Endoscopy-assisted latissimus dorsi muscle flap harvesting technique for immediate breast reconstruction

BACKGROUND

The purpose of this study is to investigate the usefulness of endoscopy-assisted latissimus dorsi muscle flap (LDMF) harvesting in immediate breast reconstruction following partial mastectomy.

MATERIALS AND METHODS

From November 2016 to December 2019, sixteen female breast cancer patients who underwent immediate breast reconstruction following partial mastectomy underwent LDMF harvesting with endoscopic assistance. This surgical technique was carried out with only one subaxillary skin incision without leaving a scar on the back. Patients' demographic characteristics, histopathologic factors, operative data, postoperative complications, and oncologic safety were collected through electronic chart review.

RESULTS

In sixteen patients, LDMFs were harvested successfully using an endoscopy-assisted technique without conversion to an open technique. The mean age of the patients was 48.0±8.0 years, and the mean body mass index was 24.4±3.9kg/m2. The most common histologic subtype was invasive ductal carcinoma, with a mean tumor size of 3.2±2.3cm. In terms of LDMF harvesting time, it took 168.4±44.0minutes. The most common postoperative complication, donor site seroma (75%), was managed non-surgically during the outpatient visit. In terms of cosmetic aspects, we've seen a high level of patient satisfaction, especially with scarring.

CONCLUSIONS

Endoscopy-assisted LDMF harvesting technique is safe and useful for breast reconstruction after partial mastectomy. Compared to the conventional open technique, this method does not leave a long scar on the donor site. As a result, it leads to better cosmetic outcomes and improves patient satisfaction.

Projection to extract the perpendicular component (PEPC) method for extracting kinetics from time-resolved data

Time-resolved x-ray liquidography (TRXL) is a potent method for investigating the structural dynamics of chemical and biological reactions in the liquid phase. It has enabled the extraction of detailed structural aspects of various dynamic processes, the molecular structures of intermediates, and kinetics of reactions across a wide range of systems, from small molecules to proteins and nanoparticles. Proper data analysis is key to extracting the information of the kinetics and structural dynamics of the studied system encrypted in the TRXL data. In typical TRXL data, the signals from solute scattering, solvent scattering, and solute-solvent cross scattering are mixed in the q-space, and the solute kinetics and solvent hydrodynamics are mixed in the time domain, thus complicating the data analysis. Various methods developed so far generally require prior knowledge of the molecular structures of candidate species involved in the reaction. Because such information is often unavailable, a typical data analysis often involves tedious trial and error. To remedy this situation, we have developed a method named projection to extract the perpendicular component (PEPC), capable of removing the contribution of solvent kinetics from TRXL data. The resulting data then contain only the solute kinetics, and, thus, the solute kinetics can be easily determined. Once the solute kinetics is determined, the subsequent data analysis to extract the structural information can be performed with drastically improved convenience. The application of the PEPC method is demonstrated with TRXL data from the photochemistry of two molecular systems: [Au(CN)₂^-]₃ in water and CHI₃ in cyclohexane.

Preoperative Chemoradiotherapy With Capecitabine With or Without Temozolomide in Patients With Locally Advanced Rectal Cancer: A Prospective, Randomised Phase II Study Stratified by O6-Methylguanine DNA Methyltransferase Status: KCSG-CO17-02

AIMS

To evaluate the clinical efficacy of adding temozolomide (TMZ) to preoperative capecitabine (CAP)-based chemoradiotherapy in patients with locally advanced rectal cancer (LARC) and validate O⁶-methylguanine DNA methyltransferase (MGMT) methylation status as a predictive marker for TMZ combined regimens.

MATERIALS AND METHODS

LARC patients with clinical stage II (cT3-4N0) or III (cT_anyN+) disease were enrolled. They were stratified into unmethylated MGMT (uMGMT) and methylated MGMT (mMGMT) groups by methylation-specific polymerase chain reaction before randomisation and were then randomly assigned (1:1) to one of four treatment arms: uMGMT/CAP (arm A), uMGMT/TMZ + CAP (arm B), mMGMT/CAP (arm C) and mMGMT/TMZ + CAP (arm D). The primary end point was the pathological complete response (pCR) rate.

RESULTS

Between November 2017 and July 2020, 64 patients were randomised. Slow accrual caused early study termination. After excluding four ineligible patients, 60 were included in the full analysis set. The pCR rate was 15.0% (9/60), 0%, 14.3%, 18.8% and 26.7% for the entire cohort, arms A, B, C and D, respectively (P = 0.0498 between arms A and D). The pCR rate was 9.7% in the CAP group (arms A + C), 20.7% in the TMZ + CAP group (arms B + D), 6.9% in the uMGMT group (arms A + B) and 22.6% in the mMGMT group (arms C + D). Grade 1-2 nausea or vomiting was significantly more frequent in the TMZ + CAP treatment groups (arms B + D) than in the CAP treatment groups (arms A + C, P < 0.001) with no difference in grade 3 adverse events. There were no grade 4 or 5 adverse events.

CONCLUSION

The addition of TMZ to CAP-based chemoradiotherapy tended to improve pCR rates, particularly in those with mMGMT LARC. MGMT status may warrant further investigation as a predictive biomarker for chemotherapeutic agents and radiotherapy.

PCSK9 modulates the Wnt/beta-catenin signaling pathway in myocardial ischemia/reperfusion injury

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein that affects cholesterol homeostasis. Recent research has found that PCSK9 has various effects on the heart that are unrelated to LDL cholesterol regulation. The Wnt/β-catenin signaling pathway plays a crucial role during heart development, and it is re-activated in response to cardiac injury. Low-density lipoprotein receptor-related proteins 5 (LRP5) act as co-receptors of Wnt ligands and are indispensable for Wnt/β-catenin signal transduction. However, it is not fully elucidated whether other members of the LDLR-superfamily may be targets of PCSK9.

Purpose

This study aimed to determine if LRP5 is a PCSK9 target, study the association between PCSK9 and Wnt/β-catenin signaling, and elucidate its effect on myocardial infarction in patients with ischemic cardiomyopathy.

