Using metabolic markers to identify insulin resistance in premenopausal women with and without polycystic ovary syndrome

BACKGROUND

Insulin resistance (IR) is associated with increased risk for type 2 diabetes mellitus and cardiovascular disease. Quantifying IR is invasive and time-consuming, and thus not routinely used in clinical practice. Simple metabolic markers to predict IR exist, but have not been validated in premenopausal women or women with polycystic ovary syndrome (PCOS).

OBJECTIVE

To evaluate the ability of metabolic markers to identify premenopausal women with/without PCOS who are insulin resistant.

DESIGN/SETTING

Cross-sectional analysis.

PARTICIPANTS

One hundred and seventy-one non-diabetic premenopausal overweight/obese women without PCOS and 71 women with PCOS.

METHODS

IR was quantified by the steady-state plasma glucose during the modified insulin-suppression test. Metabolic markers (BMI, lipid/lipoprotein concentrations, and fasting glucose) were evaluated for their discriminative ability to identify IR, using area under the receiver-operating-characteristic curve (AUROC) analysis. Optimal cut-points were evaluated for predictive power.

RESULTS

In the non-PCOS group, the triglyceride/HDL cholesterol ratio (TG/HDL-C) was the best marker (AUROC 0.73). Optimal diagnostic cut-point was 1.9. In the PCOS group, the TG/HDL-C ratio, cholesterol/HDL-C ratio (TC/HDL-C), and HDL-C performed well (AUROC > 0.80), with optimal cut-points for TG/HDL-C 1.3, TC/HDL-C 3.4, and HDL-C 52 mg/dL: TG/HDL-C was more sensitive, but HDL-C had a higher PPV for IR.

CONCLUSION

TG/HDL-C can identify IR in premenopausal women with and/without PCOS; diagnostic cut-points differ from those of men and postmenopausal women. HDL-C is an alternative predictor in women with PCOS. These simple metabolic markers, which are standardized between labs, inexpensive, and routinely measured, can be used to tailor lifestyle and medical interventions to improve health outcomes in insulin-resistant premenopausal women.

Association of DRD2 and DRD3 polymorphisms with Parkinson's disease in a multiethnic consortium

OBJECTIVE

To examine genetic associations of polymorphisms in the dopamine receptor D2 (DRD2) and D3 (DRD3) genes with risk of Parkinson's disease (PD).

METHODS

The study included 1325 newly diagnosed patients with PD and 1735 controls from a consortium of five North American case-control studies. We collected risk factor information by in-person or telephone interview. Six DRD2 and two DRD3 polymorphisms were genotyped using a common laboratory. Odds ratios were estimated using logistic regression.

RESULTS

Among non-Hispanic whites, homozygous carriers of Taq1A DRD2 (rs1800497) polymorphism had an increased risk of PD compared to homozygous wildtype carriers (OR=1.5, 95% CI 1.0-2.3). In contrast, the direction of association for Taq1A polymorphism was opposite for African-Americans, showing an inverse association with PD risk (OR=0.10, 95% CI 0.2-0.7). Among white Hispanics who carried two alleles, the Ser9Gly DRD3 (rs6280) polymorphism was associated with a decreased risk of PD (OR=0.4, 95% CI 0.2-0.8). The inverse association of smoking with PD risk was not modified by any of the DRD2 or DRD3 polymorphisms.

CONCLUSIONS

DRD2 polymorphisms are unlikely to be true disease-causing variants; however, three DRD2 polymorphisms (including Taq1A) may be in linkage disequilibrium with possible disease associated variants in the DRD2-ANKK1-NCAM1-TTC12 gene cluster.

Coffee, ADORA2A, and CYP1A2: the caffeine connection in Parkinson's disease

BACKGROUND AND PURPOSE

In 1-methyl-4-phenyl 1,2,3,6-tetrahydropyridine animal models of Parkinson's disease (PD), caffeine protects neurons by blocking the adenosine receptor A2A (ADORA2A). Caffeine is primarily metabolized by cytochrome P450 1A2 (CYP1A2). Our objective was to examine whether ADORA2A and CYP1A2 polymorphisms are associated with PD risk or modify the caffeine-PD association.

METHODS

Parkinson's Epidemiology and Genetic Associations Studies in the United States (PEGASUS) included five population-based case-control studies. One laboratory genotyped four ADORA2A and three CYP1A2 polymorphisms in 1325 PD cases and 1735 age- and sex-matched controls. Information regarding caffeine (coffee) consumption and other lifestyle factors came from structured in-person or telephone interviews. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression.

RESULTS

Two ADORA2A polymorphisms were inversely associated with PD risk - rs71651683, a 5' variant (adjusted allelic OR = 0.51, 95% CI 0.33-0.80, permutation-adjusted P = 0.015) and rs5996696, a promoter region variant (adjusted OR for AC and CC genotypes compared with the AA wild-type genotype were 0.76 (95% CI 0.57-1.02) and 0.37 (95% CI 0.13-1.01), respectively (permutation-adjusted P for trend = 0.04). CYP1A2 polymorphisms were not associated with PD risk; however, the coffee-PD association was strongest among subjects homozygous for either variant allele rs762551 (P(interaction) = 0.05) or rs2470890 (P(interaction) = 0.04).

