[Clinical analysis of corneal interface infection].

Objective: To analyze the clinical features of corneal interface infection. Methods: A retrospective case series study was conducted to explore the clinical features of interstitial corneal infection. The data of eight patients (eight eyes) who were diagnosed with interstitial corneal infection after undergoing corneal transplant or corneal refractive surgery and visited Beijing Tongren Eye Center from January to December 2018 were collected, including two male and six female patients aged between 18 and 55 years (median age, 27 years). The patients' general information, surgical type, onset time, and clinical manifestations were recorded. The lesions were examined by in vivo corneal laser confocal microscopy (IVCM), and microbial cultures and drug sensitivity tests were performed. Results: Among the 8 patients, 4 had undergone small-incision lenticule extraction (SMILE), 2 had undergone lamellar keratoplasty, and 2 had undergone endothelial keratoplasty. The onset of infection occurred between 2 and 30 days after surgery, with a mean of 9.8 days. Among the 3 patients who had undergone SMILE, the treatment outcome was corneal haze or opacity, while the remaining 5 cases required corneal transplantation for interstitial infections. The pathogens of the 4 cases of interstitial infection after corneal transplantation were all Candida species. Under the IVCM, patients with corneal interstitial bacterial infections showed a large amount of necrotic tissue with no normal tissue structure in the corneal stroma, with infiltration of inflammatory cells and local aggregation of inflammatory cells, but no typical pathogen was observed. Patients with fungal infections showed fungal hyphae under the corneal cap (filamentous fungal infection) or dense, punctate, high-reflection structures in the corneal interstitial space (yeast-like fungal infection). Conclusions: Corneal interlayer infection is difficult to diagnose early and has a poor prognosis. IVCM can assist in early diagnosis. The pathogen spectrum of corneal interlayer infection may differ from that of corneal infection caused by trauma.

[Analysis of clinical manifestations and imaging characteristics of in vivo confocal microscopy for Nocardia keratitis].

Objective: To analyze the clinical manifestations and imaging characteristics of in vivo confocal microscopy (IVCM) for Nocardia keratitis. Methods: It was a retrospective case series study. Medical records of 16 consecutive patients (16 eyes) with Nocardia keratitis were collected from the Department of Ophthalmology at Beijing Tongren Hospital, Capital Medical University between 2018 and 2022. The group consisted of 11 males and 5 females. The inclusion criteria for the study were the presence of typical clinical manifestations of Nocardia keratitis and at least one positive pathogenic test (corneal scraping or microbial culture) indicating Nocardia infection. The medical history, clinical and microbiological examination data of the patients were analyzed, including risk factors, diagnosis time, clinical manifestations, diagnostic methods, strain isolation, cure time, and best corrected visual acuity before and after treatment. This study utilized techniques such as slit lamp microscopy, in vivo confocal microscopy (IVCM), scraping cytology, microbial culture, and mass spectrometry identification. Results: The main risk factors for Nocardia keratitis included plant or foreign body injuries (5 out of 16 cases), contact lens use (4 out of 16 cases), and surgery (2 out of 16 cases). The average time to diagnosis was (20.8±11.8) days, with the shortest time being 8 days and the longest being 60 days. The best corrected visual acuity was less than 0.05 in 7 patients, between 0.05 to 0.3 in 7 patients, and greater than or equal to 0.3 in 2 patients. The typical symptoms included superficial gray-white infiltration in a wreath-like pattern on the cornea, corneal ulcers with dry and gray-white necrotic tissue coverage, and in severe cases, corneal ulcer perforation. Nocardia corneal infection was identified in 12 out of 16 cases by scraping cytology, 9 out of 16 cases by mass spectrometry, and 8 out of 16 cases by both methods. IVCM showed the presence of fine and moderately reflective filamentous hyphae in the subepithelial and superficial stromal layer of the cornea, arranged in elongated, beaded, and branched structures. Infiltration of many hyper-reflective round inflammatory cells was also seen around the hyphae. Fourteen cases were treated with medication and 2 cases were treated with corneal transplantation. The average cure time was (37.5±25.2) days and there were no cases of recurrence during the follow-up period (all greater than 6 months). Conclusions: Nocardia keratitis is primarily characterized by dense, round, or wreath-like infiltration in the early stage, and by gray-white dry necrotic secretion and hypopyon on the surface of corneal ulcers in the middle and late stages. Fine, branched or beaded, and moderately reflective filamentous structures are the hallmark of the corneal lesion on the IVCM images.

