The carotenoids and membrane polypeptides of the light harvesting complex of mutants of Scenedesmus obliquus deficient in chlorophyll

The photosynthetic activities, the pigmentation and the chloroplast membrane polypeptides of several mutants of the green alga, Scenedesmus obliquus, with complete or limited deficiencies in the light-harvesting complex of photosystem II are characterized and compared to those of the normal phenotype.. The principal phenotype examined in this study, K0 -9, behaves similarly to the WT Scenedesmus in that it grows autotrophically, mixotrophically and heterotrophically; cells grown under these various conditions retain near normal photosynthetic capacity without alteration of either photosystem I or photosystem II activities. Also, the associated chloroplast membrane polypeptides, as well as the polypeptides of the apoproteins of the LHC-II, appear identical to those of the WT. However, absorption spectra analyses and gel electrophoresis studies revealed that the mutant lacks the major light-harvesting complex, LHCP-II ( as shown in "green" gels) and the corresponding chlorophyll a and chlorophyll h of the light-harvesting complex. Examination of total pigment extracts of WT and K0 -9 by HPLC revealed several obvious differences. The most apparent ones noted were the absence of chlorophyll 12 and the associated decreased level of chlorophyll A, a decreased level of neoxanthin and an increased concentration of violaxanthin in extracts of K0 -9. The level of these two xanthophylls appear to show an inverse relationship with neoxanthin decreasing by approximately 70% and violaxanthin increasing by a comparable amount. This noted relationship suggests that violaxanthin, a presumed precursor to neoxanthin, undergoes only limited conversion in IC0-9. Previous mutant studies on chlorophyll 12-deficient phenotypes of algae and higher plants also noted decreased levels of neoxanthin and in vitro reconstitution studies with the apoproteins of LHC-II showed that rebinding of chlorophyll h required various xanthophylls, specifically neoxanthin, also to be present. The other light-harvesting complex mutants of Scenedesmus examined in this study, including LF-1-LHC, LF-15 hf-17-LHC, CP-13- LHC, PS-28-LHC and LF-23-LHC, exhibit similar general deficiencies of chlorophyll h, lack the green bands of the LHCP-II but retain the apoproteins of this complex and show the same relationship between neoxanthin and violaxanthin as noted for K0 -9. Even though these strains were derived from mutant phenotypes already suffering major deletions in other parts of the photosynthetic apparatus, their inabilities to synthesize or to accumulate chlorophyll J show the same common factor as noted for K0 -9, i.e., the apparent accumulation of violaxanthin and decrease of neoxanthin. This suggests that the mutual site of mutation in these various phenotypes may reside at the point of conversion of violaxanthin to neoxanthin. This interpretation supports the concept that the precursor(s) to chlorophyll b must be initially bound near to or at the site within the chloroplast membrane where it will eventually function in the LHCP. Examination by detergent polyacrylamide gel electrophoresis (PAGE) of the light-harvesting complexes of isolated chloroplast fragments of the several phenotypes employed in this investigation confirmed that the inability to synthesize chlorophyll b was paralleled by the loss of the highly pigmented LHCP-II. However, in no case was it observed that the synthesis of the apoproteins of LHC-II, or their binding to the chloroplast membrane, was affected by the mutation causing chlorophyll b deficiency. Also no changes in electrophoretic mobility, i.e., apparent molecular weight, of either the 26 or 28 kDa polypeptides were noted in electrophoretic studies on control or heat denatured chloroplast fragments of the various phenotypes. Similarly PAGE of chromatographically purified samples of the LHC apoproteins of the WT and several mutants showed no alteration of electrophoretic mobility. These observations suggest, but do not prove, that the LHC-II apoproteins of the various phenotypes studied are not modified by the mutation causing loss of chlorophyll h synthesis

Variation in Intraoperative and Postoperative Utilization for 3 Common General Surgery Procedures.

ObjectiveThe aim of this study was to understand variation in intraoperative and postoperative utilization for common general surgery procedures.Summary background dataReducing surgical costs is paramount to the viability of hospitals.MethodsRetrospective analysis of electronic health record data for 7762 operations from 2 health systems. Adult patients undergoing laparoscopic cholecystectomy, appendectomy, and inguinal/femoral hernia repair between November 1, 2013 and November 30, 2017 were reviewed for 3 utilization measures: intraoperative disposable supply costs, procedure time, and postoperative length of stay (LOS). Crossed hierarchical regression models were fit to understand case-mixed adjusted variation in utilization across surgeons and locations and to rank surgeons.ResultsThe number of surgeons performing each type of operation ranged from 20 to 63. The variation explained by surgeons ranged from 8.9% to 38.2% for supply costs, from 15.1% to 54.6% for procedure time, and from 1.3% to 7.0% for postoperative LOS. The variation explained by location ranged from 12.1% to 26.3% for supply costs, from 0.2% to 2.5% for procedure time, and from 0.0% to 31.8% for postoperative LOS. There was a positive correlation (ρ = 0.49, P = 0.03) between surgeons' higher supply costs and longer procedure times for hernia repair, but there was no correlation between other utilization measures for hernia repair and no correlation between any of the utilization measures for laparoscopic appendectomy or cholecystectomy.ConclusionsSurgeons are significant drivers of variation in surgical supply costs and procedure time, but much less so for postoperative LOS. Intraoperative and postoperative utilization profiles can be generated for individual surgeons and may be an important tool for reducing surgical costs

