%; B1/B2: 64.4% vs. 15.2%, p<0.001). At M6, the effective rates of Group A1 and Group B1 were 84% (42/50) and 68.9% (31/45), respectively. The side effect rates of Groups A1 and B1 were 11.5% (6/52) and 11.1% (5/45), respectively. Most adverse reactions involved local discomfort, including vulvar erythema, vulvar itch, increased vaginal discharge, cervical bleeding, and mild pain in the lower abdomen. Univariate logistic regression analysis showed that the intervention had an OR of 12 (95% CI 4.431-32.50) for clearing persistent HPV infection (p<0.001). For cervical LSIL, the intervention had an OR of 10.1 for clearing persistent HPV infection (95% CI 3.68-27.7) (p<0.001).

CONCLUSIONS

The results of this study suggest that the Chinese multiherb extract-based tincture GWK is safe and well tolerated. Furthermore, this preliminary study showed that this Chinese multiherb extract-based tincture is helpful for promoting HPV clearance in cases of persistent HPV and HPV-induced LSIL.

Sintering Temperature Effect of Near-Zero Thermal Expansion Mn3Zn0.8Sn0.2N/Ti Composites

Metal matrix composites with near-zero thermal expansion (NZTE) have gained significant popularity in high-precision industries due to their excellent thermal stability and mechanical properties. The incorporation of Mn3Zn0.8Sn0.2N, which possesses outstanding negative thermal expansion properties, effectively suppressed the thermal expansion of titanium. Highly dense Mn3Zn0.8Sn0.2N/Ti composites were obtained by adjusting the fabrication temperature. Both composites fabricated at 650 °C and 700 °C exhibited NZTE. Furthermore, finite element analysis was employed to investigate the effects of thermal stress within the composites on their thermal expansion performance.

[Detection rate and clinical characteristics of vulvar squamous intraepithelial lesion]

Objective: To explore the detection rate, clinical characteristics of vulvar squamous intraepithelial lesion (SIL). Methods: Women diagnosed with vulvar high-grade squamous intraepithelial lesions (HSIL) through colposcopy-guided biopsy from January 1, 2018 to August 31, 2022 in Obstetrics and Gynecology Hospital of Fudan University were included in a 1∶1 ratio with patients diagnosed with vulvar low-grade squamous intraepithelial lesions (LSIL) during the same period. Clinical characteristics including human papillomavirus (HPV) infection rate, genotype, cytology result, colposcopy impression, and lesion location were retrospectively analyzed. Results: (1) The proportion of vulvar SIL detected by colposcopy-guided biopsy increased annually from 2018 to 2022, with rates of 1.64% (740/45 057), 2.34% (1 110/47 402), 2.68% (1 108/41 335), 3.26% (1 536/47 078), 3.31% (667/20 155), with an average rate of 2.57% (5 161/201 027). (2) A total of 1 096 cases of vulvar HSIL and 1 096 cases of vulvar LSIL were included. The overall infection rate of HPV was 92.7% (1 993/2 150), with higher infection rate in vulvar HSIL patients than that in vulvar LSIL patients [96.0% (1 012/1 054) vs 89.5% (981/1 096); χ2=33.62, P<0.001]. Among vulvar HSIL patients, the common HPV genotype from high to low were HPV 16 (66.7%), HPV 52 (14.3%), and HPV 58 (10.0%). For vulvar LSIL patients, the most common HPV genotype were respectively HPV 16 (24.9%), HPV 6 (20.1%) and HPV 52 (17.1%). The overall sensitivity rate of cytology was 53.6%, with no significance difference between vulvar LSIL and HSIL groups (54.3% vs 52.9%; χ2=0.40, P=0.526). The accuracy of colposcopy impression for vulvar HSIL was lower than that for vulvar LSIL [40.2% (163/405) vs 81.7% (380/465); χ2=158.72, P<0.001]. About 57.3% (1 257/2 192) of the patients had concomitant cervical and vaginal lesions, with a higher rate in vulvar HSIL group than that in vulvar LSIL group [62.6% (686/1 096) vs 52.1% (571/1 096); χ2=24.67, P<0.001]. Unifocal lesion was the main type, with no significance difference between vulvar LSIL and HSIL groups [81.4% (381/468) vs 82.5% (386/468); χ2=0.18, P=0.671]. The most common lesion locations were the posterior commissure, followed by labia minora, vaginal vestibule, labia majora, perianal and clitoris. Conclusions: The detection rate of vulvar SIL under colposcopy is about 3%, and the infection rate of HPV is 92.7%. Vulvar SIL, especially vulvar HSIL, is likely to cause concomitant cervical and vaginal lesions. The accuracy of colposcopy in diagnosing vulvar HSIL is low. Therefore a comprehensive and careful examination of the vulva is necessary and suspicious vulvar lesions should be undergone colposcopy-guided biopsy for diagnosis.