Methods

The expression of Lrp5, phospho-β-catenin, total β-catenin was evaluated by western blot analysis, and the effects of overexpressed PCSK9 were tested under normoxia, hypoxia, or hypoxia/re-oxygenation (H/R) in mouse cardiomyocytes (HL-1). The transcriptional activity of β-catenin was assessed using the TOP-Flash/FOP-Flash luciferase reporter assay. In addition, the impact on various downstream targets of the Wnt/β-catenin signaling pathway was assessed using a quantitative real-time polymerase chain reaction. To examine whether PCSK9 regulates injury of cardiomyocytes in vivo, we subjected transgenic mice with cardiac-specific overexpression of PCSK9 (PCSK9 TG) and wild-type (WT) mice to either sham surgery or ischemia/reperfusion (I/R) surgery.

Results

Under hypoxic conditions, the Wnt/β-catenin signaling pathway-related genes were downregulated in HL-1 cells, as evidenced by lower Lrp5 and active phospho-β-catenin expression levels (0.5-fold, n=3, p&lt;0.01). After H/R, the Wnt/β-catenin-related genes were recovered (1.5-fold, p&lt;0.01) in the control group but not in the PCSK9 overexpressed group. In the luciferase reporter assay results, PCSK9 overexpression inhibited the recovery of β-catenin transcriptional activity after H/R, in contrast to the control group. Furthermore, mRNA levels of Axin2, Cyclin D1, which are the Wnt/β-catenin signaling downstream pathway targets, were down-regulated under hypoxia and recovered after H/R but did not recover in PCSK9 overexpressed cells. In the mouse I/R model, the overall protein levels of the Wnt/β-catenin signaling-related genes were down-regulated in PCSK9 TG mice compared to WT mice after I/R injury.

Conclusions

These results indicated that the regulation of PCSK9 is closely associated with the Wnt/β-catenin signaling pathway which may play a crucial role in damaged cardiomyocytes. It suggests that the regulation of PCSK9 could be a therapeutic target in patients with ischemic cardiomyopathy.

Funding Acknowledgement

Type of funding sources: None.

Degradation of iopromide during the UV-LED/chlorine reaction: Effect of wavelength, radical contribution, transformation products, and toxicity

Three different UV-LED wavelengths (265, 310, and 365 nm) were used in the UV-LED/chlorine reaction to investigate the degradation mechanism of iopromide (IPM) at different wavelengths, a representative iodinated contrast media compound. The degradation rate (k'_IPM) increased from pH 6-8 at 265 nm, but, decreased as the pH increased up to 9 at 310 nm and 365 nm. Radical scavenging experiments showed that reactive chlorine species (RCS) are the dominant radical species at all wavelengths, but a higher contribution of OH• was observed at lower pH and longer wavelengths. The contribution of RCS decreased but the contribution of OH• increased as the wavelength increased. Among RCS, the largest contribution was found to be ClO•. Total nine transformation products (TPs) were identified by LC-QTOF-MS during the UV-LED/chlorine reaction at 265 nm. Based on the identified TPs and their time profiles, we proposed a degradation pathway of IPM during UV-LED/chlorine reaction. The Microtox test using V. fischeri showed that no significant increase in toxicity was observed at all wavelengths. The synergistic effect of UV-LED and chlorine was greater at a higher wavelength by the electrical efficiency per order (EEO) calculation.

Atypical periprosthetic femoral fracture with stem breakage: a case report

Although the American Society for Bone and Mineral Research definition of atypical femoral fracture excludes periprosthetic fractures, fractures around the prosthesis with clinical features of atypical femoral fractures have been reported in the literature. All fractures reported thus far have been distal to the prosthetic segment; however, we encountered a case of a stress fracture in the middle of the femoral component segment. An 86-year-old woman with a history of bisphosphonate osteoporosis treatment and revisional total hip arthroplasty visited our outpatient clinic complaining of pain in the left thigh and groin. We diagnosed an incomplete atypical femoral fracture around the hip prosthesis; medical treatment was implemented. Two months later, the patient visited the emergency department with a complete subtrochanteric fracture with stem breakage. Without revision of the broken stem, two plates were applied after reduction. In this case, we recognized the possibility of a stress fracture but overlooked the possibility of stem breakage in an atypical femoral fracture. Even if it is not evident on the radiograph before complete fracture, clinicians should be alert to the signs of stress fracture in the middle of the femoral component segment, as they may be clues to atypical periprosthetic femoral fracture with stem failure. Isolated medical treatment plans are not recommended for incomplete subtrochanteric atypical periprosthetic femoral fracture. Instead, concomitant prophylactic plate fixation is recommended.

Propiconazole degradation and its toxicity removal during UV/H2O2 and UV photolysis processes

Propiconazole (PRO) is a triazole fungicide that is frequently detected in the water. In this study, we investigated the kinetics and degradation mechanism of PRO during the UV photolysis and UV/H₂O₂ processes. PRO was removed by the pseudo-first-order kinetics in both processes. The removal of PRO was enhanced by increasing H₂O₂ concentration in the UV/H₂O₂ process. The highest removal under neutral conditions, and lower removal of PRO were observed in acidic and alkaline pHs in the UV/H₂O₂ process. The presence of natural water ingredients such as Cl^-, NO₃^-, humic acid acted as radical scavengers, but HCO₃^- ion acted as both radical promoter and scavenger in the UV/H₂O₂ process. The transformation products (TPs) of PRO during both processes were identified using LC-QTOF/MS. Four TPs ([M+H]⁺ = 238, 256, 306, and 324) were identified during UV photolysis, and six TPs ([M+H]⁺ = 238, 256, 306, 324, 356, and 358) were identified in the UV/H₂O₂ process. Among the identified TPs, TP with [M+H]⁺ values of 356 and 358 were newly identified in the UV/H₂O₂ process. In addition, ionic byproducts, such as Cl^-, NO₃^-, formate (HCOO^-), and acetate (CH₃COO^-), were newly identified, indicating that significant mineralization was achieved in the UV/H₂O₂ process. Based on the identified TPs and ionic byproducts, the degradation mechanisms of PRO during two processes were proposed. The major reactions in both processes were ring cleavage and cyclization, and hydroxylation by OH radicals. The Microtox test with Vibrio fischeri showed that, while the toxicity of the reaction solution increased first, then gradually decreased during UV photolysis, the UV/H₂O₂ process initially increased toxicity at 10 min due to the production of TPs, but toxicity was completely removed as the reaction progressed. The results obtained in this study imply that the UV/H₂O₂ process is an effective treatment for eliminating PRO, its TPs, and the resulting toxicity in water.

