Reducing Diabetes Burden in Medtronic's Automated Insulin Delivery Systems

Background: The MiniMed™ 780G advanced hybrid closed-loop system (MM780G) builds on the basal automation and low-glucose protection features of the MiniMed™ 670G and 770G systems. While previous publications have focused on glycemic control improvements with MM780G, burden reduction has not been fully described. Methods: Data from two 3-month pivotal trials for the MM670G with Guardian™ Sensor 3 (GS3) (104 adults; 125 children) and MM780G with Guardian™ 4 Sensor (G4S) (67 adults;109 children) were compared. Real-world data (RWD) from United States users (N = 3851) transitioning from MM770G+GS3 to MM780G+G4S were also analyzed. Analyses included a new metric for diabetes management burden (i.e., pentagon composite metric), glycemic outcomes and system burden (e.g., closed-loop exits and fingersticks per day). Results: Diabetes burden metric (-22.8% and -28.5%), time in range (+3.1% [*P = 0.035] and +6.4% [P < 0.001]) and time below range (-1.8% [*P < 0.001] and -0.7% [*P < 0.001]) significantly improved, compared to MM670G for adult and pediatric participants, respectively. The pediatric mean sensor glucose (SG) reduced by -8.6 mg/dL (*P < 0.001), while the adults' saw no change. Closed-loop use significantly increased for both cohorts (+17.1% [*P < 0.001] and +20.5% [*P < 0.001]). Closed-loop exits were significantly reduced to about 1 per week (-0.5 [*P < 0.001] and -0.7 [*P < 0.001]); fingerstick tests were also reduced (-6.2 [*P < 0.001] and -6.9 [*P < 0.001]). Similar outcomes were observed from U.S. RWD. Conclusions: MiniMed™ 780G with G4S use was associated with significant reduction in diabetes management burden with fewer closed-loop exits, fingersticks and other interactions, and improvements in glycemic control when compared to the MiniMed™ 670G with GS3.

Measurement of carotid plaque burden: A tool for predicting and preventing dementia?

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Strokes markedly increase the risk of dementia from Alzheimer disease, and preventing strokes reduces the risk of dementia. Delaying dementia by 5 years nearly halves the incidence of dementia, because old patients often die before dementia is expressed.

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Carotid plaque burden is a strong predictor of the risk of stroke, and measurement of plaque burden has also been used to treat atherosclerosis. In high-risk patients with asymptomatic carotid stenosis, doing so was associated with a >80% reduction of the 2-year risk of stroke and myocardial infarction compared to usual therapy.

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We found that high plaque burden was significantly associated with impairment of cognitive function.

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We suggest that measurement of carotid plaque burden may be a powerful tool not only for predicting risk of dementia, but also for preventing dementia.

Introduction

Carotid plaque burden is a strong predictor of stroke risk, and preventing stroke reduces the risk of dementia. Treating carotid plaque burden markedly reduces the risk of stroke.

Methods

Among patients age 65–80 years attending a stroke prevention clinic, we identified those with a carotid plaque burden in the top 20% of Total Plaque Area (High TPA) and the bottom 20% (Low TPA) and performed cognitive tests: The Montreal Cognitive Assessment test (MoCA), the WAIS-III Digit Symbol-Coding Test (DSST) and Trail-Making Test (TMT) part A and B.

Results

There were 31 patients recruited; 11 Low TPA (5 men) and 20 High TPA (17 men), p = 0.04. TPA was 35 ± 25 mm² in the Low TPA vs.392 ± 169 mm² in the High TPA group (0.0001). Patients with a high plaque burden had significantly worse performance on all the cognitive tests, all p< 0.05

Discussion

A high carotid plaque burden identifies patients at risk of cognitive impairment. Because carotid plaque burden is treatable, and treating it markedly reduces the risk of stroke, we suggest that measurement of plaque burden is a useful tool for both prediction of cognitive impairment, and prevention of dementia.

Inverse Association between Serotonin 2A Receptor Antagonist Medication Use and Mortality in Severe COVID-19 Infection

Advanced age and medical co-morbidity are strong predictors of mortality in COVID-19 infection. Yet few studies (to date) have specifically addressed risk factors associated with COVID-19 mortality in a high-risk subgroup of older US adults having one or more chronic diseases. Our hypothesis is that medications having 'off-target' anti-inflammatory effects may play a role in modulating the immune response in COVID-19 infection. We analyzed baseline risk factors associated with respiratory failure or death in 55 older adult US military veterans hospitalized for COVID-19 infection during (March-June 2020) the peak of the pandemic in New Jersey. Fifty-three percent (29/55) of patients experienced respiratory failure and thirty-one percent (17/55) died. In adjusted logistic regression analysis, baseline neutrophil to lymphocyte ratio (NLR) (P=0.0035) and body mass index (P=0.03) were significant predictors of the risk for respiratory failure. Age (P=0.05) and non-use (vs. use) of psychotropic medications having serotonin 2A receptor antagonist properties (odds ratio 5.06; 95% confidence intervals 1.18-21.7; P= 0.029) was each a significant predictor of an increased risk of death. There was a significant interaction effect of age and non-use (vs.. use) of psychotropic serotonin 2A receptor antagonist medications on the odds ratio (OR) for death (P=0.011). In selected, ventilator-dependent COVID-19 pneumonia patients treated with psychotropic serotonin 2A receptor antagonist medications to control agitation and ICU delirium, there was an apparent positive association between medication use and significant rise in the absolute lymphocyte count and decrease in the neutrophil: lymphocyte ratio. Taken together, these data are the first to suggest that certain psychotropic medications used in the treatment of chronic psychiatric illness and/or for acute delirium are inversely associated with mortality in severe COVID-19 infection by unknown mechanism which may involve (in part) immunomodulatory effects.

