Saturated buffer design flow and performance in Illinois

There are few peer-reviewed studies documenting saturated buffer annual nitrate (NO₃ ) removal or that have assessed the federal practice standard design criteria. Drainage flow, NO₃ , and dissolved reactive phosphorus (DRP) were monitored at three saturated buffers in Illinois, USA, for a combined 10 site-years. Nitrate loss reduction averaged 48 ± 19% with removals of 3.5-25.2 kg NO₃ -N ha^-1 annually. Median DRP concentrations at all sampling locations were at the analytical detection limit of 0.01 mg L^-1 . The current design paradigm (i.e., USDA practice standard) prescribes there should be no flow bypassing the saturated buffer at flow rates that are ≤5% of the peak drainage system flow rate. The drainage coefficient-based and Manning's equation-based peak flow estimates were higher and lower, respectively, than the observed annual peaks in all years. This illustrated inherent uncertainty introduced early in the design process, which can be further compounded by dynamic in-buffer hydrology. The percentage of the observed peak flow rate at which bypass initiated ranged across an order of magnitude between sites (4.4-8.1% of peak flow rate at one site and 42-49% of peak at another) despite the buffers providing relatively similar NO₃ removal. Bypass at one site (SB2) was related to the concept of "antecedent buffer capacity filled," which was defined as the 5-d average water depth in the middle control structure chamber expressed as a relative percentage of the bypass stop log height. This design flow analysis serves as a call to further evaluate predictive relationships and design models for edge-of-field practices.

A quantitative understanding of the role of co-composted biochar in plant growth using meta-analysis

The combined use of biochar and compost as a soil amendment presents benefits to crops and nutrient cycling. Although there are literature reviews regarding biochar and biochar-compost mixtures, a quantitative literature review on the role of co-composted biochar (hereby called COMBI) in plant productivity is currently missing. The goal of this review paper is to find evidence-based measures of the effects of application rates, soil pH, plant types, biochar feedstock, and compost materials, on plant productivity. Plant productivity covers a variety of measurements but mostly refers to grain yield and above-ground biomass. Response ratio was selected as the effect size. Funnel plot showed that the studies were reasonably symmetrically distributed around the mean effect size. Results showed that application rates of <20 t/ha and >30 t/ha significantly increased plant productivity by 48.3 and 15.7%, respectively, while no significant yield increases were found for the application rates between 20 and 30 t/ha. When data was grouped based on the soil pH, the greatest increase in plant productivity was found to be at acidic soil pH values (pH 4-5), which was expected because the liming effect of biochar is often reported as one of the main mechanisms behind the increased crop yields. When different plant species were compared, cereal grasses grown with COMBI yielded significantly higher grain yields (39.7%). Rice husk biochar yielded the highest increase in productivity but this result was based on only one study. The second highest increase was obtained with wood-based biochars (29.4%) based on ten studies. The effect sizes found with our meta-analyses are based on 14 research works worldwide and represent the most updated information regarding the effects of COMBI on plant production. As more data on COMBI become available, data analyses can be updated to make more robust comparisons.

There's a frog in my salad! A review of online media coverage for wild vertebrates found in prepackaged produce in the United States