[Efficacy of radial shock wave guided by soft tissue surgery theory in the treatment of lateral epicondylitis].

Objective: To explore the efficacy of radial shock wave therapy (RSWT) for lateral epicondylitis (LE). Methods: A total of 54 cases suffering from LE from Department of Pain Medicine of Fujian Provincial Hospital between December 2017 to October 2019 were randomly assigned to experimental group (n=27) and control group (n=27). Subjects in the experimental group were applied with RSWT in the lateral elbow area plus scapular back area, while patients in control group were applied with RSWT only in the lateral elbow area. Patients in both groups underwent RSWT one session per week for four weeks. Numeric rating scale (NRS), pain-free grip (PFG) test and patient-rated tennis elbow evaluation (PRTEE) in both groups were evaluated and compared at the pre-treatment, one week, one month and three months after treatment. Results: The NRS scores at pre-treatment, one week, one month and three months after treatment in experimental group were 6.5±1.6, 4.0±1.1, 3.9±1.5, 1.7±1.1, respectively, while those in control group were 6.2±1.4, 3.8±1.3, 4.2±1.2, 2.6±1.2, respectively. Compared with those at pre-treatment, the NRS scores in both groups were significantly decreased at one week, one month and three months after treatment (all P<0.05). The PRTEE and PFG results showed significant improvement after treatment (all P<0.05). The NRS scores and PRTEE at three months after treatment in the experimental group were 18±11, 1.7±1.1, respectively, which were significantly lower than those in the control group (25±11, 2.6±1.2, respectively) (both P<0.05). Conclusions: RSWT exerts a beneficial effect on LE. Guided by the soft tissue surgery theory, RSWT in the lateral elbow area plus scapular back area produces better pain reduction and functional improvement compared with RSWT only in the lateral elbow area.

[Potential pleiotropism of cancer-related single nucleotide polymorphisms among Chinese population].

Objective: To investigate the potential pleiotropism of cancer-related single nucleotide polymorphisms (SNPs) among Chinese population. Methods: Based on the catalogue of GWAS jointly constructed by the National Human Genome Research Institute and the European Institute of Bioinformatics, according to population origin (Chinese population and non-Chinese population) and disease traits (cancer and non-cancer traits). All SNPs found by GWAS before August 2020 were divided into four categories: cancer in Chinese population, non-cancer in Chinese population, cancer in non-Chinese population and non-cancer in non-Chinese population. The number, correlation and linkage of the four categories of SNPs were described. Results: By August 2020, a total of 196 813 SNPs from 4 096 GWAS were included in the GWAS directory. The information that SNPs refer to unknown or were not related to the disease was excluded, and 117 441 independent SNPs were finally included. There were 619 SNPs related to cancer and 9 569 SNPs related to non-cancer disease in Chinese population, respectively. There were 4 624 SNPs related to cancer and 106 448 SNPs related to non-cancer disease (trait) in non-Chinese population, respectively. Three SNPs, rs2736100, rs6983267 and rs401681, were associated with two or more types of cancer in both Chinese and non-Chinese populations. Seven SNPs, rs7705526, rs2736100, rs10993994, rs2735839, rs4430796, rs174537 and rs9271588, were associated with cancer and non-cancer diseases in both Chinese and non-Chinese populations, respectively. Conclusion: There is a potential pleiotropism of cancer-related SNPs in Chinese population.

A mutational signature associated with alcohol consumption and prognostically significantly mutated driver genes in esophageal squamous cell carcinoma.

Background: Esophageal squamous cell carcinoma (ESCC) is often diagnosed at an advanced and incurable stage. Information on driver genes and prognosticators in ESCC remains incomplete. The objective was to elucidate significantly mutated genes (SMGs), mutational signatures, and prognosticators in ESCC. Patients and methods: Three MutSig algorithms (i.e. MutSigCV, MutSigCL and MutSigFN) and '20/20+' ratio-metric were employed to identify SMGs. Nonnegative matrix factorization was used to decipher mutational signatures. Kaplan-Meier survival analysis, multivariate Cox and logistic regression models were applied to analyze association between mutational features and clinical parameters. Results: We identified 26 SMGs, including 8 novel (NAV3, TENM3, PTCH1, TGFBR2, RIPK4, PBRM1, USP8 and BAP1) and 18 that have been previously reported. Three mutational signatures were identified to be prevalent in ESCC including clocklike C>T at CpG, APOBEC overactive C>T at TpCp[A/T], and a signature featured by T>C substitution. The T>C mutational signature was significantly correlated with alcohol consumption (OR: 3.59; 95% CI: 2.30-5.67; P < 0.001). This alcohol consumption signature was also observed in liver cancer and head and neck squamous cell carcinoma, and its mutational activity was substantially higher in samples with mutations in TP53. Survival analysis revealed that TENM3 mutations (HR: 5.54; CI: 2.68-11.45; P < 0.001) and TP53 hotspot mutation p.R213* (HR: 3.37; CI: 1.73-8.06; P < 0.001) were significantly associated with shortened survival outcome. The association remained statistically significant after controlling for age, gender, TNM stage and tumor grade. Conclusions: We have uncovered several new SMGs in ESCC and defined an alcohol consumption related mutational signature. TENM3 mutations and the TP53 hotspot mutation p.R213* are independent prognosticators for poor survival in ESCC.

