Karen E. Hall

Voltage-dependent calcium currents are enhanced in dorsal root ganglion neurones from the Bio Bred/Worchester diabetic rat.

1. Whole‐cell, high‐threshold, voltage‐dependent calcium currents (ICa) were enhanced in acutely dissociated, capsaicin‐sensitive dorsal root ganglion neurones from diabetic Bio Bred/Worchester (BB/W) rats, compared with those from age‐matched, non‐diabetic controls. The magnitude of the enhancement increased with the duration of diabetes, and reached significance at diabetic durations of 6 months (diabetic: 6.3 +/‐ 0.4 nA; current density (CD), 157 +/‐ 12 pA pF‐1; means +/‐ S.E.M., n = 9, P < 0.01; control: 3.9 +/‐ 0.6 nA; CD, 116 +/‐ 11 pA pF‐1; n = 18) and 8 months (diabetic: 7.6 +/‐ 0.4 nA; CD, 177 +/‐ 25 pA pF‐1; n = 11, P < 0.005; control: 5.1 +/‐ 0.5 nA; CD, 111 +/‐ 26 pA pF‐1; n = 15). Low‐threshold, voltage‐dependent ICa were also enhanced in neurones from animals diabetic for 8 months (diabetic: 2.5 +/‐ 0.7 nA, n = 4, P < 0.05; control: 0.7 +/‐ 0.5 nA, n = 6). 2. The ICa enhancement was prevented by long‐term treatment of diabetic animals with an aldose reductase inhibitor (ARI; peak ICa at 6 months: 4.41 +/‐ 0.48 nA, n = 2; at 8 months: 4.32 +/‐ 0.60 nA, n = 9). 3. The ICa enhancement was not due to a shift in the voltage dependence of either the current‐voltage relationship or steady‐state inactivation. 4. The L channel antagonist nifedipine and preferential N channel antagonist omega‐conotoxin GVIA (omega‐CgTX) caused a greater inhibition of high‐threshold ICa in diabetic neurones compared with controls (nifedipine: control: 25 +/‐ 3%, n = 26; diabetic: 36 +/‐ 7%, n = 11; omega‐CgTX: control: 40 +/‐ 4%, n = 21; diabetic: 50 +/‐ 7%, n = 7). Diabetic neurones also demonstrated a significantly greater residual current (2.44 +/‐ 0.34 nA, n = 7) in the presence of both antagonists vs. controls (1.28 +/‐ 0.30 nA, n = 8, P < 0.05), suggesting that N‐, L‐ and additional non‐N‐, non‐L‐type high‐threshold ICa were enhanced.

Serum from Patients with Type 2 Diabetes with Neuropathy Induces Complement-independent, Calcium-dependent Apoptosis in Cultured Neuronal Cells

We hypothesized that sera from type 2 diabetic patients with neuropathy contains an autoimmune immunoglobulin that promotes complement-independent, calcium-dependent apoptosis in neuronal cell lines. Neuronal cells were cultured in the presence of complement-inactivated sera obtained from patients with type 2 diabetes with and without neuropathy and healthy adult control patients. Serum from diabetic patients with neuropathy was associated with a significantly greater induction of apoptosis, compared to serum from diabetic patients without neuropathy and controls. In the presence of calcium channel antagonists, induction of apoptosis was reduced by approximately 50%. Pretreatment of neuronal cells with serum from diabetic patients with neuropathy was associated with a significant increase in elevated K+-evoked cytosolic calcium concentration. Serum-induced enhancement in cytosolic calcium and calcium current density was blocked by treatment with trypsin and filtration of the serum using a 100,000-kd molecular weight filter. Treatment with an anti-human IgG antibody was associated with intense fluorescence on the surface of neuronal cells exposed to sera from patients with type 2 diabetes mellitus with neuropathy. We conclude that sera from type 2 diabetic patients with neuropathy contains an autoimmune immunoglobulin that induces complement-independent, calcium-dependent apoptosis in neuronal cells.

Opiate-mediated inhibition of calcium signaling is decreased in dorsal root ganglion neurons from the diabetic BB/W rat.