Prepackaged leafy green vegetables represent one of the fastest growing segments of the fresh-produce industry in the United States. Several steps in the production process have been mechanized to meet the downstream demand for prebagged lettuces. The growth in this market, however, has come with drawbacks, and chief among them are consumers finding wild animals in prepackaged crops. These incidents may signal an overburdened produce supply chain, but we currently lack the information needed to determine if this is a food-safety problem or food-quality concern. Here, we address this gap by reviewing online media coverage of wild vertebrates found in prepackaged produce items by customers in the United States. We discovered 40 independent incidents since 2003 with 95% having occurred during 2008-2018, suggesting that the frequency of incidents may have increased during the last decade. The minority of incidents included wild animals found in organic produce (27.5%), whereas the majority involved conventionally grown crops (72.5%). Most incidents involved amphibians (52.5%) and reptiles (22.5%), while fewer contained mammals (17.5%) and birds (7.5%). Frogs and toads made up all of the amphibian-related incidents, with more than 60% comprising small-bodied treefrogs found in various types of fresh leafy greens. At least seven incidents involved Pacific Treefrogs (Hyliola regilla) and three comprised Green Anoles (Anolis carolinensis). One lizard and nine frogs were found alive, and at least two frogs were released into non-native areas. This is the first review quantifying incidents of vertebrates found by customers in prepackaged produce, yet it remains unclear whether these occurrences indicate a food-safety crisis or a complaint against food quality. Nevertheless, wild animals can spread diseases to humans via contaminated produce, therefore we contend that industry professionals can reduce the potential health risk to their consumers and negative economic consequences to themselves through increased attention to this matter.

Modeling effect of cover condition and soil type on rotavirus transport in surface flow

Runoff from animal production facilities contains various microbial pathogens which pose a health hazard to both humans and animals. Rotavirus is a frequently detected pathogen in agricultural runoff and the leading cause of death among children around the world. Diarrheal infection caused by rotavirus causes more than two million hospitalizations and death of more than 500,000 children every year. Very little information is available on the environmental factors governing rotavirus transport in surface runoff. The objective of this study is to model rotavirus transport in overland flow and to compare the model results with experimental observations. A physically based model, which incorporates the transport of infective rotavirus particles in both liquid (suspension or free-floating) and solid phase (adsorbed to soil particles), has been used in this study. Comparison of the model results with experimental results showed that the model could reproduce the recovery kinetics satisfactorily but under-predicted the virus recovery in a few cases when multiple peaks were observed during experiments. Similarly, the calibrated model had a good agreement between observed and modeled total virus recovery. The model may prove to be a promising tool for developing effective management practices for controlling microbial pathogens in surface runoff.

Improving Hyperglycemia Management in the Intensive Care Unit

Purpose

The purpose of this study was to assess the feasibility of a nurse-driven effort to improve hyperglycemia management in the intensive care unit (ICU) setting.

Methods

The setting was the ICU of a large urban hospital. The program was composed of 3 components: nurses as leaders, a clinical pathway to identify patients in need of hyperglycemia therapy, and implementation of a redesigned insulin infusion algorithm (the Columnar Insulin Dosing Chart). Time to reach a target glucose range of 80 to 110 mg/dL (4.4-6.1 mmol/L) was evaluated.

Results

One hundred sixteen ICU nurses were trained in the project. The Columnar Insulin Dosing Chart was applied to 20 patients. The average time required to reach the target blood glucose range was 12.8 hours. Below-target blood glucose levels were 6.9% of all blood glucose levels recorded, but only 0.9% were below 60 mg/dL (3.3 mmol/L). There was no sustained hypoglycemia, and no persistent clinical findings attributable to hypoglycemia were noted. Barriers to implementing the project included an increased nursing workload, the need for more finger-stick blood glucose monitors, and the need to acquire new finger-lancing devices that allowed for shallower skin puncture and increased patient comfort.

Conclusions

Tighter glycemic control goals can be attained in a busy ICU by a nurse-led team using a pathway for identifying and treating hyperglycemia, clear decision support tools, and adequate nurse education. The novel chart based insulin infusion algorithm chosen as the standard for this pilot was an effective tool for reducing the blood glucose to target range with no clinically significant hypoglycemia.