SOX2 gene expression and its role in triple negative breast cancer tissues.

The aim of this work was to study the expression of SOX2 gene in triple negative breast cancer and its role. One hundred and twenty specimens of paraffin-embedded triple negative breast cancer (TNBC) tissues were collected from Harbin Medical University Cancer Hospital, Heilongjiang, China between January 2014 and March 2018. The expression of SOX2 was detected using immunohistochemistry, and the relationship between the expression of SOX2 and clinical features was analyzed. Breast cancer cell lines (normal group, SOX2 interference group, SOX2 overexpression group) were cultured in vitro to detect the proliferation and cloning ability of the cell lines. The expression of SOX2 was related to lymph node metastasis and stage of breast cancer (P less than 0.05), but was not related to age, menopause or tumor size (P > 0.05); the expression of SOX2 in the overexpression group was significantly greater than that in the normal group after 72 hours, and no significant difference between the overexpression group and the interference group was observed. The number of clone cells with a diameter of 0.5 mm in the interference group was lower compared to the normal group, and that of the overexpression group was higher, but not significant. SOX2 is associated with the high invasiveness of breast cancer and can be used as a therapeutic target to inhibit the metastasis of cancer cells. SOX2 can promote the proliferation of breast cancer cells and affect the size of clone cells in its involvement in clone.

[Effect analysis of sequential laser application in treating the hypertrophic scars of burn children at early stage].

Objective: To explore the effects of sequential application of intensive pulsed light and carbon dioxide laser in treating the hypertrophic scars of burn children at early stage. Methods: A retrospective cohort before-after control study in the same patients was conducted. From January 2016 to December 2018, 145 burn children with hypertrophic scar at the early stage who met the inclusion criteria were admitted to the First Hospital of Jilin University, including 82 males and 63 females, aged 1 to 12 (3 (2, 6)) years. All the children were firstly treated with intense pulsed light therapy (no anesthesia or intravenous-inhalation combined anesthesia) at an interval of once per month, and then changed to carbon dioxide laser therapy (topical anesthesia or intravenous-inhalation combined anesthesia) when the degree of scar hyperemia was reduced, at an interval of once every 3 months, for a total of 3 times. Before the first intense pulsed light treatment (hereinafter referred to as before the first treatment) and 3 months after the last carbon dioxide laser treatment (hereinafter referred to as after the last treatment), scar scoring was evaluated by Vancouver Scar Scale (VSS), and scar hyperemia (denoted as hemoglobin level) was measured with Antera 3D® camera. The times of intense pulsed light, the time of single treatment, the anesthesia method, and the time of intravenous-inhalation combined anesthesia of intense pulsed light and carbon dioxide laser treatment were analyzed. After the last treatment, Likert Scale was used to evaluate the efficacy satisfaction of both doctors and patients. Adverse reactions were recorded during the treatment. Data were statistically analyzed with Wilcoxon signed rank sum test, and paired sample t test. Results: The color, vascular distribution, thickness, and softness scores, and total score in VSS scoring of scars of children after the last treatment were significantly lower than those before the first treatment (Z=-6.05, -10.34, -9.84, -9.28, -10.43, P<0.01). The hemoglobin level of scar of children after the last treatment was 1.86±0.24, significantly lower than 2.27±0.32 before the first treatment (t=17.65, P<0.01). A total of 411 times of intense pulsed light therapy were performed, (2.8±0.6) times per person, and the single treatment time was 35 (20, 45) s. There were 392 times (95.38%) without anesthesia, and 19 times (4.62%) with intravenous-inhalation combined anesthesia with time of 6 (5, 8) min. The single treatment time of carbon dioxide laser therapy was 5 (3, 10) min. There were 364 times (83.68%) of topical anesthesia and 71 times (16.32%) of intravenous-inhalation combined anesthesia with time of 10 (8, 15) min. After the last treatment, the efficacy satisfaction scores of doctors and patients were (4.3±0.7) and (3.8±1.0) points, respectively. Blisters occurred in 5 cases after intense pulsed light treatment, which were healed naturally after drainage. One child developed local skin infection, skin redness and swelling accompanied by purulent exudate after carbon dioxide laser treatment, which was improved after skin disinfection and external use of mupirocin ointment. No inflammatory pigmentation, worsening of hyperplasia of scar, erythema, or other skin adverse reactions or anesthetics-related adverse reactions occurred in any child. Conclusions: Sequential application of intense pulsed light and carbon dioxide laser to treat the hypertrophic scars of burn children at early stage can obviously improve the appearance and texture of scar, with higher satisfaction of doctors and patients and fewer adverse reactions.

