White spot lesion-related perception of aesthetics and treatment satisfaction among orthodontic patients, orthodontists and other dental specialists.

OBJECTIVE: To investigate the impact of various degrees of white spot lesions (WSLs) of maxillary anterior teeth on the aesthetic perception and treatment satisfaction among orthodontic patients, orthodontists and other dental specialists and to evaluate the differences among the three groups. METHODS: A total of 45 orthodontic patients (OP), 45 orthodontists (OR) and 45 other dental specialists (OS) were recruited. Subjective evaluations of perceived aesthetics and treatment satisfaction were performed towards eight digitally generated photographs of maxillary anterior teeth with incremental degrees of WSLs using a numerical visual analogue scale (VAS) from 0 to 100. Data were collected and analysed with descriptive statistics, repeated one-way analysis of variance and multivariable generalized estimating equations. RESULTS: A total of 135 valid questionnaires were collected. Regarding aesthetic scores for WSLs, OP gave more positive scores than OR and OS (p < .05) towards excessive white spot formation without colouration and were more tolerant than OR (p < .05) towards excessive white spot formation with slight colouration. The level of treatment satisfaction for slight to severe WSLs without cavitation was higher in OP than OR. Patients with higher education levels had more negative scores for aesthetic perception and treatment satisfaction (p < .05). Patients who brushed teeth more frequently scored lower in treatment satisfaction (p < .05). CONCLUSIONS: Orthodontists were the most critical when evaluating aesthetics and treatment satisfaction for slight to severe WSLs without cavitation. For orthodontic patients, better oral hygiene habits and higher education levels were associated with more critical attitudes towards WSLs.

The LiV3O8 Superlattice Cathode with Optimized Zinc Ion Insertion Chemistry for High Mass-Loading Aqueous Zinc-Ion Batteries.

Resolving the sluggish transport kinetics of divalent Zn2+ in the cathode lattice and improving mass-loading performance are crucial for advancing the zinc-ion batteries (AZIBs) application. Herein, PEO-LiV3O8 superlattice nanosheets (PEO-LVO) with expanded interlayer spacing (1.16 nm) are fabricated to provide a high-rate, stable lifetime, and large mass-loading cathode. The steady in-plane expansion without shrinkage after the first cycle, but reversible H+/Zn2+ co-insertion in PEO-LVO are demonstrated by operando synchrotron X-ray diffraction and ex situ characterizations. Moreover, the large capacity of PEO-LVO is traced back to the optimized Zn2+ insertion chemistry with increased Zn2+ storage ratio, which is facilitated by the interlayer PEO in lowering the Zn2+ diffusion barrier and increased number of active sites from additional interfaces, as anticipated by density functional theory. Due to the optimized ion insertion resulting in stalled interfacial byproducts and rapid kinetics, PEO-LVO achieves excellent high mass-loading performance (areal capacity up to 6.18 mAh cm-2 for freestanding electrode with 24 mg cm-2 mass-loading and 2.8 mAh cm-2 at 130 mA cm-2 for conventional electrode with 27 mg cm-2 mass-loading). As a proof-of-concept, the flexible all-solid-state fiber-shaped AZIBs with high mass-loading woven into a fabric can power an electronic watch, highlighting the application potential of PEO-LVO cathode.

THE USE OF DENTAL PATIENT-REPORTED OUTCOMES AMONG COMPARATIVE OBSERVATIONAL STUDIES IN ORTHODONTICS: A METHODOLOGICAL STUDY.