Effects of formulation on transport of pyrethroids in residential settings

Washoff of 17 pyrethroid products resulting from a 1-h, 25.4-mm rainfall occurring 24 h after application was measured in indoor studies with concrete slabs. These products included different pyrethroid active ingredients and a range of formulation types. Based on this replicated study, 5 product pairs with contrasting washoff behaviors were chosen for an outdoor study using 6 full-scale house fronts in central California. Products in 4 of these pairs were applied once to different rectangular areas on the driveway (1 product in each pair to 3 house lots and the other to the remaining 3 house lots). The products in the fifth pair were applied 3 times at 2-mo intervals to vertical stucco walls above the driveway. All house lots received natural and simulated rainfall over 7 mo. Indoor studies showed differences up to 170-fold between paired products, whereas the maximum difference between paired products in the field was only 5-fold. In the pair applied to the wall, 1 product had 91 times the washoff of the other in the indoor study, whereas in the field the same product had 15% lower washoff. These results show that, although the formulation may influence washoff under actual use conditions, its influence is complex and not always as predicted by indoor experiments. Because the formulation also affects insect control, washoff research needs to be conducted together with efficacy testing.

Major transport mechanisms of pyrethroids in residential settings and effects of mitigation measures

The major pathways for transport of pyrethroids were determined in runoff studies conducted at a full-scale test facility in central California, USA. The 6 replicate house lots were typical of front lawns and house fronts of California residential developments and consisted of stucco walls, garage doors, driveways, and residential lawn irrigation sprinkler systems. Each of the 6 lots also included a rainfall simulator to generate artificial rainfall events. Different pyrethroids were applied to 5 surfaces—driveway, garage door and adjacent walls, lawn, lawn perimeter (grass near the house walls), and house walls above grass. The volume of runoff water from each house lot was measured, sampled, and analyzed to determine the amount of pyrethroid mass lost from each surface. Applications to 3 of the house lots were made using the application practices typically used prior to recent label changes, and applications were made to the other 3 house lots according to the revised application procedures. Results from the house lots using the historic application procedures showed that losses of the compounds applied to the driveway and garage door (including the adjacent walls) were 99.75% of total measured runoff losses. The greatest losses were associated with significant rainfall events rather than lawn irrigation events. However, runoff losses were 40 times less using the revised application procedures recently specified on pyrethroid labels.

A comparison study of continuous insulin infusion protocols in the medical intensive care unit: computer-guided vs. standard column-based algorithms

PURPOSE

To compare the safety and efficacy of continuous insulin infusion (CII) via a computer-guided and a standard paper form protocol in a medical intensive care unit (ICU).

METHODS

Multicenter randomized trial of 153 ICU patients randomized to CII using the Glucommander (n = 77) or a standard paper protocol (n = 76). Both protocols used glulisine insulin and targeted blood glucose (BG) between 80 mg/dL and 120 mg/dL.

RESULTS

The Glucommander resulted in a lower mean BG value (103 ± 8.8 mg/dL vs. 117 ± 16.5 mg/dL, P < 0.001) and in a shorter time to reach BG target (4.8 ± 2.8 vs.7.8 hours ± 9.1 hours, P < 0.01), and once at target resulted in a higher percentage of BG readings within target (71.0 ± 17.0% vs. 51.3 ± 19.7%, P < 0.001) than the standard protocol. Mean insulin infusion rate in the Glucommander was similar to the standard protocol (P = 0.12). The percentages of patients with ≥1 episode of BG <40 mg/dL and <60 mg/dL were 3.9% and 42.9% in the Glucommander and 5.6% and 31.9% in the standard, respectively [P = not significant (NS)]. Repeated measures analyses show that the probabilities of BG reading <40 mg/dL or <60 mg/dL were not significantly different between groups (P = 0.969, P = 0.084) after accounting for within-patient correlations with or without adjusting for time effect. There were no differences between groups in the length of hospital stay (P = 0.704), ICU stay (P = 0.145), or inhospital mortality (P = 0.561).

CONCLUSION

Both treatment algorithms resulted in significant improvement in glycemic control in critically ill patients in the medical ICU. The computer-based algorithm resulted in tighter glycemic control without an increased risk of hypoglycemic events compared to the standard paper protocol.

Use of a computerized intravenous insulin algorithm within a nurse-directed protocol for patients undergoing cardiovascular surgery

BACKGROUND

Several studies have shown the benefits of tight glycemic control in the intensive care unit. A large hospital became concerned about certain deficiencies in the management of glucose control in conjunction with cardiovascular surgery. A multidisciplinary steering committee was formed, which implemented a glycemic protocol, the subject of this study.