[Stratified research on related risk factors of CINⅡ+ in CINⅠ patients diagnosed by endocervical curettage under colposcopy]

Objective: To estimate risks of cervical intraepithelial neoplasia (CIN) Ⅱ or worse (CINⅡ⁺) on loop electrosurgical excisional procedure (LEEP) specimens with the diagnosis of endocervical curettage (ECC) CINⅠ compared with biopsy CINⅠ, and also to investigate the hierarchical management scheme of ECC CINⅠ based on the relevant factors of CINⅡ⁺ risk. Methods: (1) A retrospective computer-based research for subjects enrolled in the Obstetrics and Gynecology Hospital, Fudan University from Jan. 2013 to Jun. 2021 was performed. The case group comprised women with an ECC CINⅠ (ECC results of CINⅠ with colposcopy-directed biopsy results ≤CINⅠ), and the control group comprised women with a biopsy CINⅠ (colposcopy-directed biopsy results of CINⅠ with negative ECC findings) were divided after LEEP surgery and diagnosis in the next three months. The clinical data of all patients before LEEP were analyzed, and the pathological diagnosis between two groups after LEEP was compared. (2) Variables, including age, cytology, high-risk human papillomavirus (HR-HPV), ECC results, cervical transformation zone (TZ) and colposcopy impression, were included to describe the characteristics and compare the incidence of LEEP CINⅡ⁺. (3) Univariate analysis and Multivariate logistic regression method were used to analyze the related factors that affect the LEEP CINⅡ⁺ in CINⅠ patients. Further, the specific risks caused by related factors and conduct a stratified study in LEEP CINⅡ⁺ were analyzed. Results: (1) Overall, 2 581 women with ECC CINⅠ or biopsy CINⅠ diagnosis who underwent LEEP participated in the study with the mean age (43.6±9.5) years old. Chi square test found that the age and cytology of patients in ECC CINⅠ group were statistically different from those of biopsy CINⅠ group (all P<0.05). There was no significant difference in HR-HPV detection, TZ type and colposcopy impression between the two groups (all P>0.05). ECC CINⅠ comprised 957 women, with LEEP histopathology results revealing 288 (30.1%, 288/957) CINⅡ⁺, which was significantly higher than that of biopsy CINⅠ which was comprised 1 624 women, with LEEP histopathology results showing 333 (20.5%, 333/1 624) CINⅡ⁺ (χ²=30.31, P<0.001). (2) Compared by LEEP CINⅡ⁺ with LEEP ≤CINⅠ group, there were no significant difference in the age, HR-HPV, colposcopy impression (all P>0.05); but there were significantly differences in cytology, ECC CINⅠ, type Ⅲ TZ (all P<0.001). Multivariate logistic regression analysis showed that atypical squamous epithelial cells (ASC-H; OR=2.77, 95%CI: 2.04-3.77), high-grade squamous intraepithelial lesions and worse (HSIL⁺; OR=2.93, 95%CI: 2.24-3.81), ECC CINⅠ (OR=1.89, 95%CI: 1.56-2.29) and type Ⅲ of TZ (OR=1.76, 95%CI: 1.45-2.11) were independent risk factors for LEEP CINⅡ⁺ (all P<0.05). (3) When cytology was ≤low-grade squamous intraepithelial lesion (LSIL) and ≥ASC-H, the detection rate of CINⅡ⁺ in ECC CINⅠ was significantly higher than that of biopsy CINⅠ (all P<0.001). In ECC CINⅠ, the rate of CINⅡ⁺ with cytology ≤LSIL was significantly lower than that in cytology ≥ASC-H (56.0% vs 25.9%; χ²=49.38, P<0.001). In type Ⅰ/Ⅱ of TZ, the detection rate of CINⅡ⁺ between ECC CINⅠand biopsy CINⅠ had no significantly different; while in type Ⅲ of TZ, there was significantly different (72.7% vs 46.2%; χ²=4.02, P=0.045). In ECC CINⅠ, type Ⅲof TZ was significantly higher in the rate of CINⅡ⁺ than that of type Ⅰ/Ⅱ of TZ (72.7% vs 21.7%; χ²=16.38, P<0.001). When cytology ≥ASC-H, type Ⅲ of TZ and colposcopy impression of HSIL were combined, the rate of CINⅡ⁺ in ECC CINⅠ was 6/6 while 1/3 in biopsy CINⅠ. Conclusions: Cytology ≥ASC-H, ECC CINⅠ and type Ⅲ TZ are the risk factors of LEEP CINⅡ⁺. However, cytology ≥ASC-H is more valuable in predicting LEEP CINⅡ⁺ than ECC CINⅠ. For patients with ECC CINⅠ to perform LEEP, it is recommended that cytology ≥ASC-H is taken as the first level stratification, and type Ⅲ TZ is taken as the second level stratification. The colposcopy impression of patients is recommended for a reference parameter.

