A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Impact of Sclerotinia Stem Rot on Yield of Canola

Sclerotinia sclerotiorum is the causal agent of Sclerotinia stem rot (SSR) of canola (Brassica napus). In North Dakota, the leading canola producer in the United States, SSR is an endemic disease. In order to estimate the impact of this disease on canola yield, field experiments were conducted from 2000 to 2004 at several locations in North Dakota and Minnesota. Experimental plots were either inoculated with laboratory-produced ascospores or infected by naturally occurring inoculum in commercial fields. Applying fungicides at different concentrations and timings during the flowering period created epiphytotics of diverse intensities. Disease incidence was measured once prior to harvesting the crop on 50 to 100 plants per plot. Results of the study indicated that 0.5% of the potential yield (equivalent to 12.75 kg/ha) was lost for every unit percentage of SSR incidence (range of 0.18 to 0.96%). Considering the current cost of fungicide applications and the market value of this commodity, a 17% SSR incidence could cause losses similar to the cost of a fungicide application. Additional efforts are required to improve current levels of tolerance of canola plants to this pathogen.

Efficacy of Fungicides for Control of Sclerotinia Stem Rot of Canola

Sclerotinia stem rot (SSR), incited by Sclerotinia sclerotiorum, causes yield reductions to canola (Brassica napus) grown in North Dakota and Minnesota. Field trials were conducted in North Dakota and Minnesota from 2000 to 2004 to evaluate the effect of foliar fungicides on SSR and canola yield. Levels of SSR varied among years and location. In general, fungicides that consistently reduced SSR incidence compared with an untreated control were azoxystrobin, benomyl, boscalid, iprodione, prothioconazole, tebuconazole, thiophanate-methyl, trifloxystrobin, and vinclozolin. Significant reductions in SSR incidence with fungicides did not always translate into differences in canola yield, however. Inconsistent results were observed with different timings of applications based on percent bloom. This indicates that application timing should be based on factors in addition to percent bloom.

A pilot study of the continuous glucose monitoring system: clinical decisions and glycemic control after its use in pediatric type 1 diabetic subjects

OBJECTIVE

To determine whether the continuous glucose monitoring system (CGMS) (MiniMed, Sylmar, CA) could be used to make clinical decisions and whether it has an impact on glycemia in pediatric type 1 diabetic subjects.

RESEARCH DESIGN AND METHODS

Pediatric subjects were recruited if they had HbA(1c) >8.0% with management problems (n = 35) or episodes of severe or nocturnal hypoglycemia or hypoglycemia unawareness associated with HbA(1c) < or =8.0% (n = 12). A total of 47 patients with a mean HbA(1c) value of 8.6 +/- 1.6% (mean age 11.8 +/- 4.6 years, youngest 2.7 years, and diabetes duration 5.5 +/- 3.5 years) on three to four insulin injections/day (n = 24) or insulin pump therapy (n = 23) were followed with the CGMS for a mean of 69.5 +/- 28 h. Comparisons were made between the number of high (>150 mg/dl) and low (<70 mg/dl) glucose patterns discerned with the sensor or the logbook, and HbA(1c) levels were evaluated.

RESULTS

In patients on injection therapy, 30 high or low glucose patterns were discerned with the logbook records and 120 patterns with the CGMS. Specific alterations of the diabetes regimen were made. An overall significant change in HbA(1c), from 3 months before wearing the sensor to 6 months after (analysis of variance 0.04), was found in the subjects. Post hoc analysis showed a significant change in HbA(1c) from 8.6 +/- 1.5% at baseline to 8.4 +/- 1.3% at 3 months (paired Student's t test 0.03).

CONCLUSIONS

The CGMS can be used by pediatric patients to detect abnormal patterns of glycemia. The information that was obtained could be used to alter the diabetes regimen and impact glycemic outcome.

