Emulsions with unique properties from proteins as emulsifiers.

Many proteins are surface active molecules and form stable emulsions. In these emulsions, the protein covered oil droplets behave as sticky droplets even when they are ionically charged. As a result of the stickiness of the droplets the emulsions have gel-like properties. The stickiness is due to the multipolar nature of the proteins in contrast to the bipolar nature of surfactants or other amphiphilic compounds that form emulsions with repulsive droplets. Stable emulsions are also formed from particles like clays to which proteins are adsorbed. These hybrid compounds form even more stable emulsions with stronger elastic properties than clays and proteins on their own. These so called pickering emulsions have paste-like properties and do not flow. The scaffolding network of the crosslinked protein bilayers on the droplets is so strong that both the water and the oil can be removed from the emulsions by freeze drying without collapse of the scaffold. The resulting sponge can be used again for the uptake of both water and oil. Emulsions which are prepared from different proteins differ mainly in their elastic properties.

Exercise efficiency of low power output cycling.

Exercise efficiency at low power outputs, energetically comparable to daily living activities, can be influenced by homeostatic perturbations (e.g., weight gain/loss). However, an appropriate efficiency calculation for low power outputs used in these studies has not been determined. Fifteen active subjects (seven females, eight males) performed 14, 5-min cycling trials: two types of seated rest (cranks vertical and horizontal), passive (motor-driven) cycling, no-chain cycling, no-load cycling, cycling at low (10, 20, 30, 40 W), and moderate (50, 60, 80, 100, 120 W) power outputs. Mean delta efficiency was 57% for low power outputs compared to 41.3% for moderate power outputs. Means for gross (3.6%) and net (5.7%) efficiencies were low at the lowest power output. At low power outputs, delta and work efficiency values exceeded theoretical values. In conclusion, at low power outputs, none of the common exercise efficiency calculations gave values comparable to theoretical muscle efficiency. However, gross efficiency and the slope and intercept of the metabolic power vs mechanical power output regression provide insights that are still valuable when studying homeostatic perturbations.

Repeat traumatic brain injury in the juvenile rat is associated with increased axonal injury and cognitive impairments.

Among the enormous population of head-injured children and young adults are a growing subpopulation who experience repeat traumatic brain injury (RTBI). The most common cause of RTBI in this age group is sports-related concussions, and athletes who have experienced a head injury are at greater risk for subsequent TBI, with consequent long-term cognitive dysfunction. While several animal models have been proposed to study RTBI, they have been shown to either produce injuries too severe, were conducted in adults, involved craniotomy, or failed to show behavioral deficits. A closed head injury model for postnatal day 35 rats was established, and single and repeat TBI (1-day interval) were examined histologically for axonal injury and behaviorally by the novel object recognition (NOR) task. The results from the current study demonstrate that an experimental closed head injury in the rodent with low mortality rates and absence of gross pathology can produce measurable cognitive deficits in a juvenile age group. The introduction of a second injury 24 h after the first impact resulted in increased axonal injury, astrocytic reactivity and increased memory impairment in the NOR task. The histological evidence demonstrates the potential usefulness of this RTBI model for studying the impact and time course of RTBI as it relates to the pediatric and young adult population. This study marks the first critical step in experimentally addressing the consequences of concussions and the cumulative effects of RTBI in the developing brain.

Practice parameter update: evaluation and management of driving risk in dementia: report of the Quality Standards Subcommittee of the American Academy of Neurology.

OBJECTIVE: To review the evidence regarding the usefulness of patient demographic characteristics, driving history, and cognitive testing in predicting driving capability among patients with dementia and to determine the efficacy of driving risk reduction strategies. METHODS: Systematic review of the literature using the American Academy of Neurology's evidence-based methods. RECOMMENDATIONS: For patients with dementia, consider the following characteristics useful for identifying patients at increased risk for unsafe driving: the Clinical Dementia Rating scale (Level A), a caregiver's rating of a patient's driving ability as marginal or unsafe (Level B), a history of crashes or traffic citations (Level C), reduced driving mileage or self-reported situational avoidance (Level C), Mini-Mental State Examination scores of 24 or less (Level C), and aggressive or impulsive personality characteristics (Level C). Consider the following characteristics not useful for identifying patients at increased risk for unsafe driving: a patient's self-rating of safe driving ability (Level A) and lack of situational avoidance (Level C). There is insufficient evidence to support or refute the benefit of neuropsychological testing, after controlling for the presence and severity of dementia, or interventional strategies for drivers with dementia (Level U).