Configuration Design and Dynamic Characteristics Analysis of Spacecraft Membrane Sunshield

To meet the needs of large space telescopes, such as light weight, high folding ratio, and low manufacturing cost, a flexible deployable regular hexagonal membrane sunshield is proposed in this paper. Firstly, the dynamic equation of the membrane plane is established by the micro-element method. Then, the response surface method is used to obtain the mathematical model of the fundamental frequency of the membrane sunshield. The factors influencing this model, such as the corner pulling force, the effective circle radius, and the edge arch height, are analyzed. By combining the formula of the fundamental frequency of the membrane sunshield and the effective area ratio of the sunshield, the multi-objective optimization function of the fundamental frequency of the membrane sunshield is obtained. A scaled-down experimental prototype of the membrane sunshield is built, and the modal test is performed on the thin membrane plane with a circular fixed boundary in the middle. Comparing the experimental results with the finite element simulation results, the mode shape and the fundamental frequency are highly consistent. This proves that the model can be used to solve the fundamental frequency of the membrane sunshield under the same boundary.

Stress Superposition Method and Mechanical Properties Analysis of Regular Polygon Membranes

In this paper, the stress superposition method (SSM) is proposed to solve the stress distribution of regular polygon membranes. The stress-solving coefficient and the calculation formula of arbitrary point stress of regular polygon membrane are derived. The accuracy of the SSM for calculating stresses in regular polygonal membranes is verified by comparing the calculation results of the SSM with the finite element simulation results. This article is the first to propose a method to investigate the response of the arch height of the membrane curved edge to the membrane's mechanical properties while keeping the effective area constant. It is found that the equivalent stress and the second principal stress at the midpoint of the membrane curved edge are effectively increased with the increase of the arch height of the curved edge. The second principal stress at the edge region of the membrane is relatively small, leading to the occurrence of wrinkles. When the stress at the midpoint of the curved edge is equal to that at the center of the membrane, the membrane plane attains the maximum stiffness and reduces the possibility of wrinkling at the edge.

Tri-domain proteins 27 reduce inflammation and apoptosis in HK-2 cells and protect against acute kidney injury in mice

OBJECTIVE

The kidney is one of the most commonly damaged organs in sepsis. Acute kidney injury (AKI) induced by sepsis is a clinically dangerous disease with a high mortality rate. Therefore, it is particularly important to find a way to prevent and treat sepsis-induced AKI.

