A new high-density (25 electrodes/mm²) penetrating microelectrode array for recording and stimulating sub-millimeter neuroanatomical structures

OBJECTIVE

Among the currently available neural interface devices, there has been a need for a penetrating electrode array with a high electrode-count and high electrode-density (the number of electrodes/mm(2)) that can be used for electrophysiological studies of sub-millimeter neuroanatomical structures. We have developed such a penetrating microelectrode array with both a high electrode-density (25 electrodes/mm(2)) and high electrode-count (up to 96 electrodes) for small nervous system structures, based on the existing Utah Slanted Electrode Array (USEA). Such high electrode-density arrays are expected to provide greater access to nerve fibers than the conventionally spaced USEA especially in small diameter nerves.

APPROACH

One concern for such high density microelectrode arrays is that they may cause a nerve crush-type injury upon implantation. We evaluated this possibility during acute (<10 h) in vivo experiments with electrode arrays implanted into small diameter peripheral nerves of anesthetized rats (sciatic nerve) and cats (pudendal nerve).

MAIN RESULTS

Successful intrafascicular implantation and viable nerve function was demonstrated via microstimulation, single-unit recordings and histological analysis. Measurements of the electrode impedances and quantified electrode dimensions demonstrated fabrication quality. The results of these experiments show that such high density neural interfaces can be implanted acutely into neural tissue without causing a complete nerve crush injury, while mediating intrafascicular access to fibers in small diameter peripheral nerves.

SIGNIFICANCE

This new penetrating microelectrode array has characteristics un-matched by other neural interface devices currently available for peripheral nervous system neurophysiological research.

The emergent surgical airway: cricothyrotomy vs. tracheotomy

The American Society of Anesthesiologists difficult airway algorithm identifies two acceptable emergency surgical airways in the 'cannot intubate, cannot ventilate' scenario: cricothyrotomy and tracheotomy. Little has been published regarding the emergency surgical airway practices at different institutions. The authors investigated whether the primary choice of emergency surgical airway at a major level I trauma centre was cricothyrotomy or tracheotomy. A retrospective chart review was conducted of emergency airways performed over 6 years using relevant current procedural terminology codes. The electronic medical records obtained were reviewed to ensure accurate coding and verify the emergent nature of the procedure. Over the study period, there were 4312 documented emergent airways. 3197 (74.1%) were field intubated by paramedics, 1081 (25.1%) were hospital intubated by anaesthesia, 34 (0.008%) required emergency surgical access of which 24 were tracheotomies and 10 cricothyrotomies. Despite the emphasis in resident training and Advanced Trauma Life Support, there was a paucity of cricothyrotomies during the study period. At the authors' institution, tracheotomy is preferentially used as the emergency surgical airway. A multicentre prospective study is recommended to evaluate current practice in emergency surgical airway and to include the emergency open tracheotomy in residency training and continuing education if needed.

Socio-economic status influences blood pressure control despite equal access to care

OBJECTIVE

Denmark has a health care system with free and equal access to care irrespective of age and socio-economic status (SES). We conducted a cross-sectional study to investigate a possible association between SES and blood pressure (BP) control of hypertensive patients treated in general practice.

METHODS

We enrolled 184 general practices and 5260 hypertensive patients. The general practitioners reported information about BP and diagnosis of diabetes. Information about education, income, antihypertensive drug treatment and other co-morbidity was retrieved from relevant registers from Statistics Denmark. The outcome measure was BP control defined as BP <140/90 mmHg in general and <130/80 mmHg in diabetics.

RESULTS

Patients <65 years and with an educational level of 10-12 years had increased odds ratio (OR) of BP control compared to patients with an educational level <10 years. Patients ≥65 years had increased OR of BP control if they were married/cohabiting as compared to being single, whereas education and income had no impact in this age group. Diabetics had significantly reduced odds of BP control irrespective of age, educational or income level.

CONCLUSIONS

Despite equal access to care for all patients, SES had significant impact on BP control in this survey. Diabetes and cardiovascular disease also had a substantial influence irrespective of age, educational and income level.

Sensory phenotypes in patients with peripheral neuropathic pain evaluated with quantitative sensory testing

Background

In patients with neuropathic pain, Quantitative Sensory Testing (QST) can define different sensory phenotypes thought to be related to different underlying mechanisms. One phenotype with abnormal sensitization of cutaneous nociceptors has been termed irritable nociceptors.

Methods

This study is a part of a randomized, double-blind, placebo controlled, crossover trial with the anticonvulsant oxcarbazepine. The study is ongoing. In this report, baseline QST measures from patients with peripheral neuropathic pain due to either polyneuropathy (PNP) or peripheral nerve injury (PNI) are analyzed. QST evaluates thresholds for cold and heat detection (CDT, WDT), thermal pain (CPT, HPT), vibration (VDT), pin prick, mechanical detection and pressure pain. Furthermore, wind-up ratio and dynamic mechanical allodynia (DMA) are evaluated. Patients with irritable nociceptors are defined as patient with normal CDT and WDT and either mechanical or thermal allodynia or hyperalgesia.

Results

By March 2012, 28 patients with PNI and 24 with PNP were included. There was no difference in pain duration (66.2 (53.7) vs. 64.0 (43.3) months, p = 0.87) or pain intensity (NRS, 0 10) (6.6 (1.6) vs. 6.3 (1.7), p = 0.54), but patients with PNI were significantly younger (48.8 (15.1) years) compared to patients with PNP (62.4 (8.5) years), p < 0.001. The percentage of irritable nociceptors in the PNI group was 39.3% and in the PNP group 29.2% (p = 0.44). The percentage of patients with DMA was 39.3% and 33.3%, respectively (p = 0.66). Significantly more patients with PNI had thermal allodynia (28.6% vs. 0%, p = 0.005), 6 reported cold allodynia and 4 heat allodynia.

Conclusion

Preliminary results show that there was no significant difference in percentage of irritable nociceptors between the two groups, but more patients with PNI had thermal allodynia.

Treatment of 5413 hypertensive patients: a cross-sectional study

BACKGROUND

Most hypertensive patients are managed in primary care in Denmark, but previous studies have shown that only 21-43% of hypertensive patients achieve optimal blood pressure (BP) control. Antihypertensive drug treatment, risk factors and cardiovascular disease (CVD) are some of the important factors to consider when optimizing the individual treatment strategy in hypertensive patients.

OBJECTIVE

To examine treatment of BP according to Danish guidelines (BP < 140/90 mmHg generally and <130/80 mmHg for diabetics) in a population from general practice in relation to risk factors, CVD and diagnosis of diabetes.

METHODS

A cross-sectional study comprising 184 practices and 5413 hypertensive patients was carried out in Denmark. The general practitioners filled in information on each patient's risk factors, CVD and antihypertensive drug treatment. Patients filled in a questionnaire on risk factors. The outcome measures were optimal BP control according to Danish guidelines and antihypertensive drug treatment.

RESULTS

Mean patient age was 65.9 years [95% confidence interval (CI): 65.6-66.1]. Optimal BP control was achieved in 29.1% (95% CI: 27.9-30.3) of the study population. Among 842 diabetics with or without CVD, optimal BP control was achieved in 10.9% (95% CI: 8.8-10.3), while 38.7% (35.5-41.9) of patients with CVD achieved optimal BP control. The majority of all patients were treated with 1 (32.5%, 95% CI: 32.5 (31.3-33.8)) or two antihypertensive drugs (39.0%, 95% CI: 38.2-40.8). In hypertensive diabetics, 17.7% were not treated with an angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker.

CONCLUSION

In general practice, the proportion of hypertensive patients achieving optimal BP control is inadequate. The majority of hypertensive patients are treated with only one or two antihypertensive drugs.

Considerable variation in the concentration of osteopontin in human milk, bovine milk, and infant formulas

Osteopontin (OPN) is a multifunctional bioactive protein that is implicated in numerous biological processes such as bone remodeling, inhibition of ectopic calcification, and cellular adhesion and migration, as well as several immune functions. Osteopontin has cytokine-like properties and is a key factor in the initiation of T helper 1 immune responses. Osteopontin is present in most tissues and body fluids, with the highest concentrations being found in milk. In the present study, ELISA for human and bovine milk OPN were developed and OPN concentration in human breast milk, bovine milk, and infant formulas was measured and compared. The OPN concentration in human milk was measured to approximately 138 mg/L, which corresponds to 2.1% (wt/wt) of the total protein in human breast milk. This is considerably higher than the corresponding OPN concentrations in bovine milk (approximately 18 mg/L) and infant formulas (approximately 9 mg/L). Moreover, bovine milk OPN is shown to induce the expression of the T helper 1 cytokine IL-12 in cultured human lamina propria mononuclear cells isolated from intestinal biopsies. Finally, the OPN concentration in plasma samples from umbilical cords, 3-mo-old infants, and pregnant and nonpregnant adults was measured. The OPN level in plasma from 3-mo-old infants and umbilical cords was found to be 7 to 10 times higher than in adults. Thus, the high levels of OPN in milk and infant plasma suggest that OPN is important to infants and that ingested milk OPN is likely to induce cytokine production in neonate intestinal immune cells.

Impact of carbohydrate supplementation during endurance training on glycogen storage and performance

AIM

Glucose ingestion may improve exercise endurance, but it apparently also influences the transcription rate of several metabolic genes and it alters muscle metabolism during an acute exercise bout. Therefore, we investigated how chronic training responses are affected by glucose ingestion.

METHODS

In previously untrained males performance and various muscular adaptations were evaluated before and after 8 weeks of supervised endurance training conducted either with (n = 8; CHO group) or without (n = 7; placebo) glucose supplementation.

RESULTS

The two groups achieved similar improvements in maximal oxygen uptake and peak power output during incremental cycling (both parameters elevated by 17% on average) and both groups lost approximately 3 kg of fat mass during the 8 weeks of training. An equal reduction in respiratory exchange ratio (0.02 units) during submaximal exercise was observed in both groups. Beta-hydroxyacyl-CoA-dehydrogenase activity was increased in both groups, however, to a larger extent in the placebo group (45 +/- 11%) than CHO (23 +/- 9%, P < 0.05). GLUT-4 protein expression increased by 74 +/- 14% in the placebo group and 45 +/- 14% in CHO (both P < 0.05), while resting muscle glycogen increased (P < 0.05) to a larger extent in the placebo group (96 +/- 4%) than CHO (33 +/- 2%).

CONCLUSION

These results show that carbohydrate supplementation consumed during exercise training influences various muscular training adaptations, but improvements in cardiorespiratory fitness and reductions in fat mass are not affected.

Postoperative surveillance recommendations for early-stage colon cancer based on results from the clinical outcomes of surgical therapy trial

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Background: Intensive postoperative surveillance is associated with improved survival and recommended for patients with late stage (stage IIB & III) colon cancer. We hypothesized that stage I & IIA colon cancer patients would experience similar benefits. Methods: Secondary analysis of data from the Clinical Outcomes of Surgical Therapy trial was performed by analyzing results according to TNM stage; early (stage I & IIA; 537 patients) and late (stage IIB & III; 254 patients) stage disease. Five-year recurrence rates were higher in patients with late (35.7%) versus early stage disease (9.5%). Early and late stage salvage rates, recurrence patterns and methods of first detection were compared by χ2 test. Results: Salvage rates for early and late stage disease patients with recurrence were the same (35.9% versus 37%, p=0.9 respectively). Median survival following second surgery after recurrence was 35.8 months late stage and 51.2 months for early stage patients respectively. Sites of first recurrence did not significantly differ between late and early stage disease: liver (37.4% vs. 27.2%); lung (29.7% vs.23.6%); intraabdominal (24.2% vs.10.9%); and locoregional (12.1% vs.10.9%). Methods of first detection of recurrence were also not significantly different: CEA (37.4% vs. 29.1%); CT scan (26.4% vs. 23.6%); chest X-ray (12.1% vs. 7.3%); and colonoscopy (8.8% vs. 12.7%), for late versus early stage disease, respectively. Conclusions: Patients with early stage colon cancer have similar sites of recurrence, and receive similar benefit from post-recurrence therapy as later stage patients; implementation of existing surveillance guidelines for early stage patients is appropriate.

No significant financial relationships to disclose.