Intranasal insulin improves cognition and modulates beta-amyloid in early AD.

BACKGROUND: Reduced brain insulin signaling and low CSF-to-plasma insulin ratios have been observed in patients with Alzheimer disease (AD). Furthermore, intracerebroventricular or IV insulin administration improve memory, alter evoked potentials, and modulate neurotransmitters, possibly by augmenting low brain levels. After intranasal administration, insulin-like peptides follow extracellular pathways to the brain within 15 minutes. OBJECTIVE: We tested the hypothesis that daily intranasal insulin treatment would facilitate cognition in patients with early AD or its prodrome, amnestic mild cognitive impairment (MCI). The proportion of verbal information retained after a delay period was the planned primary outcome measure. Secondary outcome measures included attention, caregiver rating of functional status, and plasma levels of insulin, glucose, beta-amyloid, and cortisol. METHODS: Twenty-five participants were randomly assigned to receive either placebo (n = 12) or 20 IU BID intranasal insulin treatment (n = 13) using an electronic atomizer, and 24 participants completed the study. Participants, caregivers, and all clinical evaluators were blinded to treatment assignment. Cognitive measures and blood were obtained at baseline and after 21 days of treatment. RESULTS: Fasting plasma glucose and insulin were unchanged with treatment. The insulin-treated group retained more verbal information after a delay compared with the placebo-assigned group (p = 0.0374). Insulin-treated subjects also showed improved attention (p = 0.0108) and functional status (p = 0.0410). Insulin treatment raised fasting plasma concentrations of the short form of the beta-amyloid peptide (A beta 40; p = 0.0471) without affecting the longer isoform (A beta 42), resulting in an increased A beta 40/42 ratio (p = 0.0207). CONCLUSIONS: The results of this pilot study support further investigation of the benefits of intranasal insulin for patients with Alzheimer disease, and suggest that intranasal peptide administration may be a novel approach to the treatment of neurodegenerative disorders.

Differential modulation of plasma beta-amyloid by insulin in patients with Alzheimer disease.

BACKGROUND: Hyperinsulinemia and insulin resistance are risk factors for memory impairment and Alzheimer disease (AD). Insulin regulates levels of the amyloid beta-peptide (Abeta) in vitro in neuronal cultures and in vivo in the CSF of normal older adults. OBJECTIVE: To determine whether insulin affected plasma Abeta levels and whether such effects differed for patients with AD compared with normal older adults. METHODS: Fifty-nine patients with AD and 50 healthy older adults each received infusions of saline and of insulin (1.0 mU.kg(-1).min(-1)) with accompanying dextrose to maintain euglycemia. A subset of participants (19 AD, 12 normal) received two additional conditions, in which insulin was infused at a lower (0.33 mU.kg(-1).min(-1)) and higher (1.67 mU.kg(-1).min(-1)) rate. Plasma insulin and Abeta were measured after 120 minutes of infusion. RESULTS: Adults with AD had higher plasma insulin vs normal adults at the two higher infusion rates, despite receiving comparable amounts of insulin. For normal adults, insulin reduced plasma Abeta levels at the middle (1.0 mU.kg(-1).min(-1)) dose, with attenuated effects at lower and higher doses. In contrast, for patients with AD, insulin raised plasma Abeta levels at the two higher doses (1.0 and 1.67 mU.kg(-1).min(-1)). CONCLUSIONS: These results suggest that patients with Alzheimer disease (AD) have reduced insulin clearance and insulin-provoked plasma amyloid beta-peptide (Abeta) elevation. Abnormal regulation of peripheral Abeta by insulin may contribute to AD risk.

Effects of intranasal insulin on cognition in memory-impaired older adults: modulation by APOE genotype.