[Application values of genome-wide association studies in screening for breast cancer].

Objective: To investigate the potential application values of screening on breast cancer, using the single-nucleotide polymorphisms (SNPs) that were identified from the genome- wide association studies (GWASs). Methods: Two million Chinese women aged 35-69 years were simulated, based on both age distributions, age-specific incidence rates of breast cancer and the distribution of known risk factors, in 2013. Twenty-three SNPs identified from GWAS were further simulated. Both genetic-related risks explained by each SNPs and the improvement on the risks under reclassification, were used to select SNPs for the prediction on breast cancer among the targeted high-risk population. Further analyses were conducted to investigate the following items as: improvements on detection rates of breast cancer among the high-risk populations, areas under the curve (AUC) and the odds ratio (OR) among women at high risk. Results: A total of 12 SNPs were eligible for targeting the high-risk population of breast cancer. When high-risk populations were defined as women whose predicted risks were higher than the 95(th) predicted risk of the whole population, the detection rate (146.99/100 000) among high-risked women predicted by 12 SNPs would be significantly lower than 177.46/100 000, which was predicted by the known risk factors (P<0.001), among the high-risked women. Among those women at high risk, the detection rate (229.00/100 000) predicted by integrating known risk factors and 12 SNPs was significantly higher than that predicted by known risk factors (P<0.001). Also, the AUC increased from 64.4% to 67.8% (P<0.001), and the OR of increased from 3.32 to 4.33, predicted by integrating known risk factors and 12 SNPs, for women at high risk on breast cancer. Conclusion: Targeted SNPs that were identified from genome- wide association studies could be used to improve the detection rates as well as the overall accuracy of risk prediction so as to identify the potential high-risk women on breast cancer before carrying on the screening program.

Near-Term Decrease in Brain Volume following Mild Traumatic Injury Is Detectible in the Context of Preinjury Volumetric Stability: Neurobiologic Insights from Analysis of Historical Imaging Examinations.

BACKGROUND AND PURPOSE: Neurodegeneration after mild traumatic brain injury may manifest as decreasing regional brain volume that evolves from months to years following mild traumatic brain injury and is associated with worse clinical outcomes. We hypothesized that quantitative brain volume derived from CT of the head, performed for clinical indications during routine care, would change with time and provide insights into the putative neuroinflammatory response to mild traumatic brain injury. MATERIALS AND METHODS: We searched the electronic medical record of our institution for NCCTs of the head performed in patients with mild traumatic brain injury and included those who also underwent NCCTs of the head 1 month to 1 year before and after mild traumatic brain injury for an indication unrelated to trauma. Controls underwent 3 sequential NCCTs of the head with indications unrelated to trauma. The whole-brain and intracranial volume groups were computed using ITK-SNAP. Brain volumes normalized to intracranial volumes were compared across time points using the Wilcoxon signed-rank test. RESULTS: We identified 48 patients from 2005 to 2015 who underwent NCCTs of the head in the emergency department for mild traumatic brain injury and had NCCTs of the head performed both before and after mild traumatic brain injury. Median normalized brain volumes significantly decreased on the follow-up study post-mild traumatic brain injury (0.86 versus 0.84, P < .001) and were similar compared with pre-mild traumatic brain injury studies (0.87 versus 0.86, P = .927). There was no significant difference between normalized brain volumes in the 48 controls. CONCLUSIONS: A decrease in brain volume following mild traumatic brain injury is detectable on CT and is not seen in similar patients with non-mild traumatic brain injury during a similar timeframe. Given the stability of brain volume before mild traumatic brain injury, CT volume loss may represent the subtle effects of neurodegeneration.