Activation pattern during his pacing: how close are we to normal physiology?

Background

His bundle pacing aims to mimic the activation pattern of normal conduction to maintain ventricular synchrony. However, selective His capture can be challenging, and the activation sequence during His pacing may not replicate normal conduction.

Purpose

Compare the right ventricular (RV) and left ventricular (LV) activation pattern in sinus rhythm and His bundle pacing.

Methods

Baseline LV and RV map was created in sinus rhythm using Rhythmia mapping system (Boston Scientific Corporation) in canine animal model. Medtronic 3830 lead was placed near the bundle of His under fluoroscopic, intracardiac echocardiogram, and electroanatomic guidance. Conduction system capture was confirmed by observing a QRS duration &lt;120ms and an isoelectric segment between pacing artifact and QRS on surface ECG. Repeat LV and RV activation map was obtained during His pacing. Average QRS, HV and pacing to V intervals were calculated with standard deviation.

Results

Mapping was performed successfully in four animals. At baseline, the average QRS duration was 44±2.6ms and HV interval was 32±4.2ms. Earliest site of myocardial activation was in the mid-septal LV region. The earliest RV myocardial activation was also at the septum closer to the apex, but later than the LV (Figure1A). With His pacing, the average QRS duration was 70±17.0ms and the average stim to V interval was 31±8.7ms. During His pacing, the earliest site of activation was in the RV septum, with an activation pattern from base to apex in both the RV and LV.

Conclusion

Unlike normal physiology, the activation pattern during conduction system pacing is from base to apex with earliest site in the RV.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Mayo Clinic

Energy-efficient erythromycin degradation using UV-LED (275 nm)/chlorine process: Radical contribution, transformation products, and toxicity evaluation

In this study, we investigated the degradation mechanism of erythromycin (ERY) during UV-LED/chlorine treatment using a 275-nm ultraviolet light-emitting diode (UV-LED). This wavelength is known to generate fewer disinfection byproducts (DBPs), and to have higher energy and photon yield efficiency compared to low pressure mercury (LP-UV) lamp which emits 254 nm of UV radiation. The degradation of ERY during the UV-LED/chlorine reaction followed pseudo-first-order kinetics. While Cl• and ClO• radicals along with other secondary radicals played key roles in the degradation of ERY at alkaline pH conditions, •OH radical was the main contributor at acidic pH conditions. Using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS), we tentatively identified six byproducts. Trace amounts of DBPs, such as chloroform (CHCl₃) and chlorate (ClO₃^-) ions, were also detected at less than 0.3 mg/L. There was no residual antibiotic effect at the end of the UV-LED/chlorine reaction due to the complete degradation of important moieties, such as macrolide, in ERY. Toxicity decreased by 20% after 20 min during the UV-LED/chlorine process of ERY (1.0 mg/L) degradation. Finally, we confirmed the inactivation of ARB and ARG during the UV-LED/chlorine process.

P2851Transvenous lead placement in the setting of venous obstruction: outcomes of tunneling technique versus venoplasty

Background

Venous stenosis is a well-recognized complication of transvenous leads when patients require lead revisions or device upgrade. In these cases, balloon venoplasty or alternative venous access with subcutaneous tunneling can be performed.

Purpose

Compare the outcomes of venoplasty vs. tunneling in patients requiring additional transvenous lead implantation.

Methods

A single center retrospective cohort study of all patients undergoing lead implantation/revision requiring venoplasty or tunneling from 2005–2017. Chi-squared and Wilcoxon Rank-Sum tests were used to compare categorical and continuous variables.

Results

Ninety five patients met our inclusion criteria (60 venoplasty & 35 tunneling). There was no difference in procedure success rates (p-value=0.98). Tunneling was associated with less fluoroscopy time but higher incidence of acute complications (0% vs. 23%, p-value=0.002) most requiring invasive intervention and/or blood product transfusion. Long term outcomes were comparable and related to lead failure or infection.

Outcomes for tunneling vs. venoplasty Variable Tunneling (n=35) Venoplasty (n=60) p-value Age Y 67 (23–84) 70 (29–91) 0.25 Male (%) 24 (69%) 41 (68%) 0.98 Number of existing leads 2.1 (1–4) 2.4 (0–4) 0.1 Age of oldest lead 7.0 (0–21) 7.2 (0–33) 0.73 Number of new leads 1.2 (1–3) 1.4 (1–3) 0.26 Fluoroscopy time (SD) min 29.2 (21.3) 39.7 (21.5) 0.012 Procedure success (%) 35 (100%) 55 (92%) 0.9 Acute complications (%) 8 (23%)1 0 (0%) 0.0002   Pocket hematoma/bleed 4 (11%)2   Hemothorax 2 (6%)3   Pericarditis 1 (3%)   Lead compromise 1 (3%) Follow up M 18 (0–76) 28 (0–98) N/A Long term lead issues (%) 6 (17%) 10 (17%) 0.95 Long term complication requiring intervention 4 (11%) 8 (13%) N/A Procedure success: functional lead placed as a result of venoplasty or tunneling. 1Two patients required blood products. 2Two patients required invasive intervention. 3One patient required chest tube and the other ICU admission.

Conclusions

Balloon venoplasty is associated with similar rates of success and a less incidence of acute complications when compared subcutaneous tunneling.

Acknowledgement/Funding

NIH T32 Training Grant HL07111-40

Size-separated particle fractions of stainless steel welding fume particles - A multi-analytical characterization focusing on surface oxide speciation and release of hexavalent chromium

Welding fume of stainless steels is potentially health hazardous. The aim of this study was to investigate the manganese (Mn) and chromium (Cr) speciation of welding fume particles and their extent of metal release relevant for an inhalation scenario, as a function of particle size, welding method (manual metal arc welding, metal arc welding using an active shielding gas), different electrodes (solid wires and flux-cored wires) and shielding gases, and base alloy (austenitic AISI 304L and duplex stainless steel LDX2101). Metal release investigations were performed in phosphate buffered saline (PBS), pH 7.3, 37°, 24h. The particles were characterized by means of microscopic, spectroscopic, and electroanalytical methods. Cr was predominantly released from particles of the welding fume when exposed in PBS [3-96% of the total amount of Cr, of which up to 70% as Cr(VI)], followed by Mn, nickel, and iron. Duplex stainless steel welded with a flux-cored wire generated a welding fume that released most Cr(VI). Nano-sized particles released a significantly higher amount of nickel compared with micron-sized particle fractions. The welding fume did not contain any solitary known chromate compounds, but multi-elemental highly oxidized oxide(s) (iron, Cr, and Mn, possibly bismuth and silicon).