Raising insulin acutely in the periphery and in brain improves verbal memory. Intranasal insulin administration, which raises insulin acutely in the CNS without raising plasma insulin levels, provides an opportunity to determine whether these effects are mediated by central insulin or peripheral processes. Based on prior research with intravenous insulin, we predicted that the treatment response would differ between subjects with (epsilon4+) and without (epsilon4-) the APOE-epsilon4 allele. On separate mornings, 26 memory-impaired subjects (13 with early Alzheimer's disease and 13 with amnestic mild cognitive impairment) and 35 normal controls each underwent three intranasal treatment conditions consisting of saline (placebo) or insulin (20 or 40 IU). Cognition was tested 15 min post-treatment, and blood was acquired at baseline and 45 min after treatment. Intranasal insulin treatment did not change plasma insulin or glucose levels. Insulin treatment facilitated recall on two measures of verbal memory in memory-impaired epsilon4- adults. These effects were stronger for memory-impaired epsilon4- subjects than for memory-impaired epsilon4+ subjects and normal adults. Unexpectedly, memory-impaired epsilon4+ subjects showed poorer recall following insulin administration on one test of memory. These findings suggest that intranasal insulin administration may have therapeutic benefit without the risk of peripheral hypoglycemia and provide further evidence for apolipoprotein E (APOE) related differences in insulin metabolism.

Safety and efficacy of repeat transradial access for cardiac catheterization procedures.

To determine the safety and efficacy of repeat transradial cardiac catheterization, 1,362 consecutive transradial procedures were examined. Repeat transradial procedures were identified (group I, n = 73) and compared with index procedures (group II, n = 1,289). Baseline patient characteristics, procedure success rates (100% vs. 97.9%; P = NS), complication rates (0% vs. 0.08%; P = NS), and procedure times (23.9 +/- 27.3 min vs. 18.2 +/- 14.7 min; P = NS) were similar between groups. This study suggests that repeat transradial catheterization procedures can be performed safely and successfully in appropriately selected patients.

Adjunctive therapies in the cath lab. Use of combination glycoprotein IIb/IIIa inhibitor and direct thrombin inhibitor drugs to support percutaneous coronary stent placement in a patient with renal insufficiency and heparin-induced thrombocytopenia.

An 81-year-old woman with a history of prior coronary artery bypass surgery, heparin-induced thrombocytopenia with "white clot" syndrome, and renal insufficiency presented with unstable angina. She was referred for cardiac catheterization. Complex percutaneous revascularization of the native circumflex coronary artery was performed using stents. A combination of tirofiban and lepirudin was used with dosing adjusted for renal insufficiency. The hospital course was uncomplicated and the patient was discharged on the fourth hospital day. This is only the second report of the combination use of direct thrombin inhibitor and glycoprotein IIb/IIIa receptor inhibitor.

Transradial cardiac catheterization in elderly patients.

The safety and efficacy of transradial cardiac catheterization in elderly patients is unknown. This study examines procedure success rates for transradial catheterization in appropriately selected patients < 70 (n = 195) and >/= 70 (n = 83) years old. Elderly patients were less likely to be selected for the transradial approach (46% vs. 61%; P = 0.05). Although patients >/= 70 years old were more often female (39.7% vs. 24.1%; P = 0.008) and had a smaller body surface area (1.89 +/- 0.18 vs. 2.01 +/- 0.24 m2; P = 0. 001), procedure success rates did not differ (95.1% vs. 94.8%; P = NS). Procedure-related variables including procedure time (15.4 +/- 12.6 vs. 16.1 +/- 11.6 min; P = NS), amount of radiographic contrast (90.1 +/- 31.9 vs. 86.4 +/- 29.8 cc; P = NS), and number of catheters used (1.5 +/- 0.9 vs. 1.5 +/- 0.7; P = NS) were similar between groups. We conclude that transradial catheterization can be safely and effectively performed in selected elderly patients. Cathet. Cardiovasc. Intervent. 51:287-290, 2000.

An unusual complication during deployment of a Multi-Link stent.

The use of intracoronary stents has greatly impacted on the practice of interventional cardiology. Complications due to equipment failure during deployment of stents are rare but potentially serious. We report a case of a malfunctioning Multi-Link delivery system and the successful treatment of the resulting complications.

Extensive coronary dissection caused by balloon rupture at high pressure during stent deployment.

A patient with severe stenosis of the right coronary artery underwent successful stent placement. During high pressure postdilatation, the balloon ruptured, causing an extensive proximal dissection of the right coronary artery managed with the deployment of several additional stents. Strategies aimed at avoiding or minimizing the consequences of high pressure balloon rupture are discussed.

Peripheral vascular complications of coronary angioplasty by the femoral and brachial techniques.