Use of insulin pump therapy at nighttime only for children 7-10 years of age with type 1 diabetes

OBJECTIVE

Because of age-related developmental and cognitive issues, children <10 years of age may not be able to wear an insulin pump safely when they are not under direct parental supervision. The purpose of this study was to determine if insulin pump therapy at nighttime only, when children are at home, could improve fasting and nighttime blood glucose levels without adverse effects.

RESEARCH DESIGN AND METHODS

The study cohort consisted of 10 children aged 7-10 years. A randomized crossover design was used to compare nighttime-only pump usage from dinner and throughout the night, combined with a prebreakfast injection of intermediate-acting NPH and rapid-acting lispro insulin, with 3 insulin injections per day. Comparisons were made among mean blood glucose values and percentage of blood glucose levels within the target range (70-150 mg/dl) before meals, at bedtime, and at 3:00 A.M.; serum fructosamine levels; and scores on measures of adherence and fear of hypoglycemia.

RESULTS

Compared with baseline levels, the use of the pump resulted in a significant decrease in the mean average (P < 0.001), breakfast (P < 0.0001), and 3:00 A.M. (P < 0.003) blood glucose levels. There was a decrease in the percentage of blood glucose values less than the target range (P < 0.01) and in fructosamine (P < 0.01) values and an increase in the percentage of blood glucose levels within the target range (P < 0.03).

CONCLUSIONS

Nighttime-only insulin pump therapy may be a viable alternative that young children can use to improve glycemia when they are not capable of independently managing an insulin pump.

Insulin pump therapy in type 1 pediatric patients: now and into the year 2000

There are a number of medical conditions such as growth failure in children, pregnancy, lipid abnormalities, and early complications that are improved by the meticulous glycemic control that can be achieved with insulin pump therapy (CSII). By using an insulin pump, many patients with severe hypoglycemia, the dawn phenomenon, extremes of glycemic excursion, recurrent diabetic ketoacidosis (DKA) and hypoglycemia unawareness have amelioration of these problems. However, pump therapy involves problems such as weight gain, recurrent ketosis due to pump failure, infections, and risk of hypoglycemia. Owing to many developmental issues, young children may not be able to wear the pump without parental supervision. We have used the pump at night time only in these patients. This has allowed children of 7-10 years of age to benefit from improved nocturnal glycemia without the risk of pump therapy when they are without an adult to help. We have also used the pump in subjects with recurrent DKA and in our general patient population (mean age 13.6+/-3.9 years). In our pump cohort, CSII led to improvement in quality of life, knowledge, adherence, and responsibility. A reduction in hypoglycemia, DKA rate and mean HbA(1c) was associated with pump usage. For this to occur, however, pump education must be geared to the pediatric subject and his/her family. Education materials and tools help in learning how to use the pump and how to deal with the intricacies of basal and bolus dosing, and the effect of exercise, food and illness on diabetes management. The pump has improved since it was first introduced and these modifications have made it easier, more painless and less hazardous. With the development of continuous glucose sensors and implantable pumps, the next century will see pump therapy lead to the artificial pancreas.

The treatment and prevention of diabetic ketoacidosis in children and adolescents with type I diabetes mellitus

There remain a number of important controversies in the management of pediatric DKA. From the sodium content of the hydrational fluid to the rate of fluid administration that is best able to reverse the hyperosmolar dehydration attendant with DKA with minimal morbidity and mortality, there is no universal agreement on how patients with this devastating metabolic disturbance should be treated. It is still unclear what promotes or protects patients from neurologic insult during DKA reversal. It is appropriate to begin to develop a national approach to eradicating DKA. This would require widespread public and professional education programs aimed at detecting new-onset type I patients prior to the onset of DKA. It would involve promoting diabetes screening programs aimed at detecting patients before the onset of symptomatic disease, and these would most appropriately be centered in the pediatrician's office. In the known patient, DKA still occurs as the result of intercurrent illness and nonadherence to the diabetes regimen due to patient or family chaos and dysfunction. Clearly, more strategies are needed to address these psychological and family patterns and the fact that many tenuous families have insufficient access to appropriate medical care. Those caring for children and adolescents must do all they can to prevent DKA and to treat it optimally to avert the toll this metabolic aberration takes on the pediatric diabetes population.