OBJECTIVE: To identify and summarize the presence and characteristics of dental patient-reported outcomes (dPROs) and dental patient-reported outcome measures (dPROMs) within comparative observational studies published in 5 leading orthodontic journals. METHODS: Electronic searching was performed to identify intervention (therapeutic or preventive) related comparative observational studies published in selected journals between 2015 and 2021. Two authors extracted the characteristics of each included study independently and in duplicate and summarized the dPROs and dPROMs used in these studies. All dPROs were classified into 2 general types (oral health-related quality of life [OHRQoL] and others), while dPROMs were divided into 3 categories (single-item questionnaires, generic multiple-item questionnaires, and specific multiple-item questionnaires). In addition, dPROMs were examined, if they evaluated the 4 dimensions of OHRQoL (oral function, orofacial pain, orofacial appearance, and psychosocial impact). RESULTS: A total of 683 observational studies were eligible and included of which 117 (17.1%) used dPROs and dPROMs. Seven different dPROs (OHRQoL, patients' satisfaction with treatment, preferences, concerns, compliance, duration, and unwanted events) and 33 different dPROMs (including 8 single-item questionnaires, 11 generic multiple-item questionnaires, and 14 specific multiple-item questionnaires) were identified in these studies. OHRQoL was the most commonly used dPRO (92/117, 78.6%), while Oral Health Impact Profile 14 (OHIP-14) was the most frequently used dPROM (20/92, 21.7%). In terms of study design, cross-sectional studies had the highest proportion of dPRO usage (62/148, 41.9%), followed by cohort studies (63/505, 12.5%) and case-control studies (1/30, 3.3%). CONCLUSIONS: Only one-sixth of comparative observational studies published in leading orthodontic journals could reflect patients' perspectives. Observational studies in orthodontics need to provide more patient-important information through the use of dPROs and dPROMs.

Group 1 innate lymphoid cell activation via recognition of NKG2D and liver resident macrophage MULT-1: Collaborated roles in triptolide induced hepatic immunotoxicity in mice.

Triptolide (TP) is the major bioactive component of traditional Chinese medicine Tripterygium wilfordii Hook. F., a traditional Chinese medicinal plant categorized within the Tripterygium genus of the Celastraceae family. It is recognized for its therapeutic potential in addressing a multitude of diseases. Nonetheless, TP is known to exhibit multi-organ toxicity, notably hepatotoxicity, which poses a significant concern for the well-being of patients undergoing treatment. The precise mechanisms responsible for TP-induced hepatotoxicity remain unresolved. In our previous investigation, it was determined that TP induces heightened hepatic responsiveness to exogenous lipopolysaccharide (LPS). Additionally, natural killer (NK) cells were identified as a crucial effector responsible for mediating hepatocellular damage in this context. However, associated activating receptors and the underlying mechanisms governing NK cell represented innate lymphoid cell (ILC) activation remained subjects of inquiry and were not yet investigated. Herein, activating receptor Killer cell lectin like receptor K1 (NKG2D) of group 1 ILCs was specifically upregulated in TP- and LPS-induced acute liver failure (ALF), and in vivo blockade of NKG2D significantly reduced group 1 ILC mediated cytotoxicity and mitigated TP- and LPS-induced ALF. NKG2D ligand UL16-binding protein-like transcript 1 (MULT-1) was found upregulated in liver resident macrophages (LRMs) after TP administration, and LRMs did exhibit NK cell activating effect. Furthermore, M1 polarization of LRMs cells was observed, along with an elevation in intracellular tumor necrosis factor (TNF)-α levels. In vivo neutralization of TNF-α significantly alleviated TP- and LPS-induced ALF. In conclusion, the collaborative role of group 1 ILCs and LRMs in mediating hepatotoxicity was confirmed in TP- and LPS-induced ALF. TP-induced MULT-1 expression in LRMs was the crucial mechanism in the activation of group 1 ILCs via MULT-1-NKG2D signal upon LPS stimulation, emphasizing the importance of infection control after TP administration.

Cation Defect-Engineered Boost Fast Kinetics of Two-Dimensional Topological Bi2 Se3 Cathode for High-Performance Aqueous Zn-Ion Batteries.

The challenge with aqueous zinc-ion batteries (ZIBs) lies in finding suitable cathode materials that can provide high capacity and fast kinetics. Herein, two-dimensional topological Bi2 Se3 with acceptable Bi-vacancies for ZIBs cathode (Cu-Bi2-x Se3 ) is constructed through one-step hydrothermal process accompanied by Cu heteroatom introduction. The cation-deficient Cu-Bi2-x Se3 nanosheets (≈4 nm) bring improved conductivity from large surface topological metal states contribution and enhanced bulk conductivity. Besides, the increased adsorption energy and reduced Zn2+ migration barrier demonstrated by density-functional theory (DFT) calculations illustrate the decreased Coulombic ion-lattice repulsion of Cu-Bi2-x Se3 . Therefore, Cu-Bi2-x Se3 exhibits both enhanced ion and electron transport capability, leading to more carrier reversible insertion proved by in situ synchrotron X-ray diffraction (SXRD). These features endow Cu-Bi2-x Se3 with sufficient specific capacity (320 mA h g-1 at 0.1 A g-1 ), high-rate performance (97 mA h g-1 at 10 A g-1 ), and reliable cycling stability (70 mA h g-1 at 10 A g-1 after 4000 cycles). Furthermore, quasi-solid-state fiber-shaped ZIBs employing the Cu-Bi2-x Se3 cathode demonstrate respectable performance and superior flexibility even under high mass loading. This work implements a conceptually innovative strategy represented by cation defect design in topological insulator cathode for achieving high-performance battery electrochemistry.