The effect of diabetes mellitus on opiate-mediated inhibition of calcium current density (I(D Ca) [pA pF-1]) and cytosolic calcium response ([Ca2+]i nM) to depolarization with elevated KCl and capsaicin was assessed. Experiments were performed on isolated, acutely dissociated dorsal root ganglion (DRG) neurons from diabetic, BioBreeding/Worcester (BB/W) rats and age-matched control animals. Sciatic nerve conduction velocity was significantly decreased in diabetic animals compared to controls. Mean I(DCa) and [Ca2+]i responses to capsaicin and elevated KCl recorded in DRGs from diabetic animals were significantly larger than those recorded in DRG neurons from controls. In neurons from diabetic animals, the opiate agonist dynorphin A (Dyn A; 1, 3, and 5 microM) had significantly less inhibitory effect on I(D Ca) and KCl-induced [Ca2+]i responses compared to controls. Omega-conotoxin GVIA (omega-CgTX; 10 microM) and pertussis toxin (PTX; 250 ng ml-1) abolished Dyn A-mediated inhibition of I(DCa) and [Ca2+]i in control and diabetic neurons, suggesting that Dyn A modulated predominantly N-type calcium channels coupled to opiate receptors via PTX-sensitive (Gi/o) inhibitory G proteins. These results suggest that opiate-mediated regulation of PTX-sensitive, G protein-coupled calcium channels is diminished in diabetes and that this correlates with impaired regulation of cytosolic calcium.

A vertically integrated geriatric curriculum improves medical student knowledge and clinical skills

The objective of this study was to determine the effect of a vertically integrated curriculum intervention on the geriatric knowledge and performance in clinical skills of third‐year medical students. This observational cohort study conducted at the University of Michigan Medical School evaluates the performance of 622 third‐year medical students from the graduating class years of 2004 through 2007. An integrated curriculum intervention was developed and implemented for the class of 2006. Its elements included identification and tracking of geriatric learning outcomes in an individualized Web‐based student portfolio, integration of geriatric content into preclinical courses, development of a geriatric functional assessment standardized patient instructor, and an experience in a geriatrics clinic during the ambulatory component of the third‐year internal medicine clerkship. Medical student performance was assessed on a geriatric knowledge test and during a geriatric functional assessment station administered during an Observed Structured Clinical Examination (OSCE) at the beginning of the fourth year. Student performance on the geriatric functional assessment OSCE station progressively improved from pre‐intervention performance (mean performance±standard deviation 43±15% class of 2005, 62 + 15% class of 2006, 78±10% class of 2007; analysis of variance, P<.001). Similarly, student performance on the geriatric knowledge test was significantly better for the classes of 2006 and 2007 than for the class of 2005 (model F ratio=4.72; P<.001). In conclusion, an integrated approach to incorporating new educational geriatric objectives into the medical school curriculum leads to significant improvements in medical student knowledge and in important clinical skills in the functional assessment of older patients.

Treatment of aged rat sensory neurons in short-term, serum-free culture with nerve growth factor reverses the effect of aging on neurite outgrowth, calcium currents, and neuronal survival.

Impaired NGF production and release has been documented in aged animals, suggesting that decreased NGF receptor stimulation may be one factor contributing to neuronal dysfunction with aging. Other studies have suggested that aging may be associated with impaired intracellular responses to NGF. Because aging-associated neuronal dysfunction contributes to morbidity and mortality in the geriatric population, it is important to determine whether the effects of aging on sensory neuron function and survival are reversible. In the present study, we observed significantly decreased neurite outgrowth and neuronal survival in short-term cultures (0-96 h) of dorsal root ganglion (DRG) neurons from aged (>22 months) Fisher 344 x Brown Norway F1 hybrid rats, compared to young (4-6 month) and middle-aged (14 month) animals. From 24 to 96 h in culture, diminished survival of aged neurons appeared to be due to an increased rate of apoptotic cell death. DRG neurons from aged animals also exhibited significantly decreased whole cell, high-threshold voltage-dependent calcium currents, with a larger proportion of L-type current, compared to youthful and middle-aged animals. Treatment of aged DRG neurons with NGF restored neurite outgrowth, neuronal survival and calcium current amplitude and subtype distribution to those observed in youthful DRG neurons.