Endothelial Cell Growth Promoting Activity in Graves' Disease Sera is Neutralized by Anti-Basic Fibroblast Growth Factor Antibodies in Patients with Fat Expansive but Not Infiltrative Orbitopathy

PURPOSE

To report a case of orbital fat expansion leading to globe prolapse in a Graves' disease patient undergoing high-dose glucocorticoid therapy. To evaluate the growth factor receptor specificities of plasma autoantibodies in Graves' disease patients who exhibited contrasting subtypes of thyroid-associated ophthalmopathy, i.e. orbital fat expansion-type vs. infiltrative.

METHODS

Sera from Graves' orbitopathy and control patients with or without Graves' disease were subjected to protein-A affinity chromatography to obtain immunoglobulin G. A (1/50th to 1/1600th) range in dilutions of the protein-A eluate fraction was incubated for four days at 37 degrees C with bovine pulmonary artery endothelial cells to test for endothelial cell inhibition or stimulation. Growth stimulatory autoantibodies were co-incubated with specific neutralizing anti-insulin like growth factor 1 receptor antibodies or anti-basic fibroblast growth factor antibodies to assess autoantibody specificity in contrasting Graves' orbitopathy subtypes.

RESULTS

We observed increased mean endothelial cell growth promoting activity in the protein-A eluates of serum from eighteen patients with active Graves' disease (117 ± 28%, n = 18) compared to mean endothelial cell activity (89 ± 10%, n = 13, P = 0.003) in thirteen adults without Graves' disease. The protein-A eluate fraction in acute infiltrative-type Graves' orbitopathy contained a high titer (> 1:1000) of endothelial cell stimulatory activity which was significantly neutralized by specific monoclonal anti-human insulin-like growth factor 1 receptor antibodies. The protein-A eluate fraction in fat expansion-type Graves' orbitopathy contained endothelial cell inhibitory activity (at low titers) and stimulatory activity (at high titers), and the latter stimulatory activity was completely neutralized by specific anti-basic fibroblast growth factor antibodies.

CONCLUSION

Graves' disease suffering globe prolapse secondary to marked orbital fat-expansion had coexisting plasma fibroblast growth factor-inhibitory and -stimulatory autoantibodies. The latter was completely neutralized by anti-basic fibroblast growth factor antibodies.

Systematic identification of genes involved in metabolic acid stress resistance in yeast and their potential as cancer targets

A hallmark of all primary and metastatic tumours is their high rate of glucose uptake and glycolysis. A consequence of the glycolytic phenotype is the accumulation of metabolic acid; hence, tumour cells experience considerable intracellular acid stress. To compensate, tumour cells upregulate acid pumps, which expel the metabolic acid into the surrounding tumour environment, resulting in alkalization of intracellular pH and acidification of the tumour microenvironment. Nevertheless, we have only a limited understanding of the consequences of altered intracellular pH on cell physiology, or of the genes and pathways that respond to metabolic acid stress. We have used yeast as a genetic model for metabolic acid stress with the rationale that the metabolic changes that occur in cancer that lead to intracellular acid stress are likely fundamental. Using a quantitative systems biology approach we identified 129 genes required for optimal growth under conditions of metabolic acid stress. We identified six highly conserved protein complexes with functions related to oxidative phosphorylation (mitochondrial respiratory chain complex III and IV), mitochondrial tRNA biosynthesis [glutamyl-tRNA(Gln) amidotransferase complex], histone methylation (Set1C-COMPASS), lysosome biogenesis (AP-3 adapter complex), and mRNA processing and P-body formation (PAN complex). We tested roles for two of these, AP-3 adapter complex and PAN deadenylase complex, in resistance to acid stress using a myeloid leukaemia-derived human cell line that we determined to be acid stress resistant. Loss of either complex inhibited growth of Hap1 cells at neutral pH and caused sensitivity to acid stress, indicating that AP-3 and PAN complexes are promising new targets in the treatment of cancer. Additionally, our data suggests that tumours may be genetically sensitized to acid stress and hence susceptible to acid stress-directed therapies, as many tumours accumulate mutations in mitochondrial respiratory chain complexes required for their proliferation.

Hypoglycemia Prevention and User Acceptance of an Insulin Pump System with Predictive Low Glucose Management

BACKGROUND

The MiniMed 640G sensor-augmented insulin pump system (Medtronic, Inc., Northridge, CA) can automatically suspend insulin delivery in advance of predicted hypoglycemia and restart it upon recovery. The aims of this analysis were to determine the rate at which predicted hypoglycemia was avoided with this strategy, as well as to assess user acceptance of the system and its insulin management features.