[Overdiagnosis in mammography screening for breast cancer].

Screening has been always considered as a double-edged sword. Cancer screening could save lives in some cases, however, in other cases, it might also turn people into overdiagnosis. Overdiagnosis is the diagnosis of cancer that will never cause symptoms or death during a patient's lifetime. Therefore, overdiagnosis might lead to unnecessary treatments and lifetime surveillance, and then increase economic burden and psychological burden. In this review, we focus on how to correctly evaluate the overdiagnosis rate, and how to avoid or reduce the harms caused by overdiagnosis in the future according to the reasons associated with overdiagnosis. After systematically reviewing the previous studies, we will try to identify the potential reasons associated with overdiagnosis in breast cancer screening with mammography, address how to correctly evaluate the overdiagnosis rate, and finally provide some suggestions to reduce the overdiagnosis.

Groove selectivity in the interaction of 9-aminoacridine-4-carboxamide antitumor agents with DNA.

Theoretical quantitative evaluation of the intercalative binding to DNA of the new antitumor drug 9-aminoacridine-4-carboxamide indicates that, in contradiction with a recently proposed model, the compound should show specificity for interaction with the major (and not minor) groove of GC sequences.

Modelling basic features of specificity in DNA-aureolic acid-derived antibiotic interactions.

The nonintercalative groove binding of a simplified model of olivomycin, to sequences d(CGCGCGC)2, d(TATATAT)2, and d(CICICIC)2 is investigated. A significant preference is displayed for the minor groove of the d(CG) sequence. This is due predominantly to the formation of H-bonds between the hydroxyl groups on the aglycone of the drug and the 2-amino group of the central guanine of the oligonucleotide.

An enantioselective total synthesis of (+)-geissoschizine.

[formula: see text] A concise asymmetric synthesis of the indole alkaloid (+)-geissoschizine (1) has been completed. The synthesis features the highly diastereoselective vinylogous Mannich reaction of 3 with 4 to give 5, which is elaborated into the key tetracyclic intermediate 7 in two steps. Following the stereoselective introduction of the ethylidene moiety to give 9, reduction of the lactam and radical decarboxylation via an acyl selenide gave 12, which was converted into (+)-geissoschizine by formylation. The synthesis requires only 11 chemical operations and proceeds in an overall yield of 17%.

Twenty-year trends of primary liver cancer incidence rates in an urban Chinese population.

The objective of this study was to describe trends in the incidence rates of primary liver cancer in a geographically defined Chinese population. Primary liver cancer cases (N=13 685) were diagnosed between 1981 and 2000 and identified by the Tianjin Cancer Registry. Age-adjusted and age-specific incidence rates were examined in both males and females. Poisson regression was employed to assess the incidence rate trends. Crude and age-adjusted incidence rates in the study period were: 27.4/100 000 and 16.4/100 000 in males and 11.5/100 000 and 6.4/100 000 in females, respectively. While the results from Poisson regression analyses suggest statistically significant trends of declining incidence rates of primary liver cancer overall, trends were not consistent across age and sex groups. The decline in incidence was observed, for the most part, in the 40-69 age group, with a greater decrease in males. Our findings provide a new evidence of a downward trend in incidence rates of this disease in China for a period of 20 years. As the observed decline is relatively small and inconsistent across sex and age groups, a continued epidemiological observation on this condition is required.

A theoretical investigation on the sequence selective binding of daunomycin to double-stranded polynucleotides.

Theoretical computations are performed on the structural and energetical factors involved in the sequence selective binding of daunomycin (DNM) to six representative self-complementary double-stranded hexanucleotides: d(CGTACG)2,d(CGATCG)2,d(CITACI)2, d(TATATA)2, d(CGCGCG)2 and d(TACGTA)2. The conformational angles of the hexanucleotides are fixed in values found in the representative crystal structure of the d(CGTACG)2-DNM complex. The intermolecular DNM-hexanucleotide interaction energies and the conformational energy changes of DNM upon binding are computed and optimized in the framework of the SIBFA procedure, which uses empirical formulas based on ab initio SCF computations. Among the two regularly alternating hexanucleotides, d(TATATA)2 and d(CGCGCG)2, a stronger binding is predicted for the former, in agreement with experimental results obtained with poly(dA-dT).poly(dA-dT) and poly(dG-dC).poly(dG-dC). Altogether, however, among the six investigated sequences, the strongest complexes are computed for the mixed hexanucleotides d(CGATCG)2 and d(CGTACG)2, containing the intercalation site between two CG base pairs and an adjacent TA base pair. This situation may be related to the increased affinity of DNM for GC rich DNA's and to the situation in the crystal structure of the DNM-d(CGTACG)2 complex. Analysis of the intrinsic base sequence preferences expressed by the individual constituents of DNM, namely the daunosamine side chain, the chromophore ring and its two 9-hydroxyl and 9-acetoxy substituents, reveals that the overall sequence preference found is the result of a rather intricate interplay of intrinsic sequence preferences, in particular at the level of daunosamine and the 9-hydroxyl substituent.(ABSTRACT TRUNCATED AT 250 WORDS)