Drug repurposing from the perspective of pharmaceutical companies

Drug repurposing holds the potential to bring medications with known safety profiles to new patient populations. Numerous examples exist for the identification of new indications for existing molecules, most stemming from serendipitous findings or focused recent efforts specifically limited to the mode of action of a specific drug. In recent years, the need for new approaches to drug research and development, combined with the advent of big data repositories and associated analytical methods, has generated interest in developing systematic approaches to drug repurposing. A variety of innovative computational methods to enable systematic repurposing screens, experimental as well as through in silico approaches, have emerged. An efficient drug repurposing pipeline requires the combination of access to molecular data, appropriate analytical expertise to enable robust insights, expertise and experimental set-up for validation and clinical development know-how. In this review, we describe some of the main approaches to systematic repurposing and discuss the various players in this field and the need for strategic collaborations to increase the likelihood of success in bringing existing molecules to new indications, as well as the current advantages, considerations and challenges in repurposing as a drug development strategy pursued by pharmaceutical companies.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

Adiponectin Levels in Non-obese First-degree Relatives of Type 2 Diabetes Patients and Non-diabetic Subjects: A 5-Year Follow-up Study

This study was designed to investigate adiponectin levels and their relationship to various parameters at baseline and after 5 years in non-obese first-degree relatives of type 2 diabetes patients (FDR group) versus subjects without a family history of diabetes (normal group). Adiponectin levels at baseline were lower in the FDR group versus the normal group. After 5 years, adiponectin levels had fallen significantly in both the FDR (24.3% reduction) and the normal (35.7% reduction) groups. Adiponectin levels were negatively correlated with waist/hip ratio, fasting plasma glucose, carotid intima-media thickness (IMT) and insulin resistance in the FDR group. When adjusted for relevant risk factors, adiponectin was associated with age, high-density lipoprotein-cholesterol and IMT; these factors explained 45% of the variation in adiponectin in the FDR group. In the normal group, multiple regression analyses revealed that low-density lipoprotein-cholesterol and IMT explained 25% of the variability in the adiponectin concentration. In both groups, however, the correlation between adiponectin and IMT just failed to reach statistical significance in this population group. We conclude that adiponectin levels were reduced in non-obese first-degree relatives of patients with type 2 diabetes and normal individuals over a 5-year period. This study supports previous findings that hypoadiponectinaemia is a risk factor for atherosclerosis.

The incidence, risk factors and prognostic implications of venous thromboembolism in patients with gastric cancer

BACKGROUND

Data on venous thromboembolism (VTE) in gastric cancer (GC) are very scarce.

OBJECTIVE

To investigate the incidence, risk factors and prognostic implications of VTE in Asian GC patients.

METHODS

Prospective databases containing clinical information on GC patients (n = 2,085) were used.

RESULTS

The 2-year cumulative incidences of all VTE events were 0.5%, 3.5% and 24.4% in stages I, II-IV(M0) and IV(M1), respectively. Advanced stage, older age and no major surgery were independent risk factors for developing VTE. When the VTE cases were classified into extremity venous thrombosis (EVT), pulmonary thromboembolism (PTE) or intra-abdominal venous thrombosis (IVT), IVTs (62%) were more common than EVTs (21%) or PTEs (17%). Although peri-operative pharmacologic thromboprophylaxis was not routinely administered, the VTE incidence after major surgery was only 0.2%. During chemotherapy, EVT/PTE developed more frequently than IVT (54% vs. 19%); however, during untreated or treatment-refractory periods, IVT developed more frequently than EVT/PTE (69% vs. 36%). In multivariate models, the development of EVT/PTE was a significant predictor of early death when compared with no occurrence of VTE (P < 0.05). However, IVT did not affect survival.

CONCLUSION

This is the largest study that specially focused on VTE in GC and the VTE incidence in Asian GC patients was first demonstrated. Considering the low incidence of post-operative VTE development, the necessity of peri-operative pharmacologic thromboprophylaxis should be evaluated separately in Asian patients. The clinical situation of the development of EVT/PTE and IVT differed. Only EVT/PTE had an adverse effect on survival and IVT had no prognostic significance.

Prospective evaluation of oral mucositis in solid tumor patients undergoing chemotherapy and its clinical implication

e20650

Background: Oral mucositis (OM) induced by chemotherapy is a troublesome and debilitating adverse effect in solid tumor patients. OM might influence the complicated aspects such as the poor oral intake and malnutrition over just oral symptom. Therefore we prospectively evaluated the actual incidence of OM and its clinical significance in solid tumor patients. Methods: From October 16, 2007 to September 3, 2008, we consecutively enrolled 344 patients with solid tumor who initiated new chemotherapy. Each patient was prospectively evaluated for two cycles. The data were collected from physician-to-patient interview. And patients’ diary for OM symptom was used as patient-reported measurement. The visual analog scale (VAS) was used to quantify the degree of adverse effects (VAS: 0 point = no symptoms, 4 point = the worst symptom) and FACT-G was used for assessment of the quality of life (QOL). Results: Finally, 322 patients were analyzed. The median age was 51. Breast cancer was the most common (51%). And, stage IV was 137 (43%). OM was 28% per each cycle and 45% per patient during two cycles. Patient-reported OM symptom had peak in one week and was recovered in 9.14±6.77 days. Oral dryness was the most prevalent symptom out of symptoms related with OM such as oral pain, poor oral intake, dysphagia, oral bleeding, scalloping of tongue and ulceration (VAS score 1≤; 47%, 27%, 39%, 15%, 7%, 14%, 13%, respectively). In QOL measured by FACT-G, physical well-being and emotional well-being were significantly dropped in OM-occurred group than in no-OM group (19.09±6.48 vs 22.47±5.95, p<0.001; 16.74±4.10 vs 17.97±3.38, P<0.001, respectively). In addition, higher VAS score for other adverse effects was showed in OM-occurred group than in no-OM group (activity, nausea, vomiting, fever, myalgia and nervous system; p=0.0038, p<0.0001, p=0.0007, p=0.0062, p<0.0001, p<0.0001, respectively). Conclusions: Forty five percent of patients with solid tumor experience OM during 2 cycles of chemotherapy. In case of patients with OM, QOL is worse and the other adverse effects are more prevalent. OM could be an indicator of QOL and other adverse effects during chemotherapy.