Triptolide leads to hepatic intolerance to exogenous lipopolysaccharide and natural-killer-cell mediated hepatocellular damage by inhibiting MHC class I molecules.

BACKGROUND: Tripterygium wilfordii Hook. F (TWHF) is used as a traditional Chinese medicine, called thunder god vine, based on its efficacy for treating inflammatory diseases. However, its hepatotoxicity has limited its clinical application. Triptolide (TP) is the major active and toxic component of TWHF. Previous studies reported that a toxic pretreatment dose of TP leads to hepatic intolerance to exogenous lipopolysaccharide (LPS) stimulation, and to acute liver failure, in mice, but the immune mechanisms of TP-sensitised hepatocytes and the TP-induced excessive immune response to LPS stimulation are unknown. PURPOSE: To identify both the key immune cell population and mechanism involved in TP-induced hepatic intolerance of exogenous LPS. STUDY DESIGN: In vitro and in vivo experiments were conducted to investigate the inhibitory signal of natural killer (NK) cells maintained in hepatocytes, and the ability of TP to impair that signal. METHODS: Flow cytometry was performed to determine NK cell activity and hepatocyte histocompatibility complex (MHC) class I molecules expression; the severity of liver injury was determined based on blood chemistry values, and drug- or cell-mediated hepatocellular damage, by measuring lactate dehydrogenase (LDH) release. In vivo H-2Kb transduction was carried out using an adeno-associated viral vector. RESULTS: Interferon (IFN)-γ-mediated necroptosis occurred in C57BL/6N mice treated with 500 µg TP/kg and 0.1 mg LPS/kg to induce fulminant hepatitis. Primary hepatocytes pretreated with TP were more prone to necroptosis when exposed to recombinant murine IFN-γ. In mice administered TP and LPS, the intracellular IFN-γ levels of NK cells increased significantly. Subsequent study confirmed that NK cells were activated and resulted in potent hepatocellular toxicity. In vivo and in vitro TP administration significantly inhibited MHC class I molecules in murine hepatocytes. An in vitro analysis demonstrated the susceptibility of TP-pretreated hepatocytes to NK-cell-mediated cytotoxicity, an effect that was significantly attenuated by the induction of hepatocyte MHC-I molecules by IFN-α. In vivo induction or overexpression of hepatocyte MHC-I also protected mouse liver against TP and LPS-induced injury. CONCLUSION: The TP-induced inhibition of hepatocyte MHC-I molecules expression leads to hepatic intolerance to exogenous LPS and NK-cell mediated cytotoxicity against self-hepatocytes. These findings shed light on the toxicity of traditional Chinese medicines administered for their immunomodulatory effects.

Depressed Symptomatology in Systemic Lupus Erythematosus Patients.

OBJECTIVE: Depression is a prevalent (24-30%) and significant comorbidity in patients with systemic lupus erythematosus (SLE). In the present study, we leveraged the longitudinal SLE cohort at the Washington University Lupus Clinic to address 1) what is the longitudinal course of depressed affect among outpatients with SLE and 2) what is the longitudinal relationship between SLE disease activity and depressed affect? METHODS: Longitudinal data from patients with American College of Rheumatology- or Systemic Lupus International Collaborating Clinics-classified SLE were analyzed. Depressed symptoms were assessed at each visit using the Center for Epidemiologic Studies Depression Scale, Revised (CESD-R), and SLE disease activity was measured via the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K). Group-based trajectory modeling (GBTM) and linear mixed models were used for analysis. RESULTS: The study sample (n = 144) was 56.3% Black and 38.9% White. GBTM revealed 5 distinct groups of patients who demonstrated consistent trends in depression over time. Members of groups 4 (n = 44, 30.6%) and 5 (n = 44, 30.6%) demonstrated CESD-R scores consistent with depression. Of note, Black patients were much more common in group 5 (n = 32, 72.7%, P < 0.02). Analyses identified an association between SLEDAI disease activity and depression scores in multivariate analysis but did not show significance in GBTM and univariate analysis. CONCLUSIONS: The majority (61.2%) of patients had CESD-R scores consistent with persistent depressed affect or major depression over a period of up to 4 years. The lack of a consistent relationship of CESD-R with SLE disease activity highlights the need to regularly monitor, treat, and better understand the causes behind this comorbidity.