SUBJECTS AND METHODS

Forty subjects with type 1 diabetes used the system for 4 weeks. We retrospectively evaluated performance of the system, using downloaded pump and sensor data, and evaluated user acceptance via questionnaires.

RESULTS

There were 2,322 suspend before low events (2.1 per subject-day). The mean (± SD) duration of pump suspension events was 56.4 ± 9.6 min, and the mean subsequent sensor glucose (SG) nadir was 71.8 ± 5.2 mg/dL. SG values following 1,930 (83.1%) of the predictive suspensions did not reach the preset low limit. Nadir SG values of ≤50 and ≤60 mg/dL were seen in 207 (8.9%) and 356 (15.3%) of the predictive suspensions, respectively. Blood glucose (BG) and SG values before and during the study were comparable (P > 0.05). The mean absolute relative difference between paired SG and BG values was 10.9 ± 13.8%. Subjects felt confident using the system, agreed that it helped protect them from hypoglycemia, and wished to continue using it.

CONCLUSIONS

Automatic insulin pump suspension as implemented in the MiniMed 640G system can help patients avoid hypoglycemia, without significantly increasing hyperglycemia.

Hypoglycemia Reduction and Changes in Hemoglobin A1c in the ASPIRE In-Home Study

BACKGROUND

ASPIRE In-Home randomized 247 subjects with type 1 diabetes to sensor-augmented pump therapy with or without the Threshold Suspend (TS) feature, which interrupts insulin delivery at a preset sensor glucose value. We studied the effects of TS on nocturnal hypoglycemia (NH) in relation to baseline hemoglobin A1c (A1C) and change in A1C during the study.

MATERIALS AND METHODS

NH event rates and mean area under curve (AUC) of NH events were evaluated at different levels of baseline A1C (<7%, 7-8%, and >8%) and at different levels of changes in A1C (less than -0.3% [decreased], -0.3% to 0.3% [stable], and >0.3% [increased]), in the TS Group compared with the Control Group (sensor-augmented pump only).

RESULTS

In the TS Group, 27.9% of the NH events were accompanied by a confirmatory blood glucose value, compared with 39.3% in the Control Group. Among subjects with baseline A1C levels of <7% or 7-8%, those in the TS Group had significantly lower NH event rates than those in the Control Group (P=0.001 and P=0.004, respectively). Among subjects with decreased or stable A1C levels, those in the TS Group had significantly lower NH event rates, and the events had lower AUCs (P≤0.001 for each). Among subjects with increased A1C levels, those in the TS Group had NH events with significantly lower AUCs (P<0.001).

CONCLUSIONS

Use of the TS feature was associated with decreases in the rate and severity (as measured by AUC) of NH events in many subjects, including those with low baseline A1C levels and those whose A1C values decreased during the study period. Use of the TS feature can help protect against hypoglycemia in those wishing to intensify diabetes management to achieve target glucose levels.

The effects of lowering nighttime and breakfast glucose levels with sensor-augmented pump therapy on hemoglobin A1c levels in type 1 diabetes

OBJECTIVE

This study determined the association of continuous glucose monitoring glucose (CGM-glucose) levels at different times of the day with improvement in glycated hemoglobin (HbA1c) levels. The potential application of these data is to focus effort to improve glucose control in patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Data were analyzed from 196 patients with type 1 diabetes who were randomized to receive sensor-augmented pump therapy in the 1-year STAR 3 trial. CGM-glucose values and HbA1c levels from baseline and after 1 year were evaluated to determine associations of improvement in CGM-glucose at different times of the day with longitudinal improvement in HbA1c.

RESULTS

Improvement in HbA1c levels after 1 year was related to improvement in mean CGM-glucose levels in daytime (6 a.m.-midnight), overnight (midnight-6 a.m.), and each mealtime period (P<0.0001 for each). In multivariable analysis, only improvement in breakfast meal period was associated with improvement in HbA1c after 1 year, explaining 59% of the HbA1c improvement using the partial R(2) test. Moreover, among those patients who only improved CGM-glucose in the overnight period there was an associated improvement in breakfast meal period CGM-glucose of 26 ± 22 mg/dL (P<0.01).

CONCLUSIONS

Breakfast period glucose improvement had the greatest effect on lowering HbA1c levels in patients with type 1 diabetes. Improving glucose control overnight resulted in subsequent improvement in the breakfast period. Although glucose control should be improved at all times, methods to improve overnight and post-breakfast glucose levels may be of primary importance in improving glucose control in patients with type 1 diabetes.

Asian Americans have greater prevalence of metabolic syndrome despite lower body mass index

Objective

To examine the relationship between body mass index and metabolic syndrome for Asian Americans and non-Hispanic Whites, given that evidence shows racial/ethnic heterogeneity exists in how body mass index predicts metabolic syndrome.