METHODS

The glycemic protocol is a perioperative, nurse-directed program that incorporates the computerized intravenous (IV) insulin algorithm, Glucommander. Upon admission, hemoglobin A1c and blood glucose (BG) were tested, and patients were screened for previously diagnosed diabetes. This information was used to determine if preoperative insulin will be used, if the patient will be transitioned post-IV to subcutaneous (SC) basal-bolus insulin, and if insulin will be prescribed on discharge. IV insulin was initiated perioperatively in known diabetes cases or if one BG value >140 mg/dl or two BG values >110 mg/dl within 24 hours before or during surgery. The target range was 90 to 120 mg/dl.

RESULTS

In the 9 months after protocol implementation, 93% of the patients had no BG value >200 mg/dl during the first 48 hours postoperatively. In the 6 months of study data, there were 457 patients. The mean time to target range was 3.0 hours. The mean IV insulin run time was 37 hours. The mean BG value was 107 mg/dl. Only 2% of patients had transient BG <50 mg/dl, and no BG values were <40 mg/dl. Of the patients, 52% were transitioned to SC basal-bolus, and 26% were discharged on insulin.

CONCLUSIONS

The Glucommander earned high respect from the nurses for the way it scheduled BG tests and eliminated the calculation time and calculation errors associated with manual methods. The protocol was highly effective in normalizing glucose without hypoglycemia. The multidisciplinary steering committee proved to be a good approach to implementing a glycemic protocol.

A cause-and-effect-based mathematical curvilinear model that predicts the effects of self-monitoring of blood glucose frequency on hemoglobin A1c and is suitable for statistical correlations

BACKGROUND

Previous studies have shown an association between the frequency of self-monitored blood glucose (SMBG) and hemoglobin A1c. Randomized controlled trials (RCTs) have shown this to be a causal correlation for insulin-using patients. Several studies have used linear regression, but a straight line will descend into negative hemoglobin A1c values (an impossibility). This study developed a cause-and-effect-based nonlinear model to predict the outcome of RCTs on this subject, tested this model with clinical data, and offered this model in place of linear regression, especially for the still-debated case of noninsulin-using patients.

METHODS

The model was developed from cause-and-effect principles. The clinical study utilized retrospective data from patient histories of a large endocrine practice. Data sets were obtained for five treatment regimens: continuous subcutaneous insulin infusion (CSII), subcutaneous insulin (SC), no insulin (NI), oral medication (OM), and no medication (NM). OM and NM are subgroups of NI. The model was fitted to each group using nonlinear leastsquares methods. Each group was ordered by SMBG tests per day (BGpd) and was divided in half; t tests were run between the A1C's of the two halves.

RESULTS

Self-monitored blood glucose readings from 1255 subjects were analyzed (CSII, N = 417; SC, N = 286; NI, N = 552; OM, N = 505; NM, N = 47). The CSII, SC, NI, and OM groups showed the expected declining statistically fitted curve and a significant association of BGpd with hemoglobin A1c (P < 0.004). The NM group showed insignificant results.

CONCLUSIONS

The nonlinear model is based on cause-and-effect principles and mathematics. It yields a prediction that RCTs will be able to reveal that higher SMBG frequency causes lower hemoglobin A1c.

Working to improve care of hospital hyperglycemia through statewide collaboration: the Georgia Hospital Association Diabetes Special Interest Group

OBJECTIVE

To review the efforts of the Georgia Hospital Association Diabetes Special Interest Group (DSIG) to develop and disseminate sample clinical guidelines on management of inpatient hyperglycemia.

METHODS

Beginning in February 2003, a consortium of physicians and allied health professionals from throughout the state of Georgia began meeting on a frequent basis to formulate a plan to enhance the care of hospitalized patients with hyperglycemia. The immediate goals of the DSIG were the identification and organization of interested stakeholders, the development of consensus sample clinical guidelines, and the dissemination of information.