The SARS outbreak in a general hospital in Tianjin, China -- the case of super-spreader.

Severe acute respiratory syndrome (SARS) is a newly emerged infectious disease with a high case-fatality rate and devastating socio-economic impact. In this report we summarized the results from an epidemiological investigation of a SARS outbreak in a hospital in Tianjin, between April and May 2003. We collected epidemiological and clinical data on 111 suspect and probable cases of SARS associated with the outbreak. Transmission chain and outbreak clusters were investigated. The outbreak was single sourced and had eight clusters. All SARS cases in the hospital were traced to a single patient who directly infected 33 people. The patients ranged from 16 to 82 years of age (mean age 38.5 years); 38.7% were men. The overall case fatality in the SARS outbreak was 11.7% (13/111). The outbreak lasted around 4 weeks after the index case was identified. SARS is a highly contagious condition associated with substantial case fatality; an outbreak can result from one patient in a relatively short period. However, stringent public health measures seemed to be effective in breaking the disease transmission chain.

A theoretical investigation on the sequence selective binding of mitoxantrone to double-stranded tetranucleotides.

Theoretical computations are performed on the comparative binding energetics of mitoxantrone (MX), a newly synthesized intercalating anthraquinone antitumor drug, to six representative double-stranded tetranucleotides: d(GCGC)2, d(CGCG)2, d(ATAT)2, d(TATA)2, d(GTGT), d(ACAC), and d(CCGG)2. The computations are performed with the SIBFA procedure, which uses empirical formulas based on ab initio SCF computations. The best binding configuration of mitoxantrone locates its two side chains in the major groove. A considerable preference is elicited for intercalation of the chromophore ring in a pyrimidine (3'-5') purine sequence rather than the isomeric purine (3'-5') pyrimidine sequence. Contrary to the situation encountered with "simple" intercalators, in which this preference is generally attributed solely to differences in the energies of unstacking necessary to generate the intercalation sites, the preference is dictated in MX to a large extent by the intermolecular interaction energy term. This result is imposed by the interactions of the side chains of MX with the oligonucleotide.

A theoretical study of the comparative binding affinities of daunomycin derivatives to a double-stranded oligomeric DNA. Proposal for new high affinity derivatives.

Theoretical computations were performed on the comparative binding affinities of daunomycin (DM, 1) and seven derivatives related to the double-stranded oligonucleotide d(CGATCG)2. The compounds investigated were 4-demethoxy DM (2), and its beta-anomer (3), 4-demethoxy-7,9-bis-epi DM (4) and its beta anomer (5), a derivative with glucosamine instead of daunosamine (6), and two additional hypothetical DM derivatives in which the cationic NH3+ group of the daunosamine moiety is replaced by either a CH2--NH3+ group (7) or a CH2CH2NH3+ group (8), so as to indicate the effect on the binding affinity of interposing one- or two-methylene groups between the sugar and the cationic charge. The conformational angles of the hexanucleotide are fixed in values found in the representative crystal structure of the d(CGTACG)2-DM complex. The intermolecular drug-hexanucleotide interaction energies and the conformational energy changes of the drug upon binding are computed and optimized in the framework of the SIBFA procedure (sum of interactions between fragments computed ab initio), which uses empirical formulas based on ab initio SCF computations. The overall binding affinity ordering of compounds 1-6 compares satisfactorily with the ordering of available experimental affinity constants. The binding affinities of compounds 7 and 8, for which no experimental results seem to be available yet, are predicted to be significantly higher than those of the parent compound DM, with the greatest affinity found for 7. Because of the overall correlation between binding affinity of anthracyclines to DNA and their antitumor activity, these last two compounds deserve an exploration of their chemotherapeutic efficiency.