Effects of GABA on acutely isolated neurons from the gustatory zone of the rat nucleus of the solitary tract

Responses of acutely isolated neurons from the rostral nucleus of the solitary tract (rNST) to GABA receptor agonists and antagonists were investigated using whole-cell recording in current clamp mode. The isolated neurons retain their morphology and can be divided into multipolar, elongate and ovoid cell types. Most rNST neurons (97%), including all three cell types, respond to GABA with membrane hyperpolarization and a reduction in input resistance. The GABA(A) receptor agonist muscimol reduces neuronal input resistance in a concentration-dependent manner, whereas the GABA(B) receptor agonist baclofen had no effect on any of the neurons tested. The GABA and muscimol reversal potentials were both found to be -75 mV Both the GABA competitive antagonist picrotoxin and the GABA(A) receptor antagonist bicuculline block the effect of GABA in a concentration-dependent manner. These results suggest that GABA activates all neurons in the rNST and that inhibitory synaptic activity is important in brainstem processing of gustatory and somatosensory information.      

Replacement of receptor cells in the hamster vomeronasal epithelium after nerve transection

Chemoreceptor cells in the vomeronasal and olfactory epithelium are replaced following experimentally induced degeneration. This study analyzes quantitatively the time course and degree of vomeronasal receptor cell replacement. Unilateral transection of the vomeronasal nerves in adult hamster was used to induce a retrograde degeneration of receptor cells in the vomeronasal organ. Histological measurement of both number of receptor cells and epithelial thickness were made for recovery times from 0 to 60 days. After nerve transection, there was a gradual degeneration of receptor cells, the number decreasing to 50% of control by day 2 and 16% by day 6. During days 7-15 maximum receptor cell replacement was observed. Cell number increased rapidly and reached a peak on day 15. At recovery times of 40-60 days, cell number returned to the control level. Epithelial thickness, however, decreased to 60-70% during the degeneration period (days 4-6) and did not return to control levels. After 40-60 days epithelial thickness remained at 70% of control. These results demonstrate that vomeronasal receptor cells are replaced following degeneration, but epithelial thickness does not return to control levels. These findings suggest that the number of replacement cells is not limited by the reduced thickness of the epithelium, and that recovery mechanisms may function to restore an optimum number of receptor cells.      

Evaluation of the time course of neurotransmitter release from the measured PSC and MPSC

A method for obtaining delay histograms for the time course of neurotransmitter release is presented. The delay histogram is derived from the measured psc (or the sum of several psc's) and the mpsc (obtained experimentally or otherwise) by means of a simple, quick, mathematical procedure. The procedure may be automated for the greater part. No approximation of the mpsc shape is performed, and the method is applicable to all quantal contents. For low and medium quantal contents, the delay histograms obtained by the method are compared to those obtained by direct analysis. A reasonable agreement is achieved. An experiment of high quantal content, for which direct analysis is impossible, is then analysed using the new method. Difficulties which may arise when applying the procedure and methods to overcome them are discussed at length. Other methods are set forth in the Discussion.     

Prospective study on the influence of radiochemotherapy on pituitary function in children with acute leukaemia and NHL.

To assess effects of chemo- and radiotherapy on the endocrine system 31 children with acute leukaemia and NHL (3 AML, 24 ALL, 4 NHL) were investigated. Children were treated according to modified BFM protocols. 25 patients were before, 5 during and one after puberty (2 to 16 y.). Before treatment, during induction therapy, during cranial irradiation, 4-6 weeks later and during maintenance therapy the following hormone values were estimated: TSH and prolactin basal and 30 min. after TRH (5 micrograms/kg i.v.), LH and FSH basal. Final investigations included total T4 and T3. In conclusion, chemo- und radiotherapy lead to transient elevations of TSH and prolactin in a few patients, but without proof for permanent disorders. Due to the fact all 3 patients with hyperprolactinaemia showed high prolactin levels (700 to 770 mU/l) already before treatment it is unlikely therapy was the main cause of these observed alterations. Although basal LH and FSH values were in normal ranges for age the increasing values after cranial irradiation in prepubertal children may reflect a possible initiation of early maturation, reported by others. Furthermore a retrospective growth study was performed in children treated with 2 different protocols. Protocol LSA2L2 used in the past before 1981 resulted in a permanent reduction of the height. In contrast, the mean SDS for height in children treated with protocol VII declined only during the intensive period of treatment. A catch-up growth occured already during maintenance therapy. Prophylactic cranial irradiation with 18 Gy in our patients under protocol LSA2L2 did not affect growth during the first 5 years after diagnosis.     

Arthrosonography--a modern method for morphologic and functional joint evaluation in hemophilia]

The arthrosonography is a new depicting procedure for detection of destructing joint processes in haemophilia. A direct evaluation of the cartilage, of the border between cartilage and bone, of the synovial membrane with proliferative processes as well as the differentiation between soft-tissue bleeding and haemarthros are possible. An essential advantage is given by a combined morphological and functional joint evaluation. The diagnosis of joint instabilities can be recognized easier by sonography than by X-ray. Clinical findings are completed in an excellent manner and lesions of bone and cartilage are detected earlier by arthrosonography.