Citations

OBJECTIVE To evaluate both the concordance in the classification of diabetes by clinical and C-peptide criteria and, prospectively, the consistency of the classification by C-peptide. RESEARCH DESIGN AND METHODS Individuals with diabetes who were enlisted in the prospective epidemiological study of diabetic neuropathy (Rochester Diabetic Neuropathy Study [RDNS]) were classified clinically by National Diabetes Data Group (NDDG) criteria to IDDM and NIDDM at entry to the study. In addition, C-peptide response to 1 mg glucagon was measured at entry for the classification to IDDM (basal C-peptide, < 0.17 pmol/ml; increment above basal, < 0.07 pmol/ml) and NIDDM (all other responses) and for concordance with the clinical classification made. The consistency of the C-peptide response was assessed every 2 years for up to 8 years. RESULTS Among 346 individuals with diabetes, 84 were classified as IDDM and 262 as NIDDM by clinical algorithm. COncordance with the C-peptide response occurred in 89% of the patients and remained consistent during 8 years of follow-up. Among the 37 patients with discordant clinical and C-peptide classification, those considered clinically to have NIDDM had a consistent IDDM C-peptide response during follow-up, and most of those considered to have IDDM clinically eventually showed an IDDM C-peptide response during follow-up. CONCLUSIONS Clinical criteria for the classification of diabetes are highly correlated with the assessment of insulin secretory reserve. A small number of individuals considered to have NIDDM clinically or by C-peptide have or develop an IDDM peptide response.

Use of nerve conduction in assessing therapy in preventing or ameliorating neuropathy is desirable because abnormalities of nerve conduction are associated with severity of neuropathic symptoms and deficits. Assuming that a therapy is associated with a statistically significant improvement of nerve conduction, what degree of nerve conduction change is clinically meaningful? We suggest that in controlled clinical trials, a mean change of 2 points on the neurologic disability score is clinically detectable and meaningful. Based on our previously published crosssectional epidemiological data, this corresponds to a change of motor nerve conduction velocity of the average ulnar median and peroneal nerves of 2.9 m/s and peroneal nerve of 2.2 m/s. The corresponding changes of amplitude were 1.2 and 0.7 mV, respectively. Smaller degrees of nerve conduction change were found when only insulin-dependent patients were evaluated.

Increasingly more tests are being used to detect and characterize diabetic polyneuropathy, but their value in setting minimal criteria for the diagnosis of neuropathy and for staging severity remains inadequately studied. In 180 diabetics, we compared the percentage of patients with test abnormalities and associations among test results, evaluating neuropathic symptoms [neuropathy symptom score (NSS) and neuropathy scale of neuropathy symptom profile (NNSP)], deficits [neurologic disability score (NDS) and vibratory (VDT) and cooling (CDT) detection thresholds], or nerve dysfunction [nerve conduction (NC)]. The percentage of patients that were abnormal varied considerably depending on criteria for abnormality and the tests used. Abnormality (≥ 3 SD of 1 or more parameters) of NC of one or more of four nerves occurred in 80%, of two or more in 69%, of three or more in 46%, and of four in 21%. Similarly, for other tests, the rate of abnormality decreased with use of increasingly stringent criteria. Setting the criteria for abnormal NC at abnormality of two or more nerves, NSS at ≥ 1, NDS at > 6, NNSP at ≥ 97.5th percentile, and at ≥ 95th percentile for the other tests, NC was abnormal in 69%, NSS in 54%, NDS in 48%, NNSP in 47%, VDT in 44%, and CDT in 35%. Abnormality of any two or more of the six tests evaluated occurred in 64% of patients. We estimated that at least 16% of patients without abnormal NC (<2 abnormal nerves) had other findings indicative of neuropathy. By regression analysis, results of one test were in almost all cases associated with those of another test, but the association was not close enough to be predictive. Therefore, although NC provides objective and repeatable results, symptoms and deficits must be measured independently. Assuming no differences between groups of patients, the standardized and validated test (NNSP, VDT, or CDT) should provide the same results at different medical centers. By contrast, the results of NSS or NDS tests, with less standardized approaches and based on the judgment of physicians, might not provide the same results at different medical centers. Tests such as the ones described here may be used to define minimal criteria for the diagnosis of polyneuropathy and for staging its severity.