Cost-Effectiveness of Surgically Induced Weight Loss for the Management of Type 2 Diabetes: Modeled Lifetime Analysis

OBJECTIVE--To estimate the cost-effectiveness of surgically induced weight loss relative to conventional therapy for the management of recently diagnosed type 2 diabetes in class VII obese patients. RESEARCH DESIGN AND METHODS--This study builds on a within-trial cost-efficacy analysis. The analysis compares the lifetime costs and quality-adjusted life-years (QALYs) between the two intervention groups. Intervention costs were extrapolated based on observed resource utilization during the trial. The proportion of patients in each intervention group with remission of diabetes at 2 years was the same as that observed in the trial. Health care costs for patients with type 2 diabetes and outcome variables required to derive estimates of QALYs were sourced from published literature. A health care system perspective was adopted. Costs and outcomes were discounted annually at 3%. Costs are presented in 2006 Australian dollars (AUD) (currency exchange: 1 AUD = 0.74 USD). RESULTS--The mean number of years in diabetes remission over a lifetime was 11.4 for surgical therapy patients and 2.1 for conventional therapy patients. Over the remainder of their lifetime, surgical and conventional therapy patients lived 15.7 and 14.5 discounted QALYs, respectively. The mean discounted lifetime costs were 98,900 AUD per surgical therapy patient and 101,400 AUD per conventional therapy patient. Relative to conventional therapy, surgically induced weight loss was associated with a mean health care saving of 2,400 AUD and 1.2 additional QALYs per patient. CONCLUSIONS--Surgically induced weight loss is a dominant intervention (it both saves health care costs and generates health benefits) for managing recently diagnosed type 2 diabetes in class IBI obese patients in Australia. <br /

Are Surgical Trials with Negative Results Being Interpreted Correctly?

BACKGROUND: Many published accounts of clinical trials report no differences between the treatment arms, while being underpowered to find differences. This study determined how the authors of these reports interpreted their findings. STUDY DESIGN: We examined 54 reports of surgical trials chosen randomly from a database of 110 influential trials conducted in 2008. Seven that reported having adequate statistical power (b 0.9) were excluded from further analysis, as were the 32 that reported significant differences between the treatment arms. We examined the remaining 15 to see whether the authors interpreted their negative findings appropriately. Appropriate interpretations discussed the lack of power and/or called for larger studies. RESULTS: Three of the 7 trials that did not report an a priori power calculation offered inappropriate interpretations, as did 3 of the 8 trials that reported an a priori power < 0.90. However, we examined only a modest number of trial reports from 1 year. CONCLUSIONS: Negative findings in underpowered trials were often interpreted as showing the equivalence of the treatment arms with no discussion of the issue of being underpowered. This may lead clinicians to accept new treatments that have not been validated

Cost-Efficacy of Surgically Induced Weight Loss for the Management of Type 2 Diabetes: A randomized controlled trial

OBJECTIVE -- To determine the within-trial cost-efficacy of surgical therapy relative to conventional therapy for achieving remission of recently diagnosed type 2 diabetes in class I and II obese patients. RESEARCH DESIGN AND METHODS -- Efficacy results were derived from a 2-year randomized controlled trial. A health sector perspective was adopted, and within-trial intervention costs included gastric banding surgery, mitigation of complications, outpatient medical consultations, medical investigations, pathology, weight loss therapies, and medication. Resource use was measured based on data drawn from a trial database and patient medical records and valued based on private hospital costs and government schedules in 2006 Australian dollars (AUD). An incremental cost-effectiveness analysis was undertaken. RESULTS -- Mean 2-year intervention costs per patient were 13,400 AUD for surgical therapy and 3,400 AUD for conventional therapy, with laparoscopic adjustable gastric band (LAGB) surgery accounting for 85% of the difference. Outpatient medical consultation costs were three times higher for surgical patients, whereas medication costs were 1.5 times higher for conventional patients. The cost differences were primarily in the first 6 months of the trial. Relative to conventional therapy, the incremental cost-effectiveness ratio for surgical therapy was 16,600 AUD per case of diabetes remitted (currency exchange: 1 AUD = 0.74 USD). CONCLUSIONS -- Surgical therapy appears to be a cost-effective option for managing type 2 diabetes in class I and II obese patients.<br /