Development of a standardized patient instructor to teach functional assessment and communication skills to medical students and house officers

Professional societies have called for increased geriatrics training for all medical students and physicians.

Analytic morphomics corresponds to functional status in older patients

BACKGROUND Older patients account for nearly half of the United States surgical volume, and age alone is insufficient to predict surgical fitness. Various metrics exist for risk stratification, but little work has been done to describe the association between measures. We aimed to determine whether analytic morphomics, a novel objective risk assessment tool, correlates with functional measures currently recommended in the preoperative evaluation of older patients. MATERIALS AND METHODS We retrospectively identified 184 elective general surgery patients aged >70 y with both a preoperative computed tomography scan and Vulnerable Elderly Surgical Pathways and outcomes Assessment within 90 d of surgery. We used analytic morphomics to calculate trunk muscle size (or total psoas area [TPA]) and univariate logistic regression to assess the relationship between TPA and domains of geriatric function mobility, basic and instrumental activities of daily living (ADLs), and cognitive ability. RESULTS Greater TPA was inversely correlated with impaired mobility (odds ratio [OR] = 0.46, 95% confidence interval [CI] 0.25-0.85, P = 0.013). Greater TPA was associated with decreased odds of deficit in any basic ADLs (OR = 0.36 per standard deviation unit increase in TPA, 95% CI 0.15-0.87, P <0.03) and any instrumental ADLs (OR = 0.53, 95% CI 0.34-0.81; P <0.005). Finally, patients with larger TPA were less likely to have cognitive difficulty assessed by Mini-Cog scale (OR = 0.55, 95% CI 0.35-0.86, P <0.01). Controlling for age did not change results. CONCLUSIONS Older surgical candidates with greater trunk muscle size, or greater TPA, are less likely to have physical impairment, cognitive difficulty, or decreased ability to perform daily self-care. Further research linking these assessments to clinical outcomes is needed.

Diabetic neuropathy: inhibitory G protein dysfunction involves PKC‐dependent phosphorylation of Goα

We examined the hypothesis that decreased inhibitory G protein function in diabetic neuropathy is associated with increased protein kinase C (PKC)‐dependent phosphorylation of the Goα subunit. Streptozotocin‐induced diabetic rats were studied between 4 and 8 weeks after onset of diabetes and compared with aged‐matched healthy animals as controls. Opioid‐mediated inhibition of forskolin‐stimulated cyclic AMP was significantly less in dorsal root ganglia (DRGs) from diabetic rats compared with controls. Activation of PKC in DRGs from control rats was associated with a significant decrease in opioid‐mediated inhibition of forskolin‐stimulated cyclic AMP that was similar to the decrease in inhibition observed in DRGs from diabetic rats. Both basal and PKC‐mediated labeling of Goα with 32Pi was significantly less in DRGs from diabetic rats, supporting increased endogenous PKC‐dependent phosphorylation of Goα. Probing of immunoprecipitated Goα with an anti‐phospho‐serine/threonine specific antibody revealed a significant increase in baseline phosphorylation in diabetic DRGs. Activation of PKC produced a significant increase in phosphorylation in control DRGs but no significant increase in Goα in diabetic DRGs. Phosphorylation of PKC‐α was increased, PKC‐βII was unchanged and PKC‐δ decreased in diabetic DRGs. These results suggest that diminished inhibitory G protein function observed in DRGs neurons from diabetic rats involves an isoform‐specific PKC‐dependent pathway.