OBJECTIVE— Because α-lipoic acid (ALA), a potent antioxidant, prevents or improves nerve conduction attributes, endoneurial blood flow, and nerve (Na(+) K(+) ATPase activity in experimental diabetes and in humans and may improve positive neuropathic sensory symptoms, in this report we further assess the safety and efficacy of ALA on the Total Symptom Score (TSS), a measure of positive neuropathic sensory symptoms. RESEARCH DESIGN AND METHODS— Metabolically stable diabetic patients with symptomatic (stage 2) diabetic sensorimotor polyneuropathy (DSPN) were randomized to a parallel, double-blind study of ALA (600 mg) (n = 60) or placebo (n = 60) infused daily intravenously for 5 days/week for 14 treatments. The primary end point was change of the sum score of daily assessments of severity and duration of TSS. Secondary end points were sum scores of neuropathy signs (NIS), symptoms (NSC), attributes of nerve conduction, quantitative sensation tests (QSTs), and an autonomic test. RESULTS— At randomization, the groups were not significantly different by the criteria of metabolic control or neuropathic end points. After 14 treatments, the TSS of the ALA group had improved from baseline by an average of 5.7 points and the placebo group by an average of 1.8 points (P < 0.001). Statistically significant improvement from baseline of the ALA, as compared with the placebo group, was also found for each item of the TSS (lancinating and burning pain, asleep numbness and prickling), NIS, one attribute of nerve conduction, and global assessment of efficacy. CONCLUSIONS— Intravenous racemic ALA, a potent antioxidant, rapidly and to a significant and meaningful degree, improved such positive neuropathic sensory symptoms as pain and several other neuropathic end points. This improvement of symptoms was attributed to improved nerve pathophysiology, not to increased nerve fiber degeneration. Because of its safety profile and its effect on positive neuropathic sensory symptoms and other neuropathic end points, this drug appears to be a useful ancillary treatment for the symptoms of diabetic polyneuropathy.

The fitting of mathematical models to physiological sys tems can be tedious and difficult, whether one uses analog or digital computer methods. Both methods have their pros and cons depending on the available hardware and software and on the type of modeling. In recent years many digital simulation languages have been written com bining analog-like and digital features to facilitate model ing, but, for a variety of reasons, none of these was suit able for our applications. We, therefore, designed a new digital simulation control system, SIMCON, which is de scribed in this paper. The primary objectives were to provide: (1) Maximum man-machine interaction at run-time, in cluding visual displays, digital control, and both con tinuous analog and digital parameter adjustment (2) The ability to generate solutions and to fit them to experimental data or other theoretical curves with a minimum of computer memory (3) The option to use a mathematically oriented language, FORTRAN, and block operators with variable input/ output. The result is a relatively general and simple simulation system which is easy to use and has wide versatility.

Background and Purpose— Genetic factors influence risk for ischemic stroke and likely do so at multiple steps in the pathogenic process. Variants in genes related to inflammation contribute to risk of stroke. The purpose of this study was to confirm our earlier finding of an association between allele 2 of a variable number tandem repeat of the IL-1 receptor antagonist gene ( IL1RN ) and cerebrovascular disease. Methods— An association study of the variable number tandem repeat genotype with ischemic stroke and stroke subtypes was performed on samples from a North American study of affected sibling pairs concordant for ischemic stroke and 2 North American cohorts of prospectively ascertained ischemic stroke cases and unrelated controls. DNA analysis was performed on cases and controls, stratified by race. Results— After adjustment for age, sex, and stroke risk factors, the odds ratio for association of allele 2 and ischemic stroke was 2.80 (95% confidence interval, 1.29 to 6.11; P =0.03) for the white participants. The effect of allele 2 of IL1RN on stroke risk most closely fits a recessive genetic model ( P =0.009). For the smaller sample of nonwhite participants, the results were not significant. Conclusions— Allele 2 of IL1RN , present in nearly one-quarter of stroke patients, may contribute to genetic risk for ischemic stroke and confirm the previously identified association with cerebrovascular disease. These results are driven by the association in the white participants. Further exploration in a larger nonwhite sample is warranted.