Insulin pump therapy in type 1 pediatric patients: now and into the year 2000

There are a number of medical conditions such as growth failure in children, pregnancy, lipid abnormalities, and early complications that are improved by the meticulous glycemic control that can be achieved with insulin pump therapy (CSII). By using an insulin pump, many patients with severe hypoglycemia, the dawn phenomenon, extremes of glycemic excursion, recurrent diabetic ketoacidosis (DKA) and hypoglycemia unawareness have amelioration of these problems. However, pump therapy involves problems such as weight gain, recurrent ketosis due to pump failure, infections, and risk of hypoglycemia. Owing to many developmental issues, young children may not be able to wear the pump without parental supervision. We have used the pump at night time only in these patients. This has allowed children of 7-10 years of age to benefit from improved nocturnal glycemia without the risk of pump therapy when they are without an adult to help. We have also used the pump in subjects with recurrent DKA and in our general patient population (mean age 13.6+/-3.9 years). In our pump cohort, CSII led to improvement in quality of life, knowledge, adherence, and responsibility. A reduction in hypoglycemia, DKA rate and mean HbA(1c) was associated with pump usage. For this to occur, however, pump education must be geared to the pediatric subject and his/her family. Education materials and tools help in learning how to use the pump and how to deal with the intricacies of basal and bolus dosing, and the effect of exercise, food and illness on diabetes management. The pump has improved since it was first introduced and these modifications have made it easier, more painless and less hazardous. With the development of continuous glucose sensors and implantable pumps, the next century will see pump therapy lead to the artificial pancreas.

Use of a plastic insulin dosage guide to correct blood glucose levels out of the target range and for carbohydrate counting in subjects with type 1 diabetes

OBJECTIVE

To improve glycemic control, a hand-held plastic Insulin Dosage Guide was developed to correct blood glucose levels outside of the target range.

RESEARCH DESIGN AND METHODS

Protocol 1: Some 40 children (mean age 10.6+/-4.6 years) were randomly assigned for 3 months to use a written-on-paper algorithm or the Insulin Dosage Guide to correct abnormal blood glucose levels. Mean HbA1c and blood glucose levels and time to teach insulin dosage correction were compared. Protocol 2: The Insulin Dosage Guide was used by 83 subjects (mean age 11.4+/-4.3 years) for 1 year, and mean HbA1c levels, blood glucose levels, and number of consecutive high blood glucose values taken before and after the year were compared. Protocol 3: Some 20 patients (mean age 10.1+/-3.7 years) using rapid-acting insulin and 64 patients (mean age 15.9+/-3.6 years) using an insulin pump and rapid-acting insulin used the Insulin Dosage Guide and had mean blood glucose levels, HbA1c, and percentage of blood glucose levels outside of the target range determined.

RESULTS

Protocol 1: There was a significant reduction in mean HbA1c (P = 0.04) and blood glucose levels (P = 0.05) and in the time needed to teach how to correct blood glucose values using the Insulin Dosage Guide compared with the paper algorithm. Protocol 2: There was a decrease in mean HbA1c levels (P = 0.0001) and a decrease in the mean number of consecutive blood glucose levels (P = 0.001) over the 1-year time period. Protocol 3: With rapid-acting insulin, there was a significant increase in the percentage of blood glucose levels within the target range (1 month, P = 0.04; at 3 months, P = 0.03). With the insulin pump, there was a high rate (90%) of blood glucose levels in the target range during pump initiation when the Insulin Dosage Guide was used.

CONCLUSIONS

This inexpensive hand-held plastic card, which is portable and easy to use, may help patients improve glycemia and successfully manage diabetes.

Association between diabetes control and visits to a multidisciplinary pediatric diabetes clinic

OBJECTIVE

To determine if there is a relationship between diabetes outcome as measured by HbA1C and the number of multidisciplinary clinic visits per year in children and youth with diabetes.