Research Design and Methods

Electronic health records of 43 507 primary care patients aged 35 years and older with self-identified race/ethnicity of interest (Asian Indian, Chinese, Filipino, Japanese, Korean, Vietnamese, or non-Hispanic White) were analyzed in a mixed-payer, outpatient-focused healthcare organization in the San Francisco Bay Area.

Results

Metabolic syndrome prevalence is significantly higher in Asians compared to non-Hispanic Whites for every body mass index category. For women at the mean age of 55 and body mass index of 25 kg/m², the predicted prevalence of metabolic syndrome is 12% for non-Hispanic White women compared to 30% for Asians; similarly for men, the predicted prevalence of metabolic syndrome is 22% for non-Hispanic Whites compared to 43% of Asians. Compared to non-Hispanic White women and men with a body mass index of 25 kg/m², comparable prevalence of metabolic syndrome was seen at body mass index of 19.6 kg/m² for Asian women and 19.9 kg/m² for Asian men. A similar pattern was seen in disaggregated Asian subgroups.

Conclusions

Despite lower body mass index values and lower prevalence of overweight/obesity than non-Hispanic Whites, Asian Americans have higher rates of metabolic syndrome over the range of body mass index. Our results indicate that body mass index ranges for defining overweight/obesity in Asian populations should be lower than for non-Hispanic Whites.

Detection of disease recurrence in differentiated thyroid cancer

Thyroid cancer is the most common malignancy of the endocrine system, with an incidence that has been increasing for several decades. Differentiated thyroid carcinomas, which account for more than 90% of thyroid cancers, are generally indolent tumors with excellent long-term prognosis. However, the recurrence rates of differentiated thyroid cancers are high. In recognition of the growing incidence of thyroid cancer and its unfavorable risk of recurrence, several management guidelines have been established in order to effectively diagnose and treat initial and recurrent diseases at an early stage. Furthermore, the guidelines acknowledge the improvements in diagnostic modalities that have brought about a major paradigm shift in the management of thyroid cancer and surveillance for recurrence. This review will discuss the most current and advanced strategies for detection of recurrent differentiated thyroid cancer.

Validation of a novel risk estimation tool for predicting low bone density in Caucasian and African American men veterans

Osteoporosis in men is a frequently missed diagnosis. We developed an additive risk index, Mscore (male, "simple calculated osteoporosis risk estimation"), based on bone mineral density (BMD) at the femoral neck (FN) in 639 ambulatory older male veterans. Mscore was derived from the nearest whole number ratio among regression coefficients for 5 variables independently associated with osteoporosis. Mscore=[2 x (patient age in decades)-(weight in lb/10)+4 if gastrectomy, +4 if emphysema, +3 if two or more prior fractures+14]. Age and weight variable scores are truncated to integers (i.e., 7 if 75 yr, 18 if 185 lb). Increased risk is reflected in higher Mscore values. We validated Mscore in 197 Caucasian male patients (mean age, 69 yr): values of 9 or higher had 88% sensitivity, 57% specificity, and an area under the curve (AUC) of 0.84 for predicting osteoporosis at the FN (population prevalence, 11%). Mscore values ranged from -9 to 20 allowing us to define low (<9), moderate (9-13), or high (>13) risk categories. Two percent of low-risk men had osteoporosis, 36% or 55% of high-risk men had osteoporosis or osteopenia, respectively. In younger African American (n=134) male veterans (mean age, 61 yr), age and weight were the only variables independently predictive of FN BMD. A reduced Mscore(age-weight) (age and weight variable scores+14) at a cutoff threshold of 9 predicted osteoporosis in African American men (population prevalence, 3%) with a sensitivity of 100%, a specificity of 73%, and an AUC of 0.99. Finally, we compared Mscore with another validated osteoporosis self-assessment tool (OST). OST at a cutoff threshold of 4 or Mscore(age-weight) at a cutoff threshold of 9 performed similarly in both of our populations of Caucasian and African American men. In conclusion, a validated Mscore index with 5 variables was only slightly more robust for predicting osteoporosis in older Caucasian men than 2 (independently derived) risk indices based on age and weight. Mscore(age-weight) or OST is easy to use and can be applied in populations of younger African American men.

Differential effect of obesity on bone mineral density in White, Hispanic and African American women: a cross sectional study

Osteoporosis is a major public health problem with low bone mass affecting nearly half the women aged 50 years or older. Evidence from various studies has shown that higher body mass index (BMI) is a protective factor for bone mineral density (BMD). Most of the evidence, however, is from studies with Caucasian women and it is unclear to what extent ethnicity plays a role in modifying the effect of BMI on BMD.

A cross sectional study was performed in which records of postmenopausal women who presented for screening for osteoporosis at 2 urban medical centres were reviewed. Using logistic regression, we examined the interaction of race and BMI after adjusting for age, family history of osteoporosis, maternal fracture, smoking, and sedentary lifestyle on BMD. Low BMD was defined as T-score at the lumbar spine < -1.