MATERIALS AND METHODS

Human renal tubular epithelial cell line (HK-2) and 8-week-old C57BL/6 mice were used. Lipopolysaccharide (LPS) was used to induce HK-2 cell injury and mouse AKI. Lentiviruses overexpressing TRIM27 were constructed to increase TRIM27 expression in HK-2 cells. Then, the effects of TRIM27 on the inflammation and apoptosis of HK-2 cells were analyzed, and those of TRIM27 recombinant protein on AKI in mice was detected by immunohistochemical staining and Western blot.

RESULTS

It was found that TRIM27 overexpression reduced the expressions of inflammatory factors and signaling molecules in apoptosis-related pathways in HK-2 cells, but increased the ratio of Bcl-2 to Bax in HK-2 cells, indicating the anti-apoptotic effect of TRIM27. Toll-like receptor 4 (TLR4)/NF-κB signaling pathway is an important mechanism of LPS mediated renal injury, and TRIM27 overexpression in HK-2 cells significantly inhibited the activity of TLR4/NF-κB signaling pathway. In addition, AKI was significantly relieved in mice treated with TRIM27 recombinant.

CONCLUSIONS

TRIM27 exerts anti-inflammatory and anti-apoptotic effects by inhibiting the TLR4/NF-κB signaling pathway, which effectively alleviates LPS-induced HK-2 cell damage and mouse AKI.

Synthesis and Biological Evaluation of a Carbamate-Containing Tubulysin Antibody-Drug Conjugate

Antibody-drug conjugates (ADCs) use antibodies to deliver cytotoxic payloads directly into tumor cells via specifically binding to the target cell surface antigens. ADCs can enhance the anti-tumor effects of antibodies, and increase the delivery of cytotoxic payloads to cancer cells with a better therapeutic index. An ADC was prepared with a potent carbamate-containing tubulysin analogue attached to an anti-mesothelin antibody via a Cit-Val dipeptide linker. An aniline functionality in the tubulysin analogue was created to provide a site of linker attachment via an amide bond that would be stable in systemic circulation. Upon ADC internalization into antigen-positive cancer cells, the Cit-Val dipeptide linker was cleaved by lysosomal proteases, and the drug was released inside the tumor cells. The naturally occurring acetate of tubulysin was modified to a carbamate to reduce acetate hydrolysis of the ADC in circulation and to increase the hydrophilicity of the drug. The ADC bearing the monoclonal anti-mesothelin antibody and the carbamate-containing tubulysin was highly potent and immunologically specific to H226 human lung carcinoma cells in vitro, and efficacious at well-tolerated doses in a mesothelin-positive OVCAR3 ovarian cancer xenograft mouse model.

Adnectin-drug conjugates for Glypican-3-specific delivery of a cytotoxic payload to tumors

Tumor-specific delivery of cytotoxic agents remains a challenge in cancer therapy. Antibody-drug conjugates (ADC) deliver their payloads to tumor cells that overexpress specific tumor-associated antigens-but the multi-day half-life of ADC leads to high exposure even of normal, antigen-free, tissues and thus contributes to dose-limiting toxicity. Here, we present Adnectin-drug conjugates, an alternative platform for tumor-specific delivery of cytotoxic payloads. Due to their small size (10 kDa), renal filtration eliminates Adnectins from the bloodstream within minutes to hours, ensuring low exposure to normal tissues. We used an engineered cysteine to conjugate an Adnectin that binds Glypican-3, a membrane protein overexpressed in hepatocellular carcinoma, to a cytotoxic derivative of tubulysin, with the drug-to-Adnectin ratio of 1. We demonstrate specific, nanomolar binding of this Adnectin-drug conjugate to human and murine Glypican-3; its high thermostability; its localization to target-expressing tumor cells in vitro and in vivo, its fast clearance from normal tissues and its efficacy against Glypican-3-positive mouse xenograft models.