RESEARCH DESIGN AND METHODS

The number of clinic visits per year, the mean HbA1C (by DCA 2000, Miles, Tarrytown, NY), type of insurance, parental marital status, parental age, maximal parental grade level achieved, family income, self-identified race, and scores on adherence and knowledge tests were compared for 1995 in 360 patients with a mean age of 11.6 +/- 4.8 years (1-2 visits, 85 patients; 3-4 visits, 275 patients), for 1996 in 412 patients with a mean age of 11.6 +/- 4.7 years (1-2 visits, 115 patients; 3-4 visits, 297 patients), and for 1997 in 442 patients with a mean age of 11.8 +/- 4.9 years (1-2 visits, 126 patients; 3-4 visits, 332 patients).

RESULTS

There was a significant difference in the mean HbA1C levels between subjects with 1 to 2 visits versus 3 to 4 visits during the 3 years of this study. In 1995, the mean HbA1C was 9.0 +/- 2.0% for subjects with 1 to 2 visits and 8.3 +/- 1.6% for subjects with 3 to 4 visits. In 1996, the mean HbA1C was 9.3 +/- 2.0% for subjects with 1 to 2 visits and 8.4 +/- 1.6% in those with 3 to 4 visits, whereas in 1997, the mean HbA1C was 9.1 +/- 1.9% with 1 to 2 visits and 8.3 +/- 1.5% with 3 to 4 visits. There was a significant difference in the number of visits by the age of the subject. The mean age of patients with 1 to 2 visits was 13.6 +/- 4.5 years; it was 10.8 +/- 4.6 years with 3 to 4 visits. However, for age groups <13 years versus >/=13 years, there was still a difference between HbA1C levels for subjects with 1 to 2 visits compared with 3 to 4 visits (8.9 +/- 1.7% versus 8.1 +/- 1.3%, respectively). The only patient/family characteristic that had an association with number of visits was the marital status of the parents. Children from single-parent households had fewer visits. There was no association between health insurance status and number of visits and there was no difference between the number of visits and the mean scores on tests of adherence or knowledge. Multivariate analysis showed that the number of visits was a significant predictor of HbA1C even after controlling for age, duration of diabetes, and scores on adherence and knowledge tests.

CONCLUSIONS

The finding that subjects with more frequent visits to a multidisciplinary diabetes clinic had lower HbA1C levels during the 3 years of this study suggests that strategies should be developed to promote adherence with quarterly visits, particularly targeted to children from single-parent households and to teens.

Neurocognitive functioning in children diagnosed with diabetes before age 10 years

Our objective was to determine scores on tests of neurocognitive functioning in children diagnosed with diabetes before age 10 years and to determine the association of age of diagnosis, duration of diabetes, subtle hypoglycemia, severe hypoglycemia, and history of hypoglycemic seizures with these neurocognitive test scores. Fifty-five of 62 eligible patients with a mean age of 7.9 +/- 1.6 years followed in our center were given the Woodcock-Johnson Psychoeducational Battery, Beery Developmental Test of Visual-Motor Integration, Finger Tapping, Grooved Pegboard, and Verbal Selective Reminding tests to evaluate the following domains: memory/attention, visual-perceptual, broad cognitive function, academic achievement, and fine motor speed/coordination. Fifteen age-matched siblings served as controls. Twenty-seven subjects were less than 5 years of age when diagnosed with diabetes, the mean age at diagnosis was 4.5 +/- 2.1 years of age, and mean diabetes duration was 2.6 +/- 2.0 years. Eighteen patients had a history of severe hypoglycemia, eight of whom had hypoglycemic seizures. The mean HbA1c was 7.8 +/- 1.1% for the year prior to testing. Our results showed that the overall mean scores for the extensive neurocognitive battery were within the normal range and were comparable to the scores of the age-matched sibling controls. Age of diagnosis and duration of diabetes did not relate to neurocognitive test results. Mean HbA1c had a negative association with some tests of memory/attention (p < 0.03-0.04) and academic achievement (p < 0.005-0.03), while number of blood glucose levels less than mg/dL had a positive association with memory/attention (p < 0.004-0.04), verbal comprehension (p < 0.03) and academic achievement (p < 0.018-0.05). There was no association of neurocognitive test scores with severe hypoglycemia, but subjects with history of hypoglycemic seizures had a decrease in scores on tests assessing memory skills (p < 0.03) including short term memory and memory for words. These data suggest that overall neurocognitive test scores were within the normal range and comparable to controls. However, specific aspects of neurocognitive functioning may be adversely affected by having had a hypoglycemic seizure, but not by episodes of severe hypoglycemia without seizure. Lower HbA1c and an increase in the number of blood glucose levels less than 70 mg/ dL (subtle hypoglycemia) which were associated with higher scores in some domains of academic achievement and memory suggests that stable glycemia may influence cognitive abilities and/or that successful diabetes management requires cognitive skills. Strategies to diminish the risk of seizures with hypoglycemia should be investigated.