Among 3,206 patients identified, the mean age of the study population was 58.3 ± 0.24 (Years ± SEM) and the BMI was 30.6 kg/m². 2,417 (75.4%) were African Americans (AA), 441(13.6%) were Whites and 348 (10.9%) were Hispanics. The AA women had lower odds of having low BMD compared to Whites [Odds ratio (OR) = 0.079 (0.03–0.24) (95% CI), p < 0.01]. The odds ratio of low BMD was not statistically significant between White and Hispanic women. We examined the interaction between race and BMD. For White women; as the BMI increases by unity, the odds of low BMD decreases [OR = 0.9 (0.87–0.94), p < 0.01; for every unit increase in BMI]. AA women had slightly but significantly higher odds of low BMD compared to Whites [OR 1.015 (1.007–1.14), p <0.01 for every unit increase in BMI]. This effect was not observed when Hispanic women were compared to Whites.

There is thus a race-dependent effect of BMI on BMD. With each unit increase in BMI, BMD increases for White women, while a slight but significant decrease in BMD occurs in African American women.

Control of blood pressure and other cardiovascular risk factors at different practice settings: outcomes of care provided to diabetic women compared to men

Cardiovascular disease (CVD) is the major cause of morbidity and mortality in diabetes. To determine the proportion of patients who met the American Diabetes Association guidelines for control of CVD risk factors and to assess the achievement of these guidelines in women compared with men, we conducted a cross-sectional study of 3678 diabetic cohorts followed at seven medical centers, two Veteran Administration hospitals, three urban clinics, and two suburban clinics. Overall, 28% met the target blood pressure of <130/80 mm Hg, 48.8% achieved a goal low-density lipoprotein cholesterol of <100 mg/dL, and 35.8% had hemoglobin A1c of <7%. Gender comparisons of 2788 diabetic patients at urban and suburban centers showed that women had a lower percentage of low-density lipoprotein cholesterol <100 mg/dL (45.8 vs. 51.3, p<0.01) and a lower percentage of screening for retinopathy (54 vs. 60, p<0.01) and nephropathy (37 vs. 49, p<0.01). However, overall there were no gender differences in the percentage of patients who achieved a goal blood pressure <130/80 mm Hg or hemoglobin A1c <7%. Control of blood pressure and other CVD risk factors in diabetic patients was largely suboptimal, especially for diabetic women. These observations underscore the need for better strategies for control of CVD risk in the diabetic population in general, and women in particular.

Association of diabetes and hepatitis C infection: epidemiologic evidence and pathophysiologic insights

Up to one third of patients with chronic hepatitis C virus (HCV) develop type 2 diabetes mellitus (DM). This prevalence is much higher than that observed in the general population, and in patients with other chronic liver diseases such as hepatitis B virus, alcoholic liver disease, and primary biliary cirrhosis. Further, HCV seropositivity in patients with DM appears to be higher than in the general population. Post- liver transplantation DM also appears to be higher among patients with HCV. In this article, we review the epidemiologic association between HCV and DM, highlighting the most recent pathophysiologic insights into the mechanisms underlying this association.

Osteoporosis and cardiovascular disease: brittle bones and boned arteries, is there a link?

Both osteoporosis and cardiovascular disease (CVD) are major public health problems leading to increased morbidity and mortality. Although traditionally viewed as separate disease entities that increase in prevalence with aging, accumulating evidence indicates that there are similar pathophysiological mechanisms underlying both diseases. In addition to menopause and advanced age, other risk factors for CVD such as dyslipidemia, oxidative stress, inflammation, hyperhomocystinemia, hypertension, and diabetes have also been associated with increased risk of low bone mineral density (LBMD). Elevated LDL and low HDL cholesterol are associated with LBMD, altered lipid metabolism is associated with both bone remodeling and the atherosclerotic process, which might explain, in part, the co-existence of osteoporosis and atherosclerosis in patients with dyslipidemia. Similarly, inflammation plays a pivotal role in both atherosclerosis and osteoporosis. Elevated plasma homocysteine levels are associated with both CVD and osteoporosis. Nitric oxide (NO), in addition to its known atheroprotective effects, appears to also play a role in osteoblast function and bone turnover. Supporting this notion, in a small randomized controlled trial, nitroglycerine (an NO donor) was found to be as effective as estrogen in preventing bone loss in women with surgical menopause. Statins, agents that reduce atherogenesis, also stimulate bone formation. Furthermore, bis- phosphonates, used in the treatment of osteoporosis, have been shown to inhibit atherogenesis. Intravenous bisphosphonate therapy significantly decreases serum LDL and increases HDL in postmenopausal women The exciting possibilities of newer pharmacological agents that effectively treat both osteoporosis and CVD hold considerable promise. However, it is important to emphasize that the current evidence linking both of these diseases is far from conclusive. Therefore, additional research is necessary to further characterize the relationship between these two common illnesses.

Role of oral anti-diabetic agents in modifying cardiovascular risk factors

Patients with type 2 diabetes have an increased risk for cardiovascular disease (CVD) and it accounts for up to 80% of excess deaths in these patients. It has been recognized that type 2 diabetes is associated with an increased prevalence of CVD risk factors, including hypertension, dyslipidemia, microalbuminuria, and altered hemostasis. The benefit of cardiovascular protection can only be partially explained by controlling hyperglycemia. Some of the oral agents used to treat hyperglycemia significantly modify other cardiovascular risk factors. This article will review oral agents used to treat type 2 diabetes and their effects on modifying CVD risk factors.