Research progress on Mincle as a multifunctional receptor.

Macrophage-induced C-type lectin (Mincle), a lipopolysaccharide-induced protein, is widely expressed on antigen-presenting cells. Mincle acts as a pattern recognition receptor that recognizes pathogen-associated molecular patterns of pathogens such as bacteria and fungi, mainly glycolipids, which induces an acquired immune response against microbial infection. Interestingly, Mincle can also identify patterns of lipid damage-associated molecule patterns released by injured cells, such as Sin3-associated protein 130 and ß-glucosylceramides, which induces sterile inflammation and ultimately accelerates the progression of stroke, obesity, hepatitis, kidney injury, autoimmune diseases and tumors by promoting tissue inflammation. This article will review the various functions of Mincle, such as mediating sterile inflammation of tissues to accelerate disease progression, initiating immune responses to fight infection and promoting tumor progression.

Obeticholic acid aggravates liver injury by up-regulating the liver expression of osteopontin in obstructive cholestasis.

AIMS: Obeticholic acid (OCA) was approved for the treatment of primary biliary cholangitis (PBC) patients, as it can significantly improve the level of serum alkaline phosphatase. However, OCA-induced liver injury in PBC patients puts them at risk of acute chronic liver failure, thus limiting the clinical application of OCA. Osteopontin (OPN), an extracellular cell matrix molecule, is highly induced in many cholestatic liver diseases. Herein we explored whether liver injury exacerbation by OCA was related to OPN. MAIN METHODS: Bile duct ligation (BDL) mice were treated with OCA (40 mg/kg) to evaluate its effect on liver injury and OPN involvement. Enzyme-linked immunosorbent assay, western blot, immunohistochemistry, and other assays were used to detect OPN levels in serum and liver. Immunohistochemistry, and immunofluorescence, among other assays, were used to evaluate the extent of ductular reaction. The extent of fibrosis was also determined using various assays, such as immunohistochemistry, quantitative real-time PCR (qPCR), and hydroxyproline assays. KEY FINDINGS: OPN was overexpressed in the liver of BDL mice treated with OCA. OCA induced overexpression of OPN exacerbated ductular reaction, fibrosis, and liver inflammation, and reduced hepatocyte proliferation. SIGNIFICANCE: Upon liver injury, OCA upregulates the expression of OPN in the liver and accelerates disease progression. This mechanism helps explain the risk of liver damage associated with OCA.

Anxiety Symptoms Among Patients With Systemic Lupus Erythematosus Persist Over Time and Are Independent of SLE Disease Activity.

OBJECTIVE: The objectives of this study are to identify patterns of anxiety symptomology over time among patients with systemic lupus erythematosus (SLE) and to assess the longitudinal relationship between SLE disease activity and anxiety symptomology. METHODS: Longitudinal data from 139 patients with American College of Rheumatology or Systemic Lupus International Collborating Clinic (SLICC)-classified SLE were analyzed. Anxiety symptomology was assessed using the Patient-Reported Outcomes Measurement Information System (PROMIS) Emotional Distress: Anxiety Short Form 8a. SLE disease activity was measured using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)-2000 (S2K) and S2K Responder Index 50 (S2K RI-50). Group-based trajectory modeling (GBTM) identified longitudinal trajectories of anxiety symptomology. The relationship between disease activity and anxiety over time was assessed using multilevel linear regressions. RESULTS: The mean patient age was 40.2 years (standard deviation [SD], 12.7); 90.6% were female, and 56.1% were of Black race. All patients had at least three PROMIS anxiety scores over an average of 30.9 months (SD, 13.0). GBTM identified four trajectories of anxiety symptomology, labeled as the following: low (LA), average (AA), moderate (MA), and high anxiety (HA). Black patients were 2.47 (95% confidence interval: 1.19-5.12) times as likely as White patients to be classified into the MA or HA groups compared with the LA or AA groups. On multivariable analysis, active SLE disease was not significantly associated with anxiety over time (P = 0.19). CONCLUSION: Anxiety trajectories remained stable over time, and racial differences in anxiety severity were observed. SLE disease activity was not longitudinally associated with anxiety after controlling for depression and other factors. Further understanding of the factors that contribute to the persistence of anxiety among individuals with SLE is necessary.