Incidence and Risk Factors of Recurrence after Surgery for Pathology-proven Diverticular Disease

Contains fulltext : 69776.pdf (publisher's version ) (Closed access)BACKGROUND: Diverticular disease is a common problem in Western countries. Rationale for elective surgery is to prevent recurrent complicated diverticulitis and to reduce emergency procedures. Recurrent diverticulitis occurs in about 10% after resection. The pathogenesis for recurrence is not completely understood. We studied the incidence and risk factors for recurrence and the overall morbidity and mortality of surgical therapy for diverticular disease. METHODS: Medical records of 183 consecutive patients with pathology-proven diverticulitis were eligible for evaluation. Mean duration of follow-up was 7.2 years. Number of preoperative episodes, emergency or elective surgeries, type of operation, level of anastomosis, postoperative complications, persistent postoperative pain, complications associated with colostomy reversal, and recurrent diverticulitis were noted. The Kaplan-Meier method was used to calculate the cumulative probability of recurrence. Cox regression was used to identify possible risk factors for recurrence. RESULTS: The incidence of recurrence was 8.7%, with an estimated risk of recurrence over a 15-year period of 16%. Risk factors associated with recurrence were (younger) age (p < 0.02) and the persistence of postoperative pain (p < 0.005). Persistent abdominal pain after surgery was present in 22%. Eighty percent of patients who needed emergency surgery for acute diverticulitis had no manifestation of diverticular disease prior to surgery. In addition, recurrent diverticulitis was not associated with a higher percentage of emergency procedures. CONCLUSION: Estimated risk of recurrence is high and abdominal complaints after surgical therapy for diverticulitis are frequent. Younger age and persistence of postoperative symptoms predict recurrent diverticulitis after resection. The clinical implication of these findings needs further investigation. The results of this study support the careful selection of patients for surgery for diverticulitis

Survival of patients with metastatic breast cancer: twenty-year data from two SEER registries

BACKGROUND: Many researchers are interested to know if there are any improvements in recent treatment results for metastatic breast cancer in the community, especially for 10- or 15-year survival. METHODS: Between 1981 and 1985, 782 and 580 female patients with metastatic breast cancer were extracted respectively from the Connecticut and San Francisco-Oakland registries of the Surveillance, Epidemiology, and End Results (SEER) database. The lognormal statistical method to estimate survival was retrospectively validated since the 15-year cause-specific survival rates could be calculated using the standard life-table actuarial method. Estimated rates were compared to the actuarial data available in 2000. Between 1991 and 1995, further 752 and 632 female patients with metastatic breast cancer were extracted respectively from the Connecticut and San Francisco-Oakland registries. The data were analyzed to estimate the 15-year cause-specific survival rates before the year 2005. RESULTS: The 5-year period (1981–1985) was chosen, and patients were followed as a cohort for an additional 3 years. The estimated 15-year cause-specific survival rates were 7.1% (95% confidence interval, CI, 1.8–12.4) and 9.1% (95% CI, 3.8–14.4) by the lognormal model for the two registries of Connecticut and San Francisco-Oakland respectively. Since the SEER database provides follow-up information to the end of the year 2000, actuarial calculation can be performed to confirm (validate) the estimation. The Kaplan-Meier calculation for the 15-year cause-specific survival rates were 8.3% (95% CI, 5.8–10.8) and 7.0% (95% CI, 4.3–9.7) respectively. Using the 1991–1995 5-year period cohort and followed for an additional 3 years, the 15-year cause-specific survival rates were estimated to be 9.1% (95% CI, 3.8–14.4) and 14.7% (95% CI, 9.8–19.6) for the two registries of Connecticut and San Francisco-Oakland respectively. CONCLUSIONS: For the period 1981–1985, the 15-year cause-specific survival for the Connecticut and the San Francisco-Oakland registries were comparable. For the period 1991–1995, there was not much change in survival for the Connecticut registry patients, but there was an improvement in survival for the San Francisco-Oakland registry patients

Avoiding or Reversing Hartmann’s Procedure Provides Improved Quality of Life After Perforated Diverticulitis

# 2010 The Author(s). This article is published with open access at Springerlink.com Introduction The existing literature regarding acute perforated diverticulitis only reports about short-term outcome; longterm following outcomes have not been assessed before. The aim of this study was to assess long-term quality of life (QOL) after emergency surgery for perforated diverticulitis. Patients and Methods Validated QOL questionnaires (EQ-VAS, EQ-5D index, QLQ-C30, and QLQ-CR38) were sent to all eligible patients who had undergone emergency surgery for perforated diverticulitis in five teaching hospitals between 199