RESULTS

Since its inception, the DSIG has accomplished the following: development of 7 consensus sample clinical guidelines, construction of a Web site that posts these clinical guidelines and other useful related information and educational materials, and sponsorship of workshops throughout the state of Georgia.

CONCLUSION

As the importance of glucose control in the hospital setting has become increasingly recognized, institutions must find ways of applying results of clinical trials to "real-world" hospital environments. The DSIG is an example of a successful collaboration that could serve as a model for other state hospital organizations that wish to develop programs to enhance the care of inpatients with hyperglycemia.

Glucommander: a computer-directed intravenous insulin system shown to be safe, simple, and effective in 120,618 h of operation

OBJECTIVE

Intravenous insulin is now the recommended method of diabetes management in critically ill persons in the hospital. The published methods for administering the insulin are complex and are usually limited to intensive care units with a low patient-to-nurse ratio.

RESEARCH DESIGN AND METHODS

A computer-directed algorithm for advice on the delivery of intravenous insulin that is flexible in blood glucose timing and advises insulin dosing in a graduated manner has been developed. This software program, known as the Glucommander, has been used extensively by our group. The data were analyzed for this study.

RESULTS

The data from 5,080 intravenous insulin runs over 120,683 h show that blood glucose levels can be safely stabilized in a target range without significant hypoglycemia by nonspecialized nurses working on any unit of a general hospital. The mean glucose level reached <150 mg/dl in 3 h. Only 0.6% of all glucose values were <50 mg/dl. The prevalence of hypoglycemia <40 mg/dl was 2.6% of all runs. No hypoglycemia was severe.

CONCLUSIONS

This computer-directed algorithm is a simple, safe, effective, and robust method for maintaining glycemic control. It has been extensively studied and is applicable in a wide variety of conditions. In contrast to other published intravenous insulin protocols, which have been limited to intensive care units, Glucommander can be used in all units of any hospital.

Intravenous Insulin Infusion Therapy: Indications, Methods, and Transition to Subcutaneous Insulin Therapy

OBJECTIVE

To describe indications for intravenous (IV) insulin infusion therapy and glycemic thresholds, discuss methods and protocols, and promote use of and access to IV insulin infusion therapy for all appropriate patients in the hospital setting.

RESULTS

Randomized, prospectively designed trials support the use of IV insulin infusion therapy for patients in the surgical intensive-care unit, including postoperative cardiac patients and patients having myocardial infarction. Among patients in the surgical intensive-care unit, reanalysis of the data suggested no threshold at which benefit occurred above the blood glucose level of 110 mg/dL. In another study, retrospective analysis of data among critically ill medical and surgical patients suggested a target blood glucose level of 145 mg/dL or less. In other populations, the threshold or ideal target blood glucose range has not been determined. Three protocols for IV insulin infusion are described that maintain blood glucose levels safely below the upper limit of their respective target ranges without substantial risk of hypoglycemia.

CONCLUSION

The threshold for initiation of IV insulin infusion is 110 mg/dL for critically ill surgical patients, 140 mg/dL for other medical or surgical patients, 180 mg/dL for patients in whom subcutaneous insulin regimens fail, and 100 mg/dL for pregnant women. The blood glucose target range is 80 to 110 mg/dL for selected critically ill surgical patients, 70 to 100 mg/dL for pregnant women, and 90 to 140 mg/dL for all other patients. Hospitals should develop procedures to make IV insulin infusion therapy available to all appropriate patients.

Insulin pump therapy in the 21st century. Strategies for successful use in adults, adolescents, and children with diabetes

Intensive diabetes management can be achieved in adults, adolescents, and children with use of CSII. Compared with MDI, CSII has better insulin pharmacokinetics, less variability in insulin absorption, and decreased risk of hypoglycemia; it also offers patients greater flexibility in lifestyle. Careful adjustment of basal and bolus doses and close follow-up, including patient education, are vital to the success of CSII.