Lipopolysaccharide Accelerates Neuropilin-1 Protein Degradation by Activating the Large GTPase Dynamin-1 in Macrophages.

Neuropilin-1 (Nrp1) is highly expressed in macrophages and plays a critical role in acute and chronic inflammation-associated diseases, such as sepsis, type II diabetes, and metabolic syndrome. Therefore, it is of importance to understand the regulation of Nrp1. It is known that lipopolysaccharide (LPS) downregulates Nrp1 mRNA levels through the NF-κB signaling in macrophages. However, whether and how LPS regulates Nrp1 protein degradation remain unknown. Here, we show that LPS promotes Nrp1 protein decay through a lysosome-dependent manner. Liver kinase B1 (LKB1)-Rab7 does not mediate this process. However, the large GTPase dynamin-1 (Dyn1) but not Dyn2 is involved in LPS-accelerated Nrp1 degradation. Mechanistically, LPS activates Dyn1 by attenuating p-Dyn1 (Ser774) levels, implying increased Nrp1 endocytosis and consequent degradation. As a result, blocking Nrp1 degradation by Dyn1 siRNA attenuates LPS-induced inflammatory response. Collectively, our study shows that LPS promotes Nrp1 protein degradation via a Dyn1-dependent pathway, revealing a previously uncovered role of Dyn1 in LPS-promoted Nrp1 protein decay.

Research progress on the relationship between orthodontic treatment and the oral microbiome / 口腔疾病防治

@#With the deepening of research in oral microbiomics, an important relationship between changes in the oral microbiome and orthodontic treatment has been found. Orthodontic treatment will have an impact on the oral and systemic microbiome. The presence of oral appliances can change the quantity and quality of the oral microbiometo and increase the risk of oral and even systemic diseases in patients undergoing orthodontic treatment. Compared with fixed orthodontic treatment, clear aligners will not have a harmful impact on the structure of the oral microbiome, which is more conducive to maintain oral health during the orthodontic treatment process. In addition, different bracket types and materials can lead to different changes in the oral microbiome, and the occurrence and development of orthodontic-related diseases, such as white spot lesions, dental caries, gingivitis and periodontitis, are also related to changes in the oral microbiome. At present, the role of the oral microbiome in the process of orthodontic treatment needs to be further studied. Whether a change in the oral microbiome caused by orthodontic treatment can be restored after orthodontic treatment is still uncertain and needs more research. This paper reviews the research progress on the application of microbiomics in orthodontics, including the impact of fixed appliances and clear aligners on the microbiome and the relationship between orthodontic-related diseases and the oral microbiome.

Development and validation of lupus nephritis case definitions using United States veterans affairs electronic health records.

OBJECTIVE: International Classification of Diseases (ICD) codes are commonly used to identify patients with rare diseases in electronic health records (EHRs). However, misclassification is common, impacting the validity of study results. In this study, we compared the accuracies of several ICD-based case definitions of lupus nephritis (LN) in identifying United States veterans with LN. METHODS: Using the Department of Veterans Affairs (VA) EHR, we identified all veterans with ≥1 ICD-9 or 10 diagnostic codes for systemic lupus erythematosus (SLE) between October 1, 1999 and September 30, 2017. A cohort was randomly selected for diagnostic validation and 9 ICD-based LN case definitions were applied to this cohort. The diagnostic accuracy of each definition was assessed against gold standard criterion of biopsy-proven LN. RESULTS: 18,420 veterans had ≥1 ICD-9 or 10 diagnostic codes for SLE; 981 were randomly selected for diagnostic validation. 95 veterans (9.7%) had biopsy-proven LN. The case definitions had high specificity and NPV but variable sensitivity and PPV. The definition containing ≥2 ICD -9 codes for SLE and ≥2 nephritis indicators had the highest combination of sensitivity and specificity (87.4% and 94.6% respectively). ICD-10 code for LN had high specificity (99.8%) and PPV (93.9%). CONCLUSION: ICD-based case definitions of LN in the VA population have high specificity and NPV but variable sensitivity and PPV. Our results may help guide the design of future LN studies in VA cohorts. The choice of specific case definitions depends on the relative importance of different accuracy measures to individual studies.