No significant financial relationships to disclose.

Temporal and spatial characterization of harmonics structures of relativistic nonlinear Thomson scattering

The harmonics of the scattering of a femtosecond intense laser pulse by an electron has been numerically investigated. The harmonic spectrum shows interesting red shifts and parasitic lines in the blue sides of harmonic lines. The red shift of the lines is found to be caused by the dilation of laser oscillation experienced by an electron due to its relativistic drift motion along the direction of a driving laser propagation and the parasitic lines come from the variation of the laser intensity. The angular distribution of each higher harmonic line shows double peak patterns in the forward direction. The backward scattering has its own distinct pattern: line-shaped nodes perpendicular to the laser electric field, the number of which is the harmonic order number minus one. As the harmonic order increases, the primary peaks of higher harmonics move from the backward to the forward direction of the laser propagation. In the time domain, each radiation pulse in the case of a linearly-polarized laser pulse has a double peak structure due to the disappearance of the acceleration during the half cycle of an electron's oscillation.

[A primary study on distribution and binding forms of arsenic in polluted crop seeds]

The distribution, binding form and processing removal of arsenic in rice and wheat seeds were studied. The result shows that the distribution of arsenic in seed parts was uneven, as concentration in rice seed was embryo > seed capsule > chaff > endosperm, and that in wheat seed was embryo > seed capsule > endosperm. Arsenic was mainly accumulated in endosperm, and mainly in the form of protein-binding. With the removal of chaff, coarse rice bran and fine rice bran in the processing, the content of arsenic decreased by 16.51%, 12.41% and 10.26%, respectively. Similarly, with the removal of coarse wheat bran and fine wheat bran, it decreased by 22.0% and 45.6%, respectively.

[Cancer mortality in high background radiation area of Yangjiang, China, 1979-1995]

OBJECTIVE

To estimate cancer risk associated with the low level radiation exposure of average annual effective dose of 6.4 mSv in HBRA the high background radiation area (HBRA) of Yangjiang, China.

METHODS

The cancer mortality data of 1979-1986 were collected from a dynamic cohort by prospective survey. The data of 1987-1995 were obtained from a fixed cohort by retrospective and/or prospective survey. The mortality investigation on the spot consisted of two steps, i.e. the follow-up of the members in the cohort and the ascertainment of the death causes. The estimate of cumulative individual dose of the cohort members included that of the exposure from natural external and internal sources. Both direct (TLD measurement) and indirect (environmental measurement and occupancy pattern) approaches were used for individual external dose estimate. On the basis of the hamlet-specific average annual external dose, the cohort members were classified into four groups for internal comparison: high, medial and low dose groups from HBRA and control group from control area (CA). Relative risk (RR) and excess relative risk coefficient (ERR per sievert) and its 95% confidence interval (CI) was estimated using AMFIT program in Epicure.

RESULTS

During the period 1979-1995, there were 10,415 total deaths and 1003 cancer deaths among 1,698,350 person-years at risk in the cohort of 125,079 subjects. The adjusted RR (95% CI) with sex and age group for all cancers of whole HBRA was 0.99 (0.87-1.14). As for the site-specific cancer of whole HBRA, the RRs of cancers of stomach, colon, liver, lungs, bone, female breast, and thyroid were less than one, while the RRs of cancers of nasopharynx, esophagus, rectum, pancreas, skin, cervix uterus, brain and central nervous system, leukemia and lymphoma were larger than one. However, all of them except for esophagus cancer were not different statistically from one (P > 0.05). The homogeneity tests of RRs for all cancers and for site-specific cancer among the three dose groups in HBRA revealed that the RRs in these dose groups were not different statistically (P > 0.05) for all. The ERR (95% CI)/Sv of all cancers for both sexes and all ages was -0.10 (-0.67, 0.69).

CONCLUSION

An increased cancer risk associated with the high levels of natural radiation in HBRA was not found. On the contrary, the mortality of all cancers in HBRA was generally lower than that in CA, but not significant statistically.

Existence and uniqueness of endemic states for the age-structured S-I-R epidemic model

The existence and uniqueness of positive steady states for the age structured S-I-R epidemic model with intercohort transmission is considered. Threshold results for the existence of endemic states are established for most cases. Uniqueness is shown in each case. Threshold used are explicitly computable in terms of demographic and epidemiological parameters of the model.

Electrophysiologic Effects of the New Class III Antiarrhythmic Drug Dofetilide in an Experimental Canine Model of Pacing-induced Atrial Fibrillation