In order to monitor the incidence and types of peripheral vascular complications in a single institution, we prospectively entered 1,579 coronary angioplasty cases into a computer data base during the years 1991 and 1992. Various periprocedural risk factors were analyzed. The patients were followed closely to identify complications that occurred outside the laboratory or after discharge from the hospital. Peripheral vascular complications occurred in 37 patients (2.37%) and included hematoma 20 (1.27%), retroperitoneal bleeding 7 (.44%), false aneurysm 6 (.38%), occlusion 1 (.06%), infection 2 (.13%), and cholesterol emboli 1 (.06%). Risk factors for complications by multivariate analysis were older age, female gender, and clinical evidence of peripheral vascular disease. Other factors potentially related to vascular trauma or bleeding tendency that were not risk factors in this series were clinical presentation, use of heparin or thrombolytic agents, blood clotting parameters, and arterial sheath size. There was no significant difference between the femoral and brachial approaches in frequency of complications (2.5% vs. 1.6%), but femoral complications tended to carry greater morbidity.

Angioplasty of a large aortocoronary bypass graft utilizing a single oversized balloon catheter.

Angioplasty of large saphenous vein grafts may present problems because of unavailability of adequately sized balloon dilatation catheters. We report a case of successful PTCA of a left anterior descending graft by using a 5 mm balloon and a standard 8F guiding catheter.

Acute renal failure following low osmolality radiocontrast dye.

It is hoped that recently released low osmolality radiocontrast agents (RCAs) will have a lower nephrotoxic potential, since dye nephropathy may be related to hyperosmolality. We report here 2 cases of typical oliguric dye nephropathy in patients without risk factors for dye nephropathy. These cases show that these new agents do have nephrotoxic potential.

Rest and exercise hemodynamics following aortic valve replacement. A comparison between 19 and 21 mm Ionescu-Shiley pericardial and Carpentier-Edwards porcine valves.

When aortic valve replacement is performed in a patient with a small anulus, significant obstruction of the left ventricular outflow tract may remain. Most prostheses are obstructive in the smaller sizes, and enlargement of the aortic anulus may be required to allow placement of a larger valve. To evaluate the hemodynamic performance of two commonly used tissue prostheses, the Ionescu-Shiley pericardial and Carpentier-Edwards porcine valves, 22 patients with either the 19 or 21 mm size were electively studied at rest and after exercise at a mean of 15 months after operation. The resting mean transvalvular gradient for 19 mm Ionescu-Shiley pericardial valves (n = 7), 10.6 +/- 9.2 mm Hg, was significantly lower than that for 19 mm Carpentier-Edwards valves (n = 3), 33.3 +/- 2.1 mm Hg, p less than 0.01. Following exercise, the mean gradient for 19 mm Ionescu-Shiley pericardial valves rose only to 13.8 +/- 8.5 mm Hg. No exercise data were available for the 19 mm Carpentier-Edwards valve. Among patients with 21 mm Ionescu-Shiley pericardial valves (n = 7), the mean transvalvular gradient at rest was 5.6 +/- 9.5 mm Hg, not significantly different from that of patients with 21 mm Carpentier-Edwards valves (n = 5), 9.8 +/- 18.3 mm Hg. After exercise, the gradients rose to 16.0 +/- 10.0 mm Hg and 25.5 +/- 23.8 mm Hg for the Ionescu-Shiley pericardial and Carpentier-Edwards valves, respectively (no statistical significance). Cardiac index was not different between groups. Gradients were not significantly higher in patients with body surface areas greater than 1.5 m2. It is concluded that the 19 and 21 mm Ionescu-Shiley pericardial valves possess excellent hemodynamics, even after exercise. This valve appears hemodynamically superior to the Carpentier-Edwards valve, particularly in the 19 mm size. Procedures to enlarge the aortic anulus are usually unnecessary when small Ionescu-Shiley pericardial valves are used, even in patients who have large body surface areas.

Electrocardiographic criteria for the diagnosis of anterior myocardial infarction: importance of the duration of precordial R waves.

A systematic evaluation of a large number of electrocardiographic (ECG) variables that might be useful for diagnosing anterior myocardial infarction (MI) is reported. Previous anterior MI was shown to be present or absent by cardiac catheterization in 199 patients. The best discriminator between cases and noncases of anterior MI in most patients is the presence of a Q wave of any magnitude or an initial R wave less than 20 ms in lead V2. In patients with ECG evidence of associated left ventricular or type C right ventricular enlargement, the more stringent criterion of a Q wave of any magnitude in lead V2 yielded the optimal combination of sensitivity and specificity for diagnosing anterior MI. The diagnostic performance of the proposed criteria for anterior MI is superior to that of more traditional criteria that use measurements of the absolute and relative amplitudes of precordial R waves.