Methotrexate improves perivascular adipose tissue/endothelial dysfunction via activation of AMPK/eNOS pathway.

Adipose and endothelial dysfunction is associated with cardiovascular disease. Perivascular adipose tissue (PVAT) directly surrounds vessels and influences vessel function via a paracrine effect, and adenosine monophosphate (AMP)-activated protein kinase (AMPK) modulates the metabolic pathway, thus, the present study hypothesized that activation of AMPK in PVAT may regulate endothelial function in pathological settings. The present study investigated the effect of methotrexate (MTX) on adipocytokine expression in PVAT with an emphasis on the regulation of endothelial function. The effects of MTX and the mechanisms involved were investigated using a relaxation assay and western blot analysis. Reverse transcription­quantitative polymerase chain reaction and western blotting were used to detect the mRNA and protein expression levels. ELISA assay was used to quantify the level of TNF­α and IL­6. Palmitic acid (PA) stimulation induced inflammation and dysregulation of adipocytokine expression in PVAT. MTX treatment inhibited nuclear factor­κB p65 phosphorylation and downregulated expression of pro­inflammatory cytokines, including tumor necrosis factor­α and interleukin-6, whereas adiponectin expression increased. MTX increased AMPK phosphorylation under basal and inflammatory conditions in PVAT, whereas knockdown of AMPK via small interfering RNA diminished its modulatory effect, indicating that MTX inhibits inflammation in an AMPK­dependent manner. The present study prepared conditioned medium from PA­stimulated PVAT to induce endothelial dysfunction and observed that pre­treatment of PVAT with MTX effectively restored the loss of acetylcholine­induced vasodilation and increased endothelial nitric oxide synthase phosphorylation in the rat aorta. The results of the present study demonstrated that MTX ameliorated inflammation-associated adipocytokine dysregulation and thus prevented endothelial dysfunction. These data provide further pharmacological evidence regarding the beneficial effects of MTX in cardiovascular diseases.

Preparation and characterization of flexible nanoliposomes loaded with daptomycin, a novel antibiotic, for topical skin therapy.

The purpose of this study was to investigate flexible nanoliposomes for mediating topical delivery of daptomycin, and to document permeation rates and bacteriostatic activity towards skin infections. Response surface methodology was used to optimize the daptomycin-loaded flexible nanoliposomes (DAP-FL), and the amount of drug loaded into the particles was evaluated as the investigation index. The optimal lipid ratio was lecithin to sodium cholate 17:1 (w/w) and the lipid to drug ratio was 14:1 (w/w). The hydration temperature was set at 37°C and the duration of treatment with ultrasound was 20 minutes. The DAP-FL obtained had a small mean particle size (55.4 nm) with a narrow size distribution (polydispersity index 0.15). The mean entrapment efficiency was 87.85% ± 2.15% and the mean percent drug loading was 5.61% ± 0.14%. Using skin mounted between the donor and receptor compartments of a modified Franz diffusion cell, the percentage and quantity of cumulative daptomycin permeation from DAP-FL within 12 hours were measured at 96.28% ± 0.70% and (132.23 ± 17.73) µg/cm(2) *5 = 661.15 ± 88.65 µg/cm(2), directly, showing rapid and efficient antibacterial activity against Staphylococcus aureus. Following local administration of DAP-FL, daptomycin was detected in multilayer tissues within the skin and underlying structures in the dorsal skin of the mouse. Effective therapeutic concentrations were maintained for several hours, and significantly inhibited bacterial growth and injury-induced biofilms. These results demonstrate that the DAP-FL can enhance the ability of daptomycin to permeate the skin efficiently, where it has a powerful antibacterial action and activity against biofilms. This novel formulation of daptomycin has potential as a new approach in the clinical application of daptomycin.