BACKGROUND: Dofetilide is a new class III antiarrhythmic drug currently under investigation for the treatment of supraventricular arrhythmias in humans. Dofetilide have been previously shown to be highly effective in terminating and suppressing reentrant atrial flutter in the experimental canine crush-injury model, in which its antiarrhythmic efficacy was correlated with prolongation of wavelength and reduction in dispersion of refractoriness, effects not produced by the class IA antiarrhythmic drug quinidine. The purpose of this study was to evaluate the antiarrhythmic efficacy and mechanisms of action of dofetilide in an experimental model of atrial fibrillation. METHODS AND RESULTS: Dofetilide was administered intravenously to seven open-chest dogs with acute sustained atrial fibrillation induced by rapid atrial pacing for up to 4 hours. Mean atrial effective refractory period (ERP), dispersion of ERP, conduction velocity and wave-length were determined by multipoint right atrial programmed stimulation and activation mappin gusing a 56-electrode mapping plaque on the right atrial free wall. Dofetilide prolonged average ERP by 22% from 104 +/- 13 to 127 +/- 15 ms (P <.001), prolonged maximum ERP by 11% from 129 +/- 7 to 143 +/- 10 (P <.003), had no effect on conduction velocity at 200 ms pacing cycle length, slowed conduction velocity by 16% from 0.89 +/- 12 to 0.75 +/-.17 ms at 150 ms pacing cycle length, slowed conduction velocity by 16% from 0.89 +/- 12 to 0.75 +/-.17 ms at 150 ms pacing cycle length (P <.001), increased wavelength by 20% from 93 +/- 7 to 112 +/- 9 mm (P <.01), reduced dispersion of ERP by 24% from 11.4 +/- 2.9 to 8.7 +/- 2.3 (P =.016), and reduced the number of adjacent electrodes with ERP difference >/=20 ms by 67% from 18.4 +/- 7.1 to 6.1 +/- 4.2 (P <.001). Dofetilide reduced the number of excitation wavelets (total over three beats) entering the region of the mapping plaque by 38% from 5.0 +/-.8 to 3.1 +/-.4 (P <.002). Dofetilide terminated atrial fibrillation in all seven dogs at a mean of 3.4 +/- 2.2 minutes into the loading infusion and prevented reinduction of atrial fibrillation in all seven dogs after completion of the loading infusion, while on maintenance infusion. Time to termination of atrial fibrillation correlated closely with change in ERP (r = 0.78, P =.036). CONCLUSIONS: Dofetilide was highly effective in terminating and suppressing sustained pacing induced atrial fibrillation in this canine model. Time to termination of atrial fibrillation correlated with the degree of change in ERP produced by dofetilide. The mechanism of termination of atrial fibrillation by dofetilide appeared to be a progressive reduction and eventual extinction of re-entrant wavelets. The predominant electrophysiologic effects of dofetilide were prolongation of ERP and wavelength and a reduction in dispersion of refractoriness. Dofetilide had little effect on conduction velocity in this model, except at very short pacing cycle lengths.

Stabilization of granulocyte colony-stimulating factor and structurally analogous growth factors by anionic phospholipids

Recombinant granulocyte colony-stimulating factor (rhG-CSF) interacts with liposomes composed of the anionic phospholipid dioleoylphosphatidylglycerol (DOPG), and this interaction enhances the stability of the protein [Collins, D., & Cha, Y. (1994) Biochemistry 33, 4521-4526]. In the present studies, we have examined the interaction of rhG-CSF with phospholipids other than DOPG. Fluorescence spectroscopy of rhG-CSF with a variety of lipid vesicles demonstrated that rhG-CSF inserts into bilayers of anionic, but not zwitterionic, phospholipids. Isothermal titration calorimetry of the interaction between DMPG and rhG-CSF indicates that the binding is saturable and involves 10 lipids/rhG-CSF. Studies of phosphatidylglycerols with varying alkyl chain lengths determined that the stabilization of rhG-CSF by anionic phospholipids required a certain alkyl chain length; no stabilization was observed with lipids of shorter chain length. Also investigated was the stabilization of other growth factors, which are structurally similar to rhG-CSF, by anionic phospholipids. These proteins include recombinant porcine somatotropin (rpSt), recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF), recombinant human interleukin 4 (rhIL-4), and recombinant human interleukin 2 (rhIL-2). The helical secondary structure of the proteins was recoverable after heating and cooling in the presence of anionic phospholipids as observed by circular dichroism; the presence of zwitterionic lipids did not induce this effect. Results of these investigations concluded that a group of structurally similar proteins interact preferentially with anionic phospholipids and that the complexation of the growth factors with vesicles composed of anionic phospholipids improves the stability of the proteins under conditions where they normally denature.

Electrophysiologic effects of the new class III antiarrhythmic drug dofetilide compared to the class IA antiarrhythmic drug quinidine in experimental canine atrial flutter: role of dispersion of refractoriness in antiarrhythmic efficacy

INTRODUCTION

Previous studies suggest that class III antiarrhythmic drugs are more effective in reentrant arrhythmias because they prolong refractoriness (ERP) and wavelength and reduce dispersion of refractoriness compared to Class IA antiarrhythmic drugs, which slow conduction velocity (CV) in addition to their effects on refractoriness.

METHODS AND RESULTS

To test this hypothesis, the Class III drug dofetilide and the Class IA drug quinidine were studied in the experimental canine crush-injury model of atrial flutter, utilizing right atrial multipoint programmed stimulation and activation mapping. In seven dogs dofetilide prolonged ERP by 23%, slowed CV by 9% at 200-msec cycle length (P < 0.001) and by 39% at 150-msec cycle length (P < 0.001), and increased wavelength by 11% (P < 0.02). Dofetilide reduced dispersion of ERP by 20% (P = 0.003) and adjacent electrodes with ERP difference > or = 20 msec by 76% (P < 0.001). Dofetilide slowed atrial flutter by 37% (P = 0.003) prior to terminating and suppressing it in all dogs. In eight dogs quinidine prolonged ERP by 14% (P < 0.001), slowed CV by 14% at 200-msec length cycle (P < 0.001) and by 19% at 150-msec cycle length (P < 0.001), and reduced wavelength by 2% (P = NS). Quinidine did not reduce dispersion of refractoriness. Quinidine slowed atrial flutter by 57% (P < 0.001), terminating and suppressing it in only three dogs. Efficacy of dofetilide was greater than quinidine (P = 0.026) and correlated with reduced dispersion of ERP (r = -0.653, P = 0.01), reduced adjacent electrodes with ERP difference > or = 20 msec (r = -0.637, P = 0.012), and prolonged wavelength (r = 0.61, P = 0.018). Dofetilide and quinidine terminated atrial flutter by similar mechanisms. Myocardial fiber orientation was nonuniform around the crush injury.

CONCLUSIONS

Antiarrhythmic efficacy of dofetilide was greater than that of quinidine and correlated with drug-induced prolongation of wavelength and reduction in dispersion of refractoriness, effects produced only by dofetilide.

p53-independent induction of WAF1/CIP1 in human leukemia cells is correlated with growth arrest accompanying monocyte/macrophage differentiation

The p53 tumor suppressor gene plays a role in controlling a G1 phase checkpoint. The WAF1/CIP1 gene with encodes p21WAF1/CIP1 protein, an inhibitor of cyclin-dependent kinases, is a downstream mediator of p53 function. We examined expression of the WAF1/CIP1 gene and its relationship to growth arrest and differentiation in p53-null human leukemic cell lines. We show that p53-independent induction of WAF1/CIP1 occurs in human leukemia cells treated with 12-O-tetradecanoylphorbol-13-acetate, okadaic acid, or IFN-gamma but not with retinoic acid, vitamin D3, or DMSO. Furthermore, WAF1/CIP1 induction correlates with growth arrest associated with monocyte-macrophage differentiation. The present studies support the idea that WAF1/CIP1 gene expression can be regulated through multiple mechanisms, suggesting that strategies may be designed to restore the G1 checkpoint controls in p53-null cells by targeting these p53-independent mechanisms of WAF1/CIP1 induction.

