Oral candidiasis following steroid therapy for oral lichen planus.

OBJECTIVES: The purpose of this multicentre study was to determine the incidence of oral candidiasis in patients treated with topical steroids for oral lichen planus (OLP) and to determine whether the application of a concurrent antifungal therapy prevented the development of an oral candidiasis in these patients. MATERIALS AND METHODS: Records of 315 patients with OLP seen at four Oral Medicine practices treated for at least 2 weeks with steroids with and without the use of an antifungal regimen were retrospectively reviewed. RESULTS: The overall incidence of oral fungal infection in those treated with steroid therapy for OLP was 13.6%. There was no statistically significant difference in the rate of oral candidiasis development in those treated with an antifungal regimen vs those not treated prophylactically (14.3% vs 12.6%) (P = 0.68). CONCLUSIONS: Despite the use of various regimens, none of the preventive antifungal strategies used in this study resulted in a significant difference in the rate of development of an oral candidiasis in patients with OLP treated with steroids.

Botulinum neurotoxin A blocks synaptic vesicle exocytosis but not endocytosis at the nerve terminal.

The supply of synaptic vesicles in the nerve terminal is maintained by a temporally linked balance of exo- and endocytosis. Tetanus and botulinum neurotoxins block neurotransmitter release by the enzymatic cleavage of proteins identified as critical for synaptic vesicle exocytosis. We show here that botulinum neurotoxin A is unique in that the toxin-induced block in exocytosis does not arrest vesicle membrane endocytosis. In the murine spinal cord, cell cultures exposed to botulinum neurotoxin A, neither K(+)-evoked neurotransmitter release nor synaptic currents can be detected, twice the ordinary number of synaptic vesicles are docked at the synaptic active zone, and its protein substrate is cleaved, which is similar to observations with tetanus and other botulinal neurotoxins. In marked contrast, K(+) depolarization, in