CONCLUSION

In this consortium study, two ADORA2A polymorphisms were inversely associated with PD risk, but there was weak evidence of interaction with coffee consumption. In contrast, the coffee-PD association was strongest among slow metabolizers of caffeine who were homozygous carriers of the CYP1A2 polymorphisms.

Effect of reproductive factors and postmenopausal hormone use on the risk of Parkinson disease

OBJECTIVE

Parkinson disease (PD) is less common in women possibly because of hormonal or reproductive influences. The objective of this study was to evaluate the associations of reproductive factors and postmenopausal hormone use with the risk of PD among postmenopausal women.

METHODS

Incident cases (n = 178) and randomly selected age-matched controls (n = 189) who were members of the Kaiser Permanente Medical Care Program (KPMCP) of Northern California participated in the study conducted during the years 1994 to 1995. Statistical analyses were carried out using logistic regression.

RESULTS

The association of postmenopausal hormone use with PD risk depended on the type of menopause. Among women with history of a hysterectomy with or without an oophorectomy, estrogen use alone was associated with a 2.6-fold increased risk (adjusted odds ratio (OR) 2.6, 95% CI: 1.1 to 6.1) and significant trends in the risk of PD were observed with increasing duration of estrogen use, but disease risk was not influenced by recency of use. In contrast, among women with natural menopause, no increased risk of PD was observed with hormone use (estrogen alone or a combined estrogen-progestin regimen). Early age at final menstrual period (44 years or younger) was associated with reduction in risk (adjusted OR 0.5, 95% CI: 0.3 to 1.0). Age at menarche and parity were not associated with the risk of PD.

CONCLUSION

Postmenopausal use of estrogen alone may increase the risk of Parkinson disease (PD) among women with a hysterectomy. Among women with natural menopause for whom the usual treatment is combined estrogen-progestin therapy, no increased risk of PD was observed.

Biomechanical analysis of failed sit-to-stand

Background sit-to-stand (STS) failure is a transient loss of balance that can engender falls among elders. The purpose of this paper is to describe the mechanisms whereby failed STS differs from successful STS. The authors compared successful STS from 11 normal elders to 20 "sitback" and 20 "step" type failed STS's in 13 subjects. Kinematic and kinetic data were incorporated into our 11-segment whole body model to estimate the net joint forces and torques and body segment momenta. Significant between group differences in the magnitude and timing of momentum generation and dissipation, knee extensor torques and the magnitude of the vertical ground reaction force were identified. Both types of failed sit-to-stand maneuvers are less energetic than successful rises. STS failures might result from either weakness or balance control and coordination impairment, or both, resulting in an insufficiently energetic effort. Further research is required to differentiate between these two possible sources of impairment. Determining the root cause of functional limitations is necessary to develop effective interventions.

Rehabilitation of balance in two patients with cerebellar dysfunction

The treatment of two patients with cerebellar dysfunction is described. One patient was a 36-year-old woman with a 7-month history of dizziness and unsteadiness following surgical resection of a recurrent pilocystic astrocytoma located in the cerebellar vermis. The other patient was a 48-year-old man with cerebrotendinous xanthomatosis (CTX) and diffuse cerebellar atrophy, and a 10-year history of progressive gait and balance difficulties. Each patient was treated with a 6-week course of physical therapy that emphasized the practice of activities that challenged stability. The patient with the cerebellar tumor resection also performed eye-head coordination exercises. Each patient had weekly therapy and performed selected balance retraining exercises on a daily basis at home. Measurements taken before and after treatment for each patient included self-perception of symptoms, clinical balance tests, and stability during selected standing and gait activities; for the patient with the cerebellar tumor resection, vestibular function tests and posturography were also performed. Both patients reported improvements in symptoms and demonstrated similar improvements on several kinematic indicators of stability during gait. The patient with the cerebellar tumor resection improved on posturography following treatment, whereas the patient with CTX improved on clinical balance tests. This case report describes two individualized treatment programs and documents functional improvements in two patients with different etiologies, durations, and clinical presentations of cerebellar dysfunction. The outcomes suggest that patients with cerebellar lesions, acute or chronic, may be able to learn to improve their postural stability.

Quantitative assessment of four men using above-elbow prosthetic control

We studied the relationship between kinematically unconstrained activities of daily living (ADL) tasks and a kinematically constrained task in above-elbow (AE) amputee subjects using myoelectrically controlled prostheses. Four men, 24 to 49 years old, with unilateral AE amputation wore a prosthesis interfaced to a programmable controller to emulate two different elbow control schemes, conventional velocity and a new "natural" controller. Subjects were timed during three ADL tasks--cutting meat, donning socks, and rolling dough--with both controllers. The prosthesis emulator was then connected to a crank device with a handle, and the subjects turned the crank from bottom to top positions in a vertical plane using each controller. Synergistic shoulder-elbow joint coordination required for crank turning was quantified as the maximum slope of the change in elbow torque versus the change in crank-angle. Performance between the two controllers differed significantly for the crank test but not for ADL tasks. One subject did not complete all crank turning tests. Positive canonical correlation of 0.77 was found between time and crank domain measures. We conclude that biomechanical assessments should be integrated with time-based clinical tests to comprehensively evaluate performance of AE amputee subjects with a myoelectric device.