Interaction of recombinant granulocyte colony stimulating factor with lipid membranes: enhanced stability of a water-soluble protein after membrane insertion

The interaction of recombinant granulocyte colony stimulating factor (rhG-CSF) with lipid vesicles was studied. In the presence of dioleoylphosphatidylglycerol (DOPG) vesicles, the intrinsic fluorescence of rhG-CSF exhibits dramatic changes. In particular, tryptophan fluorescence is greatly enhanced and the emission maximum shifted to lower wavelengths. The presence of DOPG vesicles causes the protein tryptophans to become inaccessible to iodide, a water-soluble quencher of tryptophan fluorescence, yet accessible to quenching via energy transfer to pyrenyl decanoic acid, a lipid-soluble fluorescent probe. The data suggest that rhG-CSF inserts into lipid vesicles composed of DOPG. The driving force for the insertion may be a conformational change induced by the low pH at the lipid-water interface of DOPG vesicles. The DOPG-inserted form of rhG-CSF retains biological activity and shows remarkable stability, even under high-temperature conditions which lead to denaturation of rhG-CSF alone. Membrane insertion of G-CSF may be involved in the in vivo activity of this important cytokine.

Human interferon regulatory factor 2 gene. Intron-exon organization and functional analysis of 5'-flanking region

Interferon regulatory factor 2 (IRF-2) is a transcriptional regulatory protein that terminates interferon beta expression initiated by interferon regulatory factor 1. In this study, we isolated the genomic DNA for human IRF-2 gene, determined the intron-exon structure of the human IRF-2 gene, mapped the major transcription initiation site, identified a number of potential regulatory elements in the 5'-flanking region, and localized the IRF-2 gene on human chromosome 4. The IRF-2 promoter region contains a CpG island, with several GC boxes, a putative NF-kappa B-binding site, and a CAAT box, but no TATA box. When the promoter region was linked with a heterologous reporter gene, we found that the promoter region is inducible by both interferons (interferon-alpha and -gamma) and interferon regulatory factor 1. The region which induced these inductions was identified as being confined to 40 nucleotides 5' to the major transcriptional initiation site by testing a series of clones with truncated promoter of IRF-2. This region contains elements which are shared with the transcriptional enhancers of other genes including interferon regulatory factor 1, interferon beta, and interferon-inducible genes. These data suggest that interferon regulatory factor 1 not only triggers the activation of the interferon signal transduction pathway, but also may play a role in limiting the duration of this response by activating the transcription of IRF-2.

Molecular approaches to the diagnosis and treatment of cancer

We have used autologous bone marrow transplantation (ABMT) as a setting to develop the genetic therapy of cancer in hematopoietic neoplasms based on the use of the bone marrow as a conduit through which to introduce regulatory molecules into the patient. This has involved three developmental phases: 1) learning how to develop genetic modification techniques; 2) learning how to develop in vivo selection techniques for the genetically modified cells; and 3) developing molecular vectors for modification of hematopoietic cells for therapy of cancer. These programs will be summarized in terms of their progress at the conference.

The motif Tyr-X-X-hydrophobic residue mediates lysosomal membrane targeting of lysosome-associated membrane protein 1

We have investigated the mechanism by which LAMP-1, a principal protein of the lysosomal membrane, is targeted to lysosomes. Mutagenesis and transfection experiments indicate that the motif Tyr-X-X-hydrophobic residue at the carboxyl terminus of the 11-amino acid cytoplasmic tail of the protein constitutes the lysosomal targeting signal for LAMP-1. This motif directs CD44, a cell surface hyaluronate receptor, to the lysosomal membrane, but only when the signal is placed at the carboxyl-terminus of a truncated cytoplasmic tail. The signal did not confer lysosomal targeting when it was situated internally or at the carboxyl terminus of the normal CD44 cytoplasmic tail. An apparent paradox is that similar Tyr-containing sequences mediate internalization, but not lysosomal targeting, of several receptors. Of possible relevance is the additional finding that purified LAMP-1 protein lacks the two carboxyl-terminal residues predicted by cDNA, both of which are essential for proper trafficking. A model is proposed in which lysosomal targeting is distinguished from receptor internalization through proteolytic modification of the internalization signal.

A novel interferon-inducible domain: structural and functional analysis of the human interferon regulatory factor 1 gene promoter

We have cloned and functionally characterized the human interferon regulatory factor 1 (IRF-1) gene promoter. The promoter contains a CpG island, with several GC boxes, a CAAT box, but no TATA box. IRF-1 mRNA is strongly induced by gamma interferon (IFN-gamma) but more weakly and transiently by IFN-alpha. There are several putative kappa B motifs and numerous AA(G/A)G(G/T)A and GAAANN motifs throughout the promoter. The IRF-1 promoter is not autoregulated by the IRF-1 gene product. IFN inducibility of the promoter was studied with 5' deletion mutants linked to a heterologous reporter gene. Gel mobility shift assays were used to show IFN-inducible factor binding to the IRF-1 promoter. These studies showed that IFN inducibility is conferred by a novel imperfect inverted-repeat arrangement of two GAAANN motifs within a domain, 130 nucleotides upstream of transcription initiation. This inverted repeat binds a factor upon induction with IFN and can confer IFN inducibility on a heterologous promoter. Conversely, point mutations of the inverted repeat are not IFN inducible when linked to the same heterologous promoter.