Abstract Pregnancy-associated plasma protein A (PAPP-A), a metalloproteinase that regulates IGF bioavailability in vitro through cleavage of inhibitory IGF-binding protein-4 (IGFBP-4), has been implicated in skeletal development and injury repair responses. However, direct in vivo data are lacking. In this study, we used PAPP-A knock-out (KO) mice to determine the role of PAPP-A in fracture repair. Stabilized mid-shaft fractures were produced in femurs of 3-month-old mice. At 14 days post-fracture, complete bony bridging of the fracture callus was seen radiographically in wild-type but not in PAPP-A KO mice. Histological examination 5 to 28 days post-fracture showed reductions in the amount of intramembranous bone formation, cartilage production, endochondral ossification and remodeling in PAPP-A KO compared with wild-type mice. However, fracture healing appeared similar in both groups at 42 days post-fracture when analyzed by histology. A similar degree of healing strength in wild-type and PAPP-A KO femurs was demonstrated by mechanical testing at 28 and 42 days post-fracture. Untreated cultures of day 5 fracture calluses from wild-type mice showed robust IGFBP-4 protease activity and IGF receptor phosphorylation, whereas fracture calluses from PAPP-A KO mice had no IGFBP-4 protease activity and reduced IGF receptor phosphorylation. These data demonstrate a marked delay in fracture healing in PAPP-A KO compared with wild-type mice, and suggest that PAPP-A is necessary in the early phases of the process for expeditious fracture repair. The ability of PAPP-A to enhance local IGF action may be an important mechanism for optimizing the fracture repair response.

AbstractRecent gene-expression data have suggested that host immune genetic signatures may predict outcomes in patients with follicular lymphoma. We evaluated the hypothesis that germ line common variation in candidate immune genes is associated with survival. Cox models were used to estimate hazard ratios (HR) and corresponding 95% confidence intervals for individual SNPs after accounting for age, clinical, and other demographic factors. The median age at diagnosis of the 278 patients was 57 years, and 59 (21%) of the patients died during follow-up, with a median follow-up of 59 months (range, 27-78 months) for surviving patients. SNPs in IL8 (rs4073; HRTT = 2.14, 1.26-3.63), IL2 (rs2069762; HRGT/TT = 1.80, 1.06-3.05), IL12B (rs3212227; HRAC/CC = 1.83, 1.06-3.06), and IL1RN (rs454078; HRAA = 1.93, 1.11-3.34) were the most robust predictors of survival. A summary score of the number of deleterious genotypes from these genes was strongly associated with survival (P = .001). A risk score that combined the 4 SNPs with the clinical and demographic factors was even more strongly associated with survival (P < .001); the 5-year Kaplan-Meier survival estimates were 96% (93%-100%), 72% (62%-83%), and 58% (48%-72%) for groups at low, intermediate, and high risk, respectively. Common variation in host immune genes warrants further evaluation as a promising class of prognostic factors in follicular lymphoma.

The changes in health care reimbursement have the potential to affect the availability of quality medical physicist service in patient care. A survey was conducted by the AAPM Professional Council and the ACMP to collect cost information for special medical physics consultation, CPT4‐77370 and continuing medical physics, CPT4‐77336. The data collected from the survey was compared to current reimbursement schemes for a number of special procedures. Under varying reimbursement schemes, the costs of the medical physics services provided cannot be recaptured by the institution. It remains important for medical physicists to assess our utilization of resources and allocation to each of the services we provide and to understand the implications of policy changes at the federal and local levels. PACS number(s): 87.90.+y, 87.53.–j