Failure of nimodipine to prevent or correct the long-term nerve conduction defect and increased neuronal Ca2+-currents in the diabetic BB/W-rat

It has been suggested that L-type Ca2+ channel antagonists exert a beneficial effect on nerve conduction velocity (NCV) slowing in short-term experimental diabetic neuropathy. We examined the effects of long-term treatment with the L-channel blocker, nimodipine, on two aspects of neuronal function previously documented to be abnormal in the spontaneously diabetic BB/W-rat: nerve conduction velocity and calcium influx in dorsal root ganglion (DRG) neurons. Treatment with 20 mg/kg nimodipine i.p. every 48 h from onset of diabetes for 6 months led to a transient, non-significant (30%) improvement in NCV. Intervention with the same regimen from 3 to 6 months of diabetes had no corrective effect on the already established NCV defect. Voltage activated calcium currents were recorded in isolated DRG neurons from nimodipine-treated and untreated diabetic and non-diabetic age-matched BB/W control rats. The peak high-threshold calcium current density (IDCa, pA/pF) was significantly larger in non-treated diabetic rats compared with control rats (157 +/- 12 vs. 66 +/- 5.5 (P < or = 0.05)). Long-term treatment with nimodipine was associated with a non-significant (28%) decrease (112 +/- 29) in the IDCa compared with non-treated diabetic rats. We conclude that L-channel mediated perturbations of cytosolic Ca2+ levels are only of minor pathophysiologic significance in the development of chronic diabetic neuropathy.

Estimating Risk of Postsurgical General and Geriatric Complications Using the VESPA Preoperative Tool

Importance As greater numbers of older patients seek elective surgery, one approach to preventing postoperative complications is enhanced assessment of risks during preoperative evaluation. Objective To determine whether a geriatric assessment tool can be implemented in a preoperative clinic and can estimate risk of postoperative complications. Design, Setting, and Participants In this prospective cohort study, patients 70 years of age or older were assessed in a preoperative clinic for elective surgery from July 9, 2008, to January 5, 2011. Patients were screened using the Vulnerable Elders Surgical Pathways and Outcomes Assessment (VESPA) tool developed for this study. Patients were assessed on 5 preoperative activities of daily living recommended by the American College of Surgeons (bathing, transferring, dressing, shopping, and meals), history of falling or gait impairment, and depressive symptoms (2-item Patient Health Questionnaire). Patients also underwent a brief cognitive examination (Mini-Cog) and gait and balance assessment (Timed Up and Go test). A novel question was also asked as to whether patients expected they could manage themselves alone after discharge. Comorbidities and work-related relative value units (categorized into low, moderate, and high tertiles) were also collected. Multivariable logistic regression was performed to estimate risk of postoperative complications. Sustainability of VESPA over time was also evaluated. Medical record review was performed from December 11, 2012, to October 2, 2015, and data analysis was performed from November 15, 2015, to May 18, 2016. Main Outcomes and Measures Postoperative surgical and geriatric complications. Results Of the 770 patients evaluated, 736 (384 women and 352 men; mean [SD] age, 77.7 [5.7] years) underwent 740 operative procedures; of these patients, 711 had complete data for multivariable analysis. In our sample, 105 patients (14.3%) reported 1 or more difficulties with the 5 activities of daily living, and 270 of 707 patients (38.2%) foresaw themselves unable to manage self-care alone. A total of 131 of 740 patients had geriatric complications, and 114 of 740 patients had surgical complications; 187 of 740 patients (25.3%) had either geriatric or surgical complications. On multivariable analysis, the number of difficulties with activities of daily living (odds ratio [OR], 1.3; 95% CI, 1.0-1.6), anticipated difficulty with postoperative self-care (OR, 1.6; 95% CI, 1.0-2.2), Charlson Comorbidity score of 2 or more vs less than 2 (OR, 1.5; 95% CI, 1.0-2.3), male sex (OR, 1.6; 95% CI, 1.1-2.3), and work-related relative value units (moderate vs low: OR, 1.9; 95% CI, 1.1-3.3; high vs low: OR, 8.8; 95% CI, 5.3-14.5) were independently associated with postoperative complications (overall model area under the receiver operating characteristic curve, 0.77). With these results, a whole-point VESPA score used alone to estimate risk of complications also demonstrated excellent fit (area under the curve, 0.76). Conclusions and Relevance Preoperative assessment of older geriatric patients is feasible in the general preoperative clinic and can help identify patients at higher risk of postoperative complications.