Energy storage of linear and cyclic electron flows in photosynthesis

The energy storage of photosynthesis in the green alga Chlorella vulgaris was determined by pulsed, time-resolved photoacoustics. The energy storage of the linear electron transfer process in photosynthesis, of cyclic photosystem (PS) I, and possibly of PSII was determined by selection of excitation wavelength and of flash interval. At 695 nm excitation, a rather large cyclic PSI energy storage of 0.68 +/- 0.04 eV/quantum of energy at 8 ms after a 1-mus flash was obtained. This energy remained the same at flash intervals of 0.35 to 60 s and was independent of the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. We tentatively assign this energy to the ferredoxin-NADP-reductase-ferredoxin and oxidized cytochrome b(6)/f complexes. An efficient distribution of energy between cyclic and linear systems is obtained with the simple assumption that the turnover time of the cyclic system is slower than that of the linear system. The energy storage of linear electron flow was determined by 655 nm excitation of Chlorella with a short flash interval of 0.35 s per flash. It was calculated to be 0.50 +/- 0.03 eV/hv, close to that expected for oxygen and NADPH formation. The energy storage of PSII is determined by excitation of Chlorella at 655 nm with a long flash interval of 60 s per flash. It was calculated to be 1.07 +/- 0.05 eV/hv, consistent with the energy storage being in S-states and the secondary electron acceptor of PSII with a calculated redox energy of 1.03 eV/hv. In the presence of 1 mum 3-(3,4-dichlorophenyl)-1,1-dimethylurea, the calculated energy storage in PSII is still significant, 0.53 +/- 0.04 eV/hv. This probably indicates a significant cyclic electron flow around PSII. These cyclic flows may contribute considerably to energy storage in photosynthesis.

Role of internal thermodynamics in determining hydrogen tunneling in enzyme-catalyzed hydrogen transfer reactions

Previous investigations have indicated a role for hydrogen tunneling in the yeast alcohol dehydrogenase catalyzed oxidation of benzyl alcohol [Cha, Y., Murray, C. J., & Klinman, J. P. (1989) Science 243, 1325] and the bovine plasma amine oxidase catalyzed oxidation of benzylamine [Grant, K.L., & Klinman, J. P. (1989) Biochemistry 28,6597]. In the present studies, values of protium to tritium and deuterium to tritium isotope effects and their temperature dependencies have been measured using ring-substituted substrates for yeast alcohol dehydrogenase and bovine plasma amine oxidase, revealing tunneling in each case. The results of these studies indicate that hydrogen tunneling is a general phenomenon and is not limited to enzyme reactions with degenerate energy levels for bound substrates and products. An analysis of internal thermodynamics in the yeast alcohol dehydrogenase reaction shows that tunneling occurs when delta H degrees is endothermic and that the degree of tunneling appears to increase as delta H degrees decreases toward zero.

Human interferon regulatory factor 1: intron-exon organization

Interferon (IFN) regulatory factor 1 (IRF-1) is a transcriptional regulatory protein that mediates the transcriptional activation of the IFN-alpha and IFN-beta genes by viruses and IFNs. To characterize the mechanisms that govern the level of IRF-1 in cells, we isolated the IRF-1 gene and characterized the structure of its intronic and exonic domains and of its regulatory promoter region. A human placental genomic library was screened with an IRF-1 cDNA probe, and two clones that contained the IRF-1 gene and its 5' regulatory region were obtained. We used these clones to determine the complete nucleotide sequence for the IRF-1 gene, finding that the IRF-1 gene spanned 7.72 kb of DNA and included 10 exons and 9 introns. When the deduced amino acid sequences were compared among different species, the most conserved exons were exons 2, 3, and 4, in which the putative DNA binding domain for the IRF-1 protein is located.

The cDNA sequence of mouse LAMP-2. Evidence for two classes of lysosomal membrane glycoproteins

We describe the isolation and sequencing of a cDNA encoding the mouse lysosomal membrane glycoprotein mLAMP-2 and the sequence differences that distinguish this molecule from the LAMP-1 class of proteins. An oligonucleotide probe corresponding to the NH2-terminal amino acid sequence of purified mLAMP-2 was synthesized by the polymerase chain reaction and used to screen several cDNA libraries. cDNA clones with an insert of 1,700 nucleotides were identified and sequenced. The deduced amino acid sequence of mLAMP-2 comprises a signal sequence of 25 residues and a 390-amino acid polypeptide (Mr 43,017) with the following putative domains: a large intraluminal region (residues 1-354) with 17 N-linked glycosylation sites (Asn-X-Ser/Thr), a hydrophobic transmembrane-spanning region of 24 residues (355-378), and a COOH-terminal cytoplasmic tail of 12 residues (379-390). When this sequence is compared with those of other lysosomal membrane glycoproteins, it is apparent that mouse LAMP-2 and human LAMP-2 form one homology class (LAMP-2) that is separated from the LAMP-1 class of proteins. The sequence differences in these two classes provide a basis for comparing the structure of the proteins with their biochemical and biological properties.

The biodegradability of polyester blends

Blends of poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) with polyglycolic acid-co-L-lactic acid (PGLA) were prepared by three methods: compression moulding, coprecipitation, and solvent evaporation of a methylene chloride-in-water emulsion of the polymers. The rates of hydrolytic chain scission of each component of the blends were determined by deconvolution of GPC traces of samples maintained in phosphate buffer, pH 7.4, 37 degrees C, for up to 3000 h. The observed rates were dependent on the method of blending. For compression moulded blends, the rate of chain scission of PGLA was decreased and that of PCL and PLLA increased. A corresponding delay in the onset of weight loss was also observed. There was no evidence of blend miscibility.

Hydrogen tunneling in enzyme reactions

Primary and secondary protium-to-tritium (H/T) and deuterium-to-tritium (D/T) kinetic isotope effects for the catalytic oxidation of benzyl alcohol to benzaldehyde by yeast alcohol dehydrogenase (YADH) at 25 degrees Celsius have been determined. Previous studies showed that this reaction is nearly or fully rate limited by the hydrogen-transfer step. Semiclassical mass considerations that do not include tunneling effects would predict that kH/kT = (kD/kT)3.26, where kH, kD, and kT are the rate constants for the reaction of protium, deuterium, and tritium derivatives, respectively. Significant deviations from this relation have now been observed for both primary and especially secondary effects, such that experimental H/T ratios are much greater than those calculated from the above expression. These deviations also hold in the temperature range from 0 to 40 degrees Celsius. Such deviations were previously predicted to result from a reaction coordinate containing a significant contribution from hydrogen tunneling.