CT guided pararectal seed implant for localized prostate cancer: a preliminary report

One hundred and fifty-two patients were treated with CT guided pararectal prostate seed implant (CPSI) alone or in combination with external-beam 3D conformal radiation therapy (EB3DRT) and Androgen Blockage Hormone Therapy (HT). A decrease and normalization in PSA values was seen following treatment in all groups. However, a better therapeutic response was observed in the individuals that received CPSI and EB3DRT with hormone therapy.

Prevention of type 2 diabetes

Diabetes is a major public health problem that is approaching epidemic proportions in our society and worldwide. Cardiovascular disease is the major cause of morbidity and mortality in people with diabetes. Control of cardiovascular disease risk factors is achieved only in a minority of patients. Given the magnitude of the problem and the seriousness of diabetes complications, prevention appears to be a logical approach to curb the rising prevalence of the disease. Interventions such as lifestyle modifications and the use of metformin and acarbose have been shown in randomized prospective trials to prevent diabetes in high-risk patients. Other interventions are currently being examined in large prospective studies. It is likely that one or a combination of these approaches will make diabetes prevention a reality in the near future.

Identification of 4-coumarate:coenzyme A ligase (4CL) substrate recognition domains

4-coumarate:CoA ligase (4CL), the last enzyme of the general phenylpropanoid pathway, provides precursors for the biosynthesis of a large variety of plant natural products. 4 CL catalyzes the formation of CoA thiol esters of 4-coumarate and other hydroxycinnamates in a two step reaction involving the formation of an adenylate intermediate. 4 CL shares conserved peptide motifs with diverse adenylate-forming enzymes such as firefly luciferases, non-ribosomal peptide synthetases, and acyl:CoA synthetases. Amino acid residues involved in 4 CL catalytic activities have been identified, but domains involved in determining substrate specificity remain unknown. To address this question, we took advantage of the difference in substrate usage between the Arabidopsis thaliana 4 CL isoforms At4CL1 and At4CL2. While both enzymes convert 4-coumarate, only At4CL1 is also capable of converting ferulate. Employing a domain swapping approach, we identified two adjacent domains involved in substrate recognition. Both substrate binding domain I (sbd I) and sbd II of At4CL1 alone were sufficient to confer ferulate utilization ability upon chimeric proteins otherwise consisting of At4CL2 sequences. In contrast, sbd I and sbd II of At4CL2 together were required to abolish ferulate utilization in the context of At4CL1. Sbd I corresponds to a region previously identified as the substrate binding domain of the adenylation subunit of bacterial peptide synthetases, while sbd II centers on a conserved domain of so far unknown function in adenylate-forming enzymes (GEI/LxIxG). At4CL1 and At4CL2 differ in nine amino acids within sbd I and four within sbd II, suggesting that these play roles in substrate recognition.

Transplanted neuroblasts differentiate appropriately into projection neurons with correct neurotransmitter and receptor phenotype in neocortex undergoing targeted projection neuron degeneration

Reconstruction of complex neocortical and other CNS circuitry may be possible via transplantation of appropriate neural precursors, guided by cellular and molecular controls. Although cellular repopulation and complex circuitry repair may make possible new avenues of treatment for degenerative, developmental, or acquired CNS diseases, functional integration may depend critically on specificity of neuronal synaptic integration and appropriate neurotransmitter/receptor phenotype. The current study investigated neurotransmitter and receptor phenotypes of newly incorporated neurons after transplantation in regions of targeted neuronal degeneration of cortical callosal projection neurons (CPNs). Donor neuroblasts were compared to the population of normal endogenous CPNs in their expression of appropriate neurotransmitters (glutamate, aspartate, and GABA) and receptors (kainate-R, AMPA-R, NMDA-R. and GABA-R), and the time course over which this phenotype developed after transplantation. Transplanted immature neuroblasts from embryonic day 17 (E17) primary somatosensory (S1) cortex migrated to cortical layers undergoing degeneration, differentiated to a mature CPN phenotype, and received synaptic input from other neurons. In addition, 23.1 +/- 13.6% of the donor-derived neurons extended appropriate long-distance callosal projections to the contralateral S1 cortex. The percentage of donor-derived neurons expressing appropriate neurotransmitters and receptors showed a steady increase with time, reaching numbers equivalent to adult endogenous CPNs by 4-16 weeks after transplantation. These results suggest that previously demonstrated changes in gene expression induced by synchronous apoptotic degeneration of adult CPNs create a cellular and molecular environment that is both permissive and instructive for the specific and appropriate maturation of transplanted neuroblasts. These experiments demonstrate, for the first time, that newly repopulating neurons can undergo directed differentiation with high fidelity of their neurotransmitter and receptor phenotype, toward reconstruction of complex CNS circuitry.