Evaluation of a snack bar containing uncooked cornstarch in subjects with diabetes

The objective of this study was to determine the effect of a snack bar containing uncooked cornstarch, equivalent to 1 1/2 starch/bread exchanges (bar 1), compared to a control bar (bar 2), on the incidence of nocturnal and morning hypoglycemia in subjects with diabetes. Adolescent campers and counselors with diabetes (n = 79) were randomly assigned to Group A (5 nights of snack bar 1 as the evening snack, followed by 5 nights of snack bar 2) or Group B (5 nights of snack bar 2 as the evening snack, followed by 5 nights of snack bar 1). Midnight and morning finger stick blood glucose levels were compared to determine the incidence of hypoglycemia (< 60 mg/dl) and hyperglycemia (> 250 mg/dl), and events were analyzed for the total cohort, Group A, and Group B and by glycated hemoglobin quartile to determine the effect of each bar on glycemia. For subjects with diabetes there was a significant decrease in the number of hypoglycemic episodes with bar 1 compared to bar 2 at midnight (total cohort and Groups A and B) and in the morning (total cohort and Group A). There was a significant decrease in the number of subjects to ever experience hypoglycemia with snack bar 1 compared to snack bar 2, a significantly lower incidence of hyperglycemic episodes at midnight with snack bar 1, and no difference in the incidence of hypoglycemia by glycated hemoglobin quartile. These data suggest that the snack bar containing uncooked cornstarch can diminish night time and morning hypoglycemia in subjects with diabetes, without causing hyperglycemia.

A randomized, blinded trial of uncooked cornstarch to diminish nocturnal hypoglycemia at diabetes camp

OBJECTIVE

To determine if uncooked cornstarch, as part of the evening snack, can avert nocturnal hypoglycemia in type 1 diabetes.

RESEARCH DESIGN AND METHODS

Fifty-one campers and counselors at the American Diabetes Association Camp in San Bernardino, CA were randomly assigned to receive 5 g of uncooked cornstarch as part of the 21:00 evening snack vs. a standard snack of equivalent carbohydrate content. Each snack was given for five nights and the participants and medical personnel were blinded as to assignment. Midnight and 07:00 finger stick blood glucose levels were compared with values <60 mg/dl defined as hypoglycemia and values > 250 mg/dl defined as hyperglycemia.

RESULTS

There were 218 midnight and 222 07:00 values for comparison. There were six episodes of hypoglycemia at midnight and nine episodes of hypoglycemia at 07:00 for the cornstarch snack nights vs. 30 hypoglycemia episodes at midnight and 21 at 07:00 for the standard snack nights (P < 0.001 and <0.05, respectively). There was no difference in the number of hyperglycemic events at midnight or 07:00 for the cornstarch vs. standard snack nights. At midnight, 12% of campers had hypoglycemia after the cornstarch snack vs. 46% after the standard snack (P < 0.001), and at 07:00, 16% had hypoglycemia after cornstarch vs. 26% after the standard snack (P = 0.327).

