Developmental changes of the mitochondria in the murine anteroventral cochlear nucleus

Mitochondria are key organelles to provide ATP for synaptic transmission. This study aims to unravel the structural adaptation of mitochondria to an increase in presynaptic energy demand and upon the functional impairment of the auditory system. We use the anteroventral cochlear nucleus (AVCN) of wild-type and congenital deaf mice before and after hearing onset as a model system for presynaptic states of lower and higher energy demands. We combine focused ion beam scanning electron microscopy and electron tomography to investigate mitochondrial morphology. We found a larger volume of synaptic boutons and mitochondria after hearing onset with a higher crista membrane density. In deaf animals lacking otoferlin, we observed a shallow increase of mitochondrial volumes toward adulthood in endbulbs, while in wild-type animals mitochondria further enlarged. We propose that in the AVCN, presynaptic mitochondria undergo major structural changes likely to serve higher energy demands upon the onset of hearing and further maturation.

Ultrastructural maturation of the endbulb of Held active zones comparing wild-type and otoferlin-deficient mice

Endbulbs of Held are located in the anteroventral cochlear nucleus and present the first central synapses of the auditory pathway. During development, endbulbs mature functionally to enable rapid and powerful synaptic transmission with high temporal precision. This process is accompanied by morphological changes of endbulb terminals. Loss of the hair cell-specific protein otoferlin (Otof) abolishes neurotransmission in the cochlea and results in the smaller endbulb of Held terminals. Thus, peripheral hearing impairment likely also leads to alterations in the morphological synaptic vesicle (SV) pool size at individual endbulb of Held active zones (AZs). Here, we investigated endbulb AZs in pre-hearing, young, and adult wild-type and Otof^−/− mice. During maturation, SV numbers at endbulb AZs increased in wild-type mice but were found to be reduced in Otof^−/− mice. The SV population at a distance of 0–15 nm was most strongly affected. Finally, overall SV diameters decreased in Otof^−/− animals during maturation.

•

Maturation of wt endbulb of Held active zones leads to more synaptic vesicles

•

At endbulbs of otoferlin knockout mice, synaptic vesicles decline with age

•

Mainly two distinct synaptic vesicle populations are affected

•

Synaptic vesicles sizes are reduced in six-month-old otoferlin knockout animals

Comparative investigations on the efficacy of articaine 4% (epinephrine 1:200,000) and articaine 2% (epinephrine 1:200,000) in local infiltration anaesthesia in dentistry--a randomised double-blind study

A randomised double-blind study investigated 155 patients with tooth extractions in the mandibular and maxillary jaws for a loss of anaesthetic potency when reducing the concentration of the active in articaine solutions. Tests were performed on the preparations of articaine 4% with a 1:200,000 addition of epinephrine (Ultracain D-S) and articaine 2% with a 1:200,000 addition of epinephrine (Ultracain 2%-Suprarenin). Local infiltration anaesthesia was the chosen method of anaesthesia. The most noticeable difference observed between the two injection solutions concerned the duration of anaesthesia, which was significantly shortened under the low-dose solution. The 4% articaine solution did not prove superior in local anaesthetic effect. Articaine 2% with epinephrine 1:200,000, therefore, can be considered a suitable local anaesthetic for tooth extractions.

Diagnosis of pancreatic adenocarcinoma by polymerase chain reaction from pancreatic secretions

As mutations at codon 12 of the Ki-ras oncogene have been shown to occur in 90% of pancreatic adenocarcinomas, a novel strategy for the detection of these mutations in pancreatic secretions obtained at routine endoscopies was developed. Ki-ras DNA was amplified and screened for the presence of mutations at codon 12 with a combination of different rapid, non-radioactive molecular biology techniques. Examination of DNA from cell lines and paraffin-embedded tumour samples was used to establish and test the strategy employed. Pancreatic secretions from 27 patients were examined for the presence of Ki-ras mutations. Mutations at codon 12 were detected in 16/16 secretions from patients with histologically confirmed carcinoma and from one patient with carcinoma of the bile duct. In six patients a mutation identical to the one found in the pancreatic secretions was also demonstrated in paraffin-embedded fine-needle biopsy or surgical samples. Of the remaining ten patients (who had pancreatitis or cholelithiasis) mutations were not found in nine. Ki-ras codon 12 mutation was identified in one of these patients however, and mucous cell hyperplasia of pancreatic ducts was found upon histological examination. These findings establish Ki-ras polymerase chain reaction from pancreatic secretions as a valuable new diagnostic procedure for the demonstration of malignant cells, possibly at an early stage of the disease.

[Digital radiography. Experiences with the SP system]

Digital radiography which would have to replace conventional radiography with equal or improved quality is the still missing link in the development of a fully digital imaging department of the future. Various attempts have been made to close this gap. This article describes the SP system, a large area detecting digital imaging system, originally designed by Fuji. Its components are the imaging plate, coated with a stimulable phosphor (SP), which is used like a conventional film-screen cassette, a laser-based image reader, the image processor and a laser-based image printer. After a six months' test in hospital routine, the advantages, shortcomings and possible improvements are discussed.

[Myelomalacia following vertebral angiography with a femoral catheter (author's transl)]

Cerebral angiography with femoral catheters in two patients was followed by an incomplete cervical transverse myelitis. The complications were thought to be due to high contrast concentration in the cervical spinal vessels because of hypoplasia of one vertebral artery, and to contrast injection into the thyro-cervical trunk.