Fuzzy assessment of sleep-disordered breathing during continuous positive airway pressure therapy

We propose a new method of quantifying sleep-disordered breathing (SDB) for the purpose of automating continuous positive airway pressure (CPAP) titration. Our algorithm, based on fuzzy logic, emulates the less-than-crisp kind of decision-making generally employed at the human level. Three input variables were first derived on a breath-by-breath basis from respiratory airflow measurements. These were: (1) the relative duration of inspiratory flow limitation in each breath; (2) the degree of hypopnea relative to the past 15 breaths; and (3) the intensity of snoring. Using these descriptors as inputs, our fuzzy inference algorithm produced a "severity index" (SI) quantifying the degree of SDB. Severity index was determined in CPAP titration procedures conducted on one normal snorer and 12 patients with moderate-to-severe obstructive sleep apnea. SI computed over the last 6 minutes of each CPAP level was compared against other more-conventional indices of SDB, such as total pulmonary resistance (RL), the number of apneas and hypopneas (NAH), and the number of arousals (NAr). In all but one of the subjects, the correlation coefficients for SI vs each of RL, NAH, and NAr were significantly different from zero, but not different from each other. The group correlation coefficients for SI vs RL, NAH, and NAr were 0.89, 0.86, and 0.87, respectively, demonstrating that SI accurately quantifies SDB. SI collapses multiple features of the airflow pattern into a single index and, therefore, may be useful as a "feedback" variable for the automatic control of CPAP therapy.

Requirement for Brn-3c in maturation and survival, but not in fate determination of inner ear hair cells

Mutations in the POU domain gene Brn-3c causes hearing impairment in both the human and mouse as a result of inner ear hair cell loss. We show here that during murine embryogenesis, Brn-3c is expressed in postmitotic cells committed to hair cell phenotype but not in mitotic progenitors in the inner ear sensory epithelium. In developing auditory and vestibular sensory epithelia of Brn-3c−/− mice, hair cells are found to be generated and undergo initial differentiation as indicated by their morphology, laminar position and expression of hair cell markers, including myosins VI and VIIa, calretinin and parvalbumin. However, a small number of hair cells are anomalously retained in the supporting cell layer in the vestibular sensory epithelia. Furthermore, the initially differentiated hair cells fail to form stereociliary bundles and degenerate by apoptosis in the Brn-3c−/− mice. These data indicate a crucial role for Brn-3c in maturation, survival and migration of hair cells, but not in proliferation or commitment of hair cell progenitors.

Ventilatory dynamics of transient arousal in patients with obstructive sleep apnea

The hyperpnea that accompanies arousal at the end of obstructive apnea is believed to be due to the progressive build-up in chemical drive during the apnea and a state-related decrease in upper airway resistance. We postulated the existence of a third component: a state-related transient increase in neural drive to the ventilatory pump muscles. To quantify this contribution, we measured the ventilatory response to arousal (VRA) in eight patients with obstructive sleep apnea (OSA) during continuous positive airway pressure (CPAP) therapy, applied at individually titrated levels. CPAP application reduced total pulmonary resistance (RL) to approximately normal levels, stabilizing ventilation and sleep state. Transient arousal from stage 2 sleep was induced using 5-sec tones (60-90 dB). Mean inspiratory flow increased above control on the second and third post-arousal breaths (P < 0.05), with a peak increase of 7.8 +/- 2.9 L/min while the accompanying changes in RL were significant. The time-course of VRA measured in three normal subjects under CPAP was similar to that observed in the OSA patients. However, elimination of CPAP prolonged the VRA time-course. Taken together, these findings demonstrate that: (1) during arousal, the increase in state-related neural respiratory drive is short-lived but not substantial; and (2) the resulting VRA time-course is shaped by the dynamics of the upper airway response to arousal.

Novel genes expressed in the chick otocyst during development: identification using differential display of RNA

Differential display of mRNA is a technique that enables the researcher to compare genes expressed in two or more different tissues or in the same tissue or cell under different conditions. The method is based on polymerase chain reaction amplification and comparison of specific subsets of mRNA. We have used this method to clone partial complementary DNAs (cDNAs; amplicons) for genes expressed in the otocyst in order to identify genes that may be involved in development of the inner ear. A full length cDNA was isolated from an embryonic quail head library with an amplicon (KH121) obtained from the otocyst. This avian cDNA encoded a novel, 172-amino acid acidic protein and detected a major transcript of ca 0.8 kb in RNA from chick embryos and several neonatal chick tissues. The full length avian cDNA had high sequence identity to several human cDNAs (expressed sequence tags) from human fetal tissues, including cochlea, brain, liver/spleen and lung, and from placenta. The human homologue of the avian gene encoded a protein that was 183 amino acids long and had 75.6% amino acid sequence identity to the avian protein. These results identified both the avian and human homologues of an evolutionarily conserved gene encoding a small acidic protein of unknown function; however, expression of this gene was not restricted to otocysts.

