In Xenopus ependymal cilia drive embryonic CSF circulation and brain development independently of cardiac pulsatile forces

BACKGROUND

Hydrocephalus, the pathological expansion of the cerebrospinal fluid (CSF)-filled cerebral ventricles, is a common, deadly disease. In the adult, cardiac and respiratory forces are the main drivers of CSF flow within the brain ventricular system to remove waste and deliver nutrients. In contrast, the mechanics and functions of CSF circulation in the embryonic brain are poorly understood. This is primarily due to the lack of model systems and imaging technology to study these early time points. Here, we studied embryos of the vertebrate Xenopus with optical coherence tomography (OCT) imaging to investigate in vivo ventricular and neural development during the onset of CSF circulation.

METHODS

Optical coherence tomography (OCT), a cross-sectional imaging modality, was used to study developing Xenopus tadpole brains and to dynamically detect in vivo ventricular morphology and CSF circulation in real-time, at micrometer resolution. The effects of immobilizing cilia and cardiac ablation were investigated.

RESULTS

In Xenopus, using OCT imaging, we demonstrated that ventriculogenesis can be tracked throughout development until the beginning of metamorphosis. We found that during Xenopus embryogenesis, initially, CSF fills the primitive ventricular space and remains static, followed by the initiation of the cilia driven CSF circulation where ependymal cilia create a polarized CSF flow. No pulsatile flow was detected throughout these tailbud and early tadpole stages. As development progressed, despite the emergence of the choroid plexus in Xenopus, cardiac forces did not contribute to the CSF circulation, and ciliary flow remained the driver of the intercompartmental bidirectional flow as well as the near-wall flow. We finally showed that cilia driven flow is crucial for proper rostral development and regulated the spatial neural cell organization.

CONCLUSIONS

Our data support a paradigm in which Xenopus embryonic ventriculogenesis and rostral brain development are critically dependent on ependymal cilia-driven CSF flow currents that are generated independently of cardiac pulsatile forces. Our work suggests that the Xenopus ventricular system forms a complex cilia-driven CSF flow network which regulates neural cell organization. This work will redirect efforts to understand the molecular regulators of embryonic CSF flow by focusing attention on motile cilia rather than other forces relevant only to the adult.

Endoscopic versus transaxillary thoracic sympathectomy for primary axillary and palmar hyperhidrosis and/or facial blushing: 5-year-experience

Thoracic sympathectomy is effective in the permanent cure of primary axillary and palmar hyperhidrosis and facial blushing, which can be so troublesome for patients that their social and professional relations can be affected. Between October 1988 and April 1994, a total of 50 thoracic sympathectomies (10 surgical and 40 endoscopic) were performed on 5 and 23 patients, respectively. The operations were performed unilaterally, followed by the contralateral intervention after a period of 6-8 weeks. The thoracic ganglia T2-T5 were resected for hyperhidrosis. If the patient suffered from blushing, the lower 1/3 of the stellate ganglion was also resected. Postoperatively, all the operated limbs were warm and dry. In the group of patients who were operated bilaterally, only one had persistent facial blushing. The efficacy for blushing in this series was therefore 93.3%. The late relapse rate of sympathetic activity was 14.3%. Compensatory sweating was seen in 67%, gustatory sweating in 37.5% and phantom sweating in 29% of the patients. None of them considered these side effects to be troublesome. Although there is no difference between transaxillary thoracic sympathectomy and the endoscopic intervention in terms of efficacy, the latter is associated with less postoperative pain, shorter hospital stay and a rapid recovery. The thoracic sympathectomy is the treatment of choice for primary hyperhidrosis and excessive facial blushing.

The distribution of peripheral vascular disease in a Dutch Caucasian population: comparison of type II diabetic and non-diabetic subjects

OBJECTIVES

To study the distribution of peripheral vascular disease and the relationship to diabetes.

DESIGN

Prospective population based study of Dutch caucasian inhabitants.

METHODS

From a total of 10,500 subjects aged between 50 and 75 years, 2484 Caucasian inhabitants were screened with respect to their glucose tolerance. Subjects using oral antidiabetic agents or insulin were classified directly as having diabetes mellitus. The other participants were screened using two oral glucose tolerance tests and classified using WHO criteria. A group of 173 people with diabetes and a representative age/sex stratified sample of 288 non-diabetic subjects were seen in the vascular laboratory. Carotid artery disease was investigated with Duplex scanning, arm and leg artery obstructions with real time frequency analysis of continuous wave Doppler signals and indirect blood pressure measurements.

RESULTS

Comparing diabetic with non-diabetic subjects, we found significantly more obstructions of the carotid arteries (8.7 vs 2.8%), arm arteries (2.3 vs 0%), as well as leg arteries (31.8 vs. 18.4%). The same holds if only the crural artery obstructions were compared (23.7 vs 16.0%). Two of the four diabetic subjects with arm artery obstructions had retrograde vertebral flow, three of them had carotid artery obstructions as well, and three also had leg artery obstructions. More than half of the subjects with a carotid artery obstruction, also had leg artery obstructions.

CONCLUSIONS

Peripheral vascular disease is common in diabetes, but most are asymptomatic.

[Ascending phlebothrombosis]

Ascending phlebothrombosis of the lower extremities can have serious consequences if not identified at an early stage. In the Academic Hospital of the Free University, Amsterdam, 18 patients with this disease were seen in the period 1980-1991. Treatment should be aimed at preventing progression of the disease to the deep venous system. This may necessitate ligation and dissection of the V. saphena magna in the groin. Usually conservative treatment will do, provided regular follow-up is performed to see whether progression has taken place to the hiatus saphenus or the popliteal fossa. As the disease has usually progressed further than the clinical signs indicate, duplex scanning should be used in case of doubt. Progression to the deep system should immediately be treated surgically.

Two sisters with coeliac disease and jejunal cancer: just a coincidence?

Two sisters with asymptomatic coeliac disease are described; they both developed a primary jejunal cancer at the same age. While screening the family, a third sister was found to have coeliac disease, but without detectable cancer in the small intestine or stomach. These findings suggest an increased susceptibility in this family for carcinoma developing secondary to asymptomatic coeliac disease. We conclude that the finding in a patient of the combination of coeliac disease and malignancy in the digestive tract is sufficient reason to investigate the first-degree relatives with regard to the presence of coeliac disease and a secondary carcinoma.