Diabetes management in the new millennium using insulin pump therapy

Current goals of therapy of type 1 and 2 diabetes are to achieve near normal glycemia, minimize the risk of severe hypoglycemia, limit excessive weight gain, improve quality of life and delay or prevent late vascular complications. As discussed in this review, insulin pump or continuous subcutaneous insulin infusion (CSII) therapy provides a treatment option that can dramatically aid in achieving all of these goals. In comparison to multiple daily injections (MDI), CSII uses only rapid-acting insulin, provides greater flexibility in timing of meals and snacks, has programmable basal rates to optimize overnight glycemic control, can reduce the risk of exercise-induced hypoglycemia, and enhances patients' ability to control their own diabetes. Most important, in adults and adolescents with type 1 diabetes, CSII has been shown to lower HbA(1c) levels, reduce the frequency of severe hypoglycemia and limit excessive weight gain versus MDI without increasing the risk of diabetic ketoacidosis. Similarly positive results are being seen with CSII in adults with type 2 diabetes. The effectiveness of CSII and improvements in pump technology have fueled a dramatic increase in the use of this therapy. Practical guidelines are presented for selection of patients, initiation of treatment, patient education, follow-up assessments and troubleshooting. The recent introduction of methods for continuous glucose monitoring provides a new means to optimize the basal and bolus capabilities of CSII and offers the hope of the development of a feedback-controlled artificial pancreas.

What's ahead in glucose monitoring? New techniques hold promise for improved ease and accuracy

Advances in blood glucose monitoring have made it easier, more comfortable, and more practical for patients to monitor frequently. The new meters for intermittent monitoring are smaller and less dependent on technical aptitude than older models. They require less blood, and many provide downloadable information for glucose analysis. Data systems used with new meters provide valuable information that can dramatically improve glycemic control. Continuous glucose sensing (figure 4) is another major breakthrough in management of diabetes. Current systems allow only retrospective analyses, but real-time readings should be available in the near future. Such technological advances hold promise for preventing both hypoglycemia and hyperglycemia and for reducing the risk of long-term complications associated with diabetes. An artificial, mechanical islet cell may be the big next step toward bringing this disease under control. By combining continuous glucose monitoring data with continuous insulin delivery via an external or an implantable insulin pump, the outlook promises to be much brighter for patients with type 1 diabetes.

Reduction in severe hypoglycemia with long-term continuous subcutaneous insulin infusion in type I diabetes

OBJECTIVE

To compare the incidence of severe hypoglycemia in patients crossed over from multiple daily injections (MDIs) of insulin to continuous subcutaneous insulin infusion (CSII).

RESEARCH DESIGN AND METHODS

From a population of 225 patients using CSII, all patients who met the following selection criteria were included in the present study: 1) a minimum of 12 months on intensive therapy with MDIs before switching to CSII, and 2) a minimum of 12 months on CSII after crossover. Glycemic control and adverse event rates for the 1-year MDI control period were compared with those for the CSII therapy period.

RESULTS

The incidence of severe hypoglycemia during MDI therapy declined from 138 to 22 events per 100 patient-years during the 1st year of CSII (P < 0.0001) and remained significantly lower in years 2, 3, and 4 on CSII (26, 39, and 36, respectively). HbA1c levels did not change significantly between the MDI phase and any year on CSII. However, in the subgroup of patients who had pre-CSII HbA1c levels of > or = 8.0%, the change to CSII was associated with a significant reduction in HbA1c from baseline to year 1 (8.9 +/- 0.8 vs. 8.1 +/- 1.0%, P = 0.0004). The difference in diabetic ketoacidosis rates between the MDI year (14.6 events per 100 patient-years) and the CSII period (7.2 events per 100 patient-years) was not statistically significant.

CONCLUSIONS

CSII therapy was associated with a marked and sustained reduction in the rate of severe hypoglycemia without adversely affecting the level of glycemic control attained during MDI therapy. The more reproducible and flexible insulin delivery afforded by CSII was considered to be the major factor contributing to the improvement in severe hypoglycemia rates.