CONCLUSIONS

These data suggest that uncooked cornstarch, as part of the evening snack, can diminish the nighttime and morning hypoglycemia associated with type 1 diabetes, without causing hyperglycemia.

Pediatric nurses: the assessment and control of pain in preverbal infants

Pediatric nurses practicing in a children's hospital participated in this exploratory study investigating nurses' attitudes regarding postoperative pain in infants, including recognition of pain cues and strategies for pain management. Three instruments developed by us were used to obtain data: the Pain Questionnaire, a demographic and attitudinal profile; a self-directed videotape; and the Videotape Questionnaire, an interactive tool to obtain participant responses to videotaped vignettes of infants recovering from surgery. Three independent variables yielded significant results: critical care versus noncritical care nurses, agreement versus disagreement to administer pain medication to infants expected to have pain but not exhibiting pain behaviors, and classes on pediatric versus adult/pediatric pain since licensure. Noncritical care nurses, nurses agreeing to administer pain medication, and nurses attending pediatric pain classes recognized a greater number of cues on videotaped vignettes. Nurses attending pediatric pain classes administered more narcotics. Noncritical care nurses rated the pain experienced by the infants in the vignettes to be more severe compared with ratings made by critical care nurses.

Reconstitution of testosterone oxidation by purified rat cytochrome P450p (IIIA1)

Cytochrome P450p (IIIA1) has been purified from rat liver microsomes by several investigators, but in all cases the purified protein, in contrast to other P450 enzymes, has not been catalytically active when reconstituted with NADPH-cytochrome P450 reductase and dilauroylphosphatidylcholine. We now report the successful reconstitution of testosterone oxidation by cytochrome P450p, which was purified from liver microsomes from troleandomycin-treated rats. The rate of testosterone oxidation was greatest when purified cytochrome P450p (50 pmol/ml) was reconstituted with a fivefold molar excess of NADPH-cytochrome P450 reductase, an equimolar amount of cytochrome b5, 200 micrograms/ml of a chloroform/methanol extract of microsomal lipid (which could not be substituted with dilauroylphosphatidylcholine), and the nonionic detergent, Emulgen 911 (50 micrograms/ml). Testosterone oxidation by cytochrome P450p was optimal at 200 mM potassium phosphate, pH 7.25. In addition to their final concentration, the order of addition of these components was found to influence the catalytic activity of cytochrome P450p. Under these experimental conditions, purified cytochrome P450p converted testosterone to four major and four minor metabolites at an overall rate of 18 nmol/nmol P450p/min (which is comparable to the rate of testosterone oxidation catalyzed by other purified forms of rat liver cytochrome P450). The four major metabolites were 6 beta-hydroxytestosterone (51%), 2 beta-hydroxytestosterone (18%), 15 beta-hydroxytestosterone (11%) and 6-dehydrotestosterone (10%). The four minor metabolites were 18-hydroxytestosterone (3%), 1 beta-hydroxytestosterone (3%), 16 beta-hydroxytestosterone (2%), and androstenedione (2%). With the exception of 16 beta-hydroxytestosterone and androstenedione, the conversion of testosterone to each of these metabolites was inhibited greater than 85% when liver microsomes from various sources were incubated with rabbit polyclonal antibody against cytochrome P450p. This antibody, which recognized two electrophoretically distinct proteins in liver microsomes from troleandomycin-treated rats, did not inhibit testosterone oxidation by cytochromes P450a, P450b, P450h, or P450m. The catalytic turnover of microsomal cytochrome P450p was estimated from the increase in testosterone oxidation and the apparent increase in cytochrome P450 concentration following treatment of liver microsomes from troleandomycin- or erythromycin-induced rats with potassium ferricyanide (which dissociates the cytochrome P450p-inducer complex). Based on this estimate, the catalytic turnover values for purified, reconstituted cytochrome P450p were 4.2 to 4.6 times greater than the rate catalyzed by microsomal cytochrome P450p.