RN1, a novel galectin-3 inhibitor, inhibits pancreatic cancer cell growth in vitro and in vivo via blocking galectin-3 associated signaling pathways

Galectin-3 (Gal-3) has been implicated in pancreatic ductal adenocarcinoma (PDAC), and its candidacy as a therapeutic target has been evaluated. Gal-3 is widely upregulated in tumors, and its expression is associated with the development and malignancy of PDAC. In the present study, we demonstrate that a polysaccharide, RN1, purified from the flower of Panax notoginseng binds to Gal-3 and suppresses its expression. In addition, RN1 markedly inhibits PDAC cells growth in vitro, in vivo and in patient-derived xenografts. Mechanistically, RN1 binds to epidermal growth factor receptor (EGFR) and Gal-3, thereby disrupting the interaction between Gal-3 and EGFR and downregulating extracellular-related kinase (ERK) phosphorylation and the transcription factor of Gal-3, Runx1 expression. Inhibiting the expression of Runx1 by RN1, suppresses Gal-3 expression and inactivates Gal-3-associated signaling pathways, including the EGFR/ERK/Runx1, BMP/smad/Id-3 and integrin/FAK/JNK signaling pathways. In addition, RN1 can also bind to bone morphogenetic protein receptors (BMPR1A and BMPR2) and block the interaction between Gal-3 and the BMPRs. Thus, our results suggest that a novel Gal-3 inhibitor RN1 may be a potential candidate for human PDAC treatment via multiple targets and multiple signaling pathways.

Structure−Activity Relationship Studies of Illudins: Analogues Possessing a Spiro-cyclobutane Ring

Bicyclic and tricyclic analogues of anticancer sesquiterpene illudin S have been synthesized. These contain a spiro-cyclobutane instead of spiro-cyclopropane structure. The cytotoxicity of the former is less than that of the corresponding cyclopropane-containing compounds.

[Can esophagogastric anastomosis prevent gastroesophageal reflux]

OBJECTIVE

To investigate the possible anti-reflux function of esophagogastric anastomosis in the patients after receiving resection of cardiac cancer.

METHODS

One hundred and ninety-two patients were studied by video-assisted gastroscopy, manometry, 24-h pH esophageal monitoring, radioscintigraphy and scanning electron microscopy.

RESULTS

Abnormalities were found in 90.2% of patients through endoscopy. Resting pressure in esophageal body was higher than that in normal controls, and in the stomach, lower. Twenty-four hour pH monitoring demonstrated that gastroesophageal reflux (GER) did not occur when the patients slept in semi-reclining position, and occurred in all patients when slept in supine position. Scintigraphic study showed that 2/3 of the patients had reflux, occurrence of which was not affected by the length of postoperative period. Scanning electron microscopic examination showed that degeneration, exfoliation of esophageal mucosal epithelial cell, and derangement of micro-fold and inflammatory oedema of cytomembrane may be directly caused by reflux.

CONCLUSIONS

GER exists in the majority of the patients after esophagogastrectomy and esophagogastrostomy for cardiac cancer. The occurrence of GER is not affected by the length of postoperative period. Some detecting methods fail to show the existence of GER, and 24-h pH monitoring is the most reliable method for detecting GER. Sleep in semireclining position is an effective method of preventing GER in postoperative patients.

[Lugol's solution in endoscopic diagnosis of early esophageal cancer]

About 1500 high-risk subjects of esophageal cancer were found during screening by balloon cytology and all of them were examined endoscopically. Among them, 120 were considered as having early esophageal cancer and precancerous lesions. During the examination, Lugol's solution staining was used and guiding biopsy was taken. 98 subjects with unstained lesions were found, and biopsy showed early esophageal cancer in 60 (61.2%) and moderate and severe dysplasia in 38 (38.8%). It is usually extremely difficult to detect and localize the very early esophageal mucosal and submucosal carcinoma. But endoscopic examination and using Lugol's solution staining with multiple spots biopsy from unstained area are of great assistance. Minute malignant lesions may not be overlooked.

Phase analysis of bulk samples using sample-tilting X-ray diffractometry

In the Bragg–Brentano X-ray powder diffractometer, the sample-tilting X-ray diffraction (STD) technique probes a fixed depth of penetration from the sample surface. In this way, phase analysis can be carried out from the surface layers to the depth probed by the CBD (conventional Bragg–Brentano geometry X-ray diffraction) method. In the present paper, after derivation of the diffracted intensity and the observed crystal-plane azimuthal equations, attention is focused on investigations of the geometrical optics of X-ray surface reflection by comparing the STD and CBD methods. Some examples are given to illustrate the applications of the STD technique for solving phase analyses and related problems.