Evaluation of the psychosocial impact of the MiniMed variable-rate implantable insulin pump

We examined the psychosocial impact of treatment with an implantable insulin pump among persons with insulin-dependent diabetes mellitus (IDDM). Of specific interest was whether use of the MiniMed implantable insulin pump (MIP) resulted in changes in functional status, performance of diabetes self-care behavior, psychologic symptoms, and perceived level of stress. From a sample of 36 patients with IDDM, 10 persons were randomly selected to receive the MIP, while the remaining 26 served as control subjects. Additionally, a nonrandom sample of three MIP recipients from an additional site were included in the MIP group. At regular assessment intervals, all participants completed self-report questionnaires regarding psychosocial functioning and monitored blood glucose levels. After 4 months of MIP use, MIP recipients did not significantly differ from control subjects on any measure of psychosocial functioning; however, MIP use did have an impact on diabetes self-care. The MIP users monitored their blood glucose levels more frequently and had lower average blood glucose levels than control subjects. Additional follow-up is needed to determine the long-term psychosocial impact of implantable insulin pump therapy.

Synthesis and transport of glutathione by cultured human retinal pigment epithelial cells

PURPOSE

To characterize synthesis and transport of glutathione (GSH) by cultured human retinal pigment epithelial (RPE) cells.

METHODS

Cultured human RPE cells were depleted of glutathione, then incubated with various concentrations of cysteine, glutamate, and glycine or with glutathione. High-performance liquid chromatography was used to measure intracellular glutathione with time.

RESULTS

After depletion with diethylmaleate, intracellular glutathione was resynthesized from the amino acid precursors within 60 minutes. The addition of buthionine sulfoximine, a known inhibitor of GSH synthesis, completely eliminated the observed increase. Similar incubation with exogenous GSH failed to increase the intracellular GSH concentration.

CONCLUSION

Cultured human RPE cells are able to rapidly synthesize glutathione from exogenously administered amino acids, but they are incapable of direct GSH uptake.

Protection of retinal pigment epithelium from oxidative injury by glutathione and precursors

PURPOSE

This study was performed to examine the effect of exogenous glutathione (GSH) or its precursor amino acids on oxidative injury in cultured human retinal pigment epithelium (RPE).

METHODS

Cultured human RPE cells were suspended in Krebs-Henseleit medium, and 150 microM t-butylhydroperoxide was added. Cell viability was assessed by 0.2% trypan blue exclusion 30, 60, and 120 minutes after the addition of GSH or its amino acid precursors.

RESULTS

Added GSH provided protection at concentrations of 0.01 mM and higher. The amino acid precursors for GSH, glutamate, cysteine, and glycine also protected against injury, but this required at least 0.1 mM of each amino acid. Inhibition of intracellular GSH synthesis by inclusion of 1 mM buthionine sulfoximine eliminated the protection by added amino acids but did not alter the protection by added GSH.

CONCLUSIONS

These results indicate that protection by the amino acid precursors is mediated through synthesis of GSH, and they also show that exogenous GSH can provide protection against oxidative injury.

Management of posterior segment ocular trauma

Ocular trauma is a leading cause of visual impairment in the United States. Despite advances in treatment, almost half the patients with posterior, penetrating ocular injuries have permanent, severe visual loss. There is controversy with regard to the optimal role and timing of vitrectomy in the management of posterior segment injuries, as well as the proper management of magnetic intraocular foreign bodies. Improvements in surgical instrumentation and technique, combined with an increased understanding of posterior segment pathobiology, continue to modify the indications for treatment. Each of these issues is discussed in light of recent contributions to the literature.