Complete cDNAs for CDC42 from chicken cochlea and mouse liver

CDC42 is a member of the ras superfamily of small GTP-binding proteins that are related through the highly conserved GTP-binding domain and are involved in signal transduction pathways. Two full-length CDC42 cDNAs have been isolated: a 2148-bp chick cochlea cDNA and a 2063-bp mouse liver cDNA. Each encodes a CDC42 protein of 191 amino acids. The avian CDC42 protein differs from the mouse at only one amino acid residue, a Thr for a Ser at position 185. Both CDC42 proteins are more similar to the ubiquitous human isoform originally isolated from placenta than to the isoform isolated from fetal brain. Using a probe from the 3' UTR of the mouse liver CDC42 cDNA, we demonstrated that the mouse gene is expressed in all tissues examined. Southern blot analysis of a mouse inter-specific backcross with this gene-specific probe identified at least three CDC42-like (Cdc42l) genes in the mouse genome. Cdc42l1 was mapped to distal mouse Chromosome 4, near Cappb1. Cdc42l2 mapped more proximal on Chromosome 4, whereas Cdc42l3 mapped to the X Chromosome.

Identification of genes expressed after noise exposure in the chick basilar papilla

We used differential display of mRNA, a method based on reverse transcriptase-PCR, to identify genes whose expression increases in response to acoustic trauma in the chick basilar papilla. Identifying these genes would provide insight into processes involved in repair of the damaged epithelium or in hair cell regeneration. We compared mRNA from the basilar papilla of normal chicks, from chicks exposed to an octave band noise (center frequency: 1.5 kHz) presented at 118 dB for 6 h, and from chicks exposed to noise and allowed to recover for 2 days. Thus far, we have identified 70 bands that appear to be differentially displayed on DNA sequencing gels; approximately 40 of these bands have been subcloned and sequenced. DNA sequences were compared with sequences in the GenBank database to identify genes with significant (70-85%) sequence identity to known genes. Chick cDNAs identified included: the parathyroid hormone-related protein, an immediate early gene; the delta-subunit of the neuronal-specific Ca2+/calmodulin-regulated protein kinase II; and the GTP-binding protein CDC42, a member of the ras superfamily of G proteins. A fourth cDNA had 84% sequence identity to an uncharacterized human cDNA (expressed sequence tag), indicating that this is a novel gene. Slot-blot hybridization analysis of these cDNAs probed with labeled DNA generated from mRNA from each experimental group indicated higher levels of mRNA for each of these four genes after noise exposure. These results indicate the potential involvement of both Ca2+/calmodulin-mediated signaling and GTPase cascades in the response to noise damage and during hair cell regeneration in the chick basilar papilla.

Ventilatory dynamics during transient arousal from NREM sleep: implications for respiratory control stability

The polysomnographic and ventilatory patterns of nine normal adults were measured during non-rapid-eye-movement (NREM) stage 2 sleep before and after repeated administrations of a tone (40-72 dB) lasting 5 s. The ventilatory response to arousal (VRA) was determined in data sections showing electrocortical arousal following the start of the tone. Mean inspiratory flow and tidal volume increased significantly above control levels in the first seven breaths after the start of arousal, with peak increases (64.2% > control) occurring on the second breath. Breath-to-breath occlusion pressure 100 ms after the start of inspiration showed significant increases only on the second and third postarousal breaths, whereas upper airway resistance declined immediately and remained below control for > or = 7 consecutive breaths. These results suggest that the first breath and latter portion of the VRA are determined more by upper airway dynamics than by changes in the neural drive to breathe. Computer model simulations comparing different VRA time courses show that sustained periodic apnea is more likely to occur when the fall in the postarousal increase in ventilation is more abrupt.

Estimation of dynamic chemoresponsiveness in wakefulness and non-rapid-eye-movement sleep

We developed a method for quantifying dynamic chemoresponsiveness on the basis of the ventilatory response to pseudorandom binary CO2 stimulation. The dynamic chemoreflex gain (GD) and effective time delay (TDeff) relating breath-to-breath fluctuations in alveolar PCO2 to ventilation were evaluated at frequencies between 0 and 0.05 Hz. Application of the method to simulated "data" showed that estimation errors in GD and TDeff were most likely to be minimized in the range of 0.01-0.03 Hz, corresponding to periodicities of 30-100 s. Estimation of TDeff was generally more susceptible to error than that of GD because of the limited time resolution of the breath-by-breath measurements. In eight awake normal adults, we compared estimates of GD derived from the pseudorandom binary CO2 stimulation test with peripheral and central hypercapnic sensitivities deduced from single-breath and Read rebreathing measurements in the same subject. GD at 0.02 Hz was highly correlated with peripheral hypercapnic sensitivity but poorly correlated with central hypercapnic sensitivity, underscoring the importance of the peripheral chemoreflexes in mediating ventilatory responses to phasic stimuli. Application of the procedure to a different group of 10 healthy volunteers during wakefulness and stage 2 sleep showed decreases in GD in 8 subjects but increases in 2 subjects. However, for the group as a whole, GD and TDeff did not change significantly between wakefulness and sleep. The proposed method may provide information more pertinent to periodic breathing than traditional CO2 response tests do, since the chemoreflex responses to phasic variations in blood gases are likely to be important in determining ventilatory control during sleep.