Biomedical subjects

Johan W van Neck

Publications and source records attributed to Johan W van Neck.

7 recordsLinked to original sources

PubMed2006

Recovery of neurophysiological features with time after rat sciatic nerve repair: a magneto-neurographic study.

Experimental assessment of peripheral nerve regeneration in rats by electrophysiology is controversial due to low reproducibility of electrophysiological indicators and diminished quantitative evaluation in conventional experimental set-ups. Magnetoneurography (MNG) counteracts these drawbacks by magnetically recording electrophysiological signals ex vivo, thereby providing accurate and quantitative data. In 50 rats, sciatic nerve transection was followed by direct repair. MNG outcome parameters, footprints [static toe spread factor (TSF); function] and muscle weight (MW) were studied for their recovery pattern from 2 to 24 weeks. By using MNG, we showed that the regeneration process still continues when functional recovery (static TSF) becomes stagnant. With regression analysis, MNG parameters amplitude, amplitude area and conduction velocity (CV) demonstrated moderate significant correlation with MW, whereas CV was not significantly associated with static TSF. No significant association exists between MW and static TSF. A Kaplan-Meier survival curve revealed that autotomy/contracture of rat hind paws was not related to decreased MNG outcome values. In conclusion, this study highlights and discusses the dissimilarities between direct (MNG) and indirect (static TSF and MW) assessment techniques of the regeneration process. We emphasise the significance of MNG as a direct derivative of axon regeneration in experimental rat studies. Additionally, we stress the must for right-left ratios, as neurophysiological indicators vary with age, and we confute possible bias in footprint analysis caused by exclusion of autotomy/contracture animals.

Age Factors↗

PubMed2005

Ultrasound imaging of the rabbit peroneal nerve.

Ultrasound imaging of peripheral nerves is increasingly used in the clinic for a wide range of applications. Although yet unapplied for experimental neuroscience, it also has potential value in this research area. This study explores the feasibility, possibilities and limitations of this technique in rabbits, with special focus on peripheral nerve regeneration after trauma. The peroneal nerve of 25 New Zealand White rabbits was imaged at varying time intervals after a crush lesion. The ultrasonic appearance of the nerve was determined, and recordings were validated with in vivo anatomy. Nerve swelling at the lesion site was estimated from ultrasound images and compared with anatomical parameters. The peroneal nerve could reliably be identified in all animals, and its course and anatomical variations agreed perfectly with anatomy. Nerve diameters from ultrasound were related to in vivo diameters (p < 0.001, R(2) = 77%), although the prediction interval was rather wide. Nerve thickenings could be visualized and preliminary results indicate that ultrasound can differentiate between neuroma formation and external nerve thickening. The value of the technique for experimental neuroscience is discussed. We conclude that ultrasound imaging of the rabbit peroneal nerve is feasible and that it is a promising tool for different research areas within the field of experimental neuroscience.

Animals↗

PubMed2004

Static footprint analysis: a time-saving functional evaluation of nerve repair in rats.

Walking track analysis is a widely accepted technique for functional evaluation after sciatic nerve repair in rats, but it is labour-intensive. In 2000, Bervar described a time-saving digitised static footprint analysis. In that study there were good correlations between the traditional sciatic function index (SFI) and the newly-developed static sciatic index (SSI) and static toe spread factor (TSF), respectively. Despite promising results, static footprint analysis is still not widely used. The present study was designed to validate it. After transection of the sciatic nerve, end-to-end repair was assessed using video recorded dynamic and static footprints in 45 Wistar rats. We found an even better correlation between the SFI and both the SSI and the static TSF. In conclusion, static footprint analysis is a time-saving and easy technique for accurate functional assessment of peripheral nerve regeneration in rats.

Animals↗

PubMed2004

Reduction of neural adhesions by biodegradable autocrosslinked hyaluronic acid gel after injury of peripheral nerves: an experimental study.

OBJECT: Adhesion formation is a serious problem in peripheral nerve surgery, frequently causing dysfunction and pain. The authors aimed to develop an objective biomechanical method of quantifying nerve adhesions and to use this technique for the evaluation of the efficacy of an autocrosslinked hyaluronic acid (HA) gel as an antiadhesion therapy. METHODS: Thirty-three female Wistar rats underwent dissection, crush injury, or transection plus repair of the sciatic nerve. The nerves were or were not treated with the HA gel. Six weeks after surgery, the adhesions formed were assessed by measuring the peak force required to break the adhesions over a standardized area. Results of biomechanical measurements demonstrated that the peak force significantly increased as the severity of the injury increased. After using the HA gel to treat the nerve, the peak force was significantly reduced in rats with any of the three types of injuries; peak force decreased by 26% in the animals in the dissection group, 29% in the crush injury group, and 38% in the transection and repair group, compared with the untreated animals. CONCLUSIONS: The biomechanical method described is an objective, quantitative technique for the assessment of nerve adherence to surrounding tissue. It will be a valuable tool in future studies on antiadhesion therapies. Furthermore, HA gel significantly reduces nerve adhesions after different types of nerve injuries.

Adjuvants, Immunologic↗

PubMed2003

Magnetoneurography: recording biomagnetic fields for quantitative evaluation of isolated rat sciatic nerves.

Magnetoneurography (MNG) is a technique to record the biomagnetic action fields of peripheral nerves. The benefits of MNG in contrast to electroneurography include the decreased signal disturbance caused by surrounding biological tissues and the use of a calibration pulse, both of which contribute to high reproducibility. MNG has proven to be a valuable tool to quantitate peripheral nerve regeneration in rabbits. However, the most commonly used model to study the peripheral nervous system is the rat sciatic nerve. Until now, the small size of the nerve impeded accurate MNG measurements in rat. This report describes a custom made recording chamber that allows accurate control of conduction distances and temperature and enables adequate MNG measurements of isolated sciatic nerves of Wistar rats. We applied biphasic stimulation with optimized grounding to reduce the stimulus artefact. A high reproducibility of signals was demonstrated. 'Ex vivo' nerve viability was assured for at least 2 h after dissection. In conclusion, MNG is a powerful tool to quantitatively evaluate the function of rat sciatic nerves and will be used for the early assessment of nerve regeneration.

Animals↗

PubMed2003

Difficulties in conducting a prospective outcome study.

The success of an outcome study depends largely on the number of recruited patients, the loss of followup, and the response rate to postal questionnaires. In this article, different strategies were proposed to increase the aforementioned items. Most presented strategies were developed because of failure of measures used earlier. In the authors' study concerning hand surgery, this resulted in missed inclusions and loss of followup. It is hoped that by reading and using the strategies discussed, future researchers will start at the end of the learning curve and will shed a bright light on the obscurity of recovery after hand injury.

Hand Injuries↗

PubMed2002

High-protein induced renal enlargement is growth hormone independent.

BACKGROUND: Growth hormone (GH) and insulin-like growth factors (IGFs) have been postulated as pathogenic factors in several forms of renal growth, including that induced by high-protein (HP) diets. Compensatory renal growth (CRG) following renal uninephrectomy is strictly GH dependent, while the exact role of GH as a regulating factor in HP induced renal growth has not been fully clarified. METHODS: To elucidate a possible direct role for GH in HP-induced renal growth, we examined the effect of a newly developed specific GH-receptor (GHR) antagonist (B2036-PEG) on renal growth and renal GH/IGF-system expression in HP-fed mice. RESULTS: Mice fed a HP diet (45% protein) for one week demonstrated renal hypertrophy and increased renal IGF-I. GH receptor antagonist (GHRA) treatment neither modified renal IGF-I nor abolished the renal hypertrophy. In contrast, however, GHRA administration did modify renal mRNA expression of many members of the GH and IGF systems. CONCLUSIONS: The major new finding is that HP-induced renal growth in adult mice is GH independent.

Animals↗