The accuracy of glucose monitoring by diabetic individuals in their home setting

This study evaluated the accuracy of patient self- monitoring of blood glucose. Determinations were performed at home with simultaneous collec tions of whole blood into capillary tubes. Specimens were mailed to the laboratory where they were analyzed by a glucose-oxidase analyzer. A significant correlation was observed between pa tient determined and laboratory determined glucose values. However, patient-determined values differed from the laboratory values by >+20% in 53.8% of the samples. Inaccuracies were unrelated to training format, time since train ing, type of monitor, age, sex, duration of diabetes, frequency of monitor use, educational level, or knowledge of monitoring technique.

Increasing the Accuracy of Blood Glucose Values Using Visually-read Chemstrips

Four insulin-dependent diabetic adults were exposed to a feedback program designed to improve accu racy of blood glucose values obtained by patients using visually interpreted Chemstrips. Three of the four subjects demonstrated a dramatic increase in agreement between visually deter mined and reflectance photometer de termined blood glucose values follow ing exposure to the feedback treat ment. The implications of these find ings are discussed.

Blood glucose discrimination training with insulin-dependent diabetics: a clinical note

Two insulin-dependent diabetic adults were exposed to a blood glucose discrimination training program. Following baseline, during which subjects estimated their blood glucose levels twice daily, subjects received immediate feedback regarding the accuracy of their estimates. The procedure resulted in a large increase in accuracy of blood glucose level estimation. The implications of the findings were discussed.

Discrimination of blood glucose levels in insulin-dependent diabetics

Three insulin-dependent diabetic adults were exposed to a blood glucose discrimination training program. Following baseline, during which subjects estimated their blood glucose levels twice daily, subjects received immediate feedback regarding the accuracy of their estimation. The procedure resulted in a large increase in accuracy of blood glucose level estimation. The implications of the findings are discussed.

Exercise effects on fitness, lipids, glucose tolerance and insulin levels in young adults

The effect of 3 different physical training programs on cardiorespiratory (cr) fitness, fasting plasma lipids, glucose and insulin levels, and scapular skinfold thickness was assessed in 64 healthy college men. Training sessions were held 4 times a week for 5 weeks. The cr fitness improved significantly and skinfold thickness decreased following the aerobic, the pulse workout (interval training), and the anaerobic training compared to the control group. Skinfold thickness, plasma insulin, and triglyceride concentrations were significantly intercorrelated before and after training. The exercise programs had no significant effect on plasma cholesterol, triglycerides, phospholipids, glucose tolerance, or insulin levels. Change in adipose mass was thus dissociated from change in plasma insulin and triglyceride concentrations. It was concluded that in young men plasma triglycerides, the lipid component mostly readily reduced by exercise, were too low to be reduced further by a physical training program.

Effect of high- and low-fiber diets on plasma lipids and insulin

Seven healthy young adults were maintained for two separate 1-week periods on each of two very high-carbohydrate diets, one with low-fiber and one with high-fiber content. In both diets 15% of the calories were from protein, 15% from fat, and 70% were from carbohydrate. The low-fiber diet consisted of milk, glucose, and dextrins in liquid formula form, the high-fiber diet was composed of starchy foods. The crude fiber content of the high- and low-fiber diets was 18.0 and 1.0 g, respectively. The diets were isocaloric and the subjects maintained a stable weight. During the low-fiber diet the fasting triglycerides rose, reaching a peak 45% above base-line in 6 days. During the high-fiber diet the triglycerides fell to a level slightly below base-line. The cholesterol fell 16 and 23% below base-line on the low- and high-fiber diets. The glucose response to test meals representative of each diet was similar. The insulin response to a low-fiber meal was twice as great as that to a high-fiber meal containing an equivalent amount of carbohydrate. The results suggest that carbohydrate-induced hyperlipemia does not occur if the high carbohydrate diet is rich in dietary fiber, and furthermore that the insulin-stimulating potential of foods in a very high-carbohydrate diet is a critical determinant of the magnitude of carbohydrate-induced lipemia.

Advantages of a Simple Treadmill Exercise Program

Every physician knows the frustration of trying to get patients into a running program for exercise; the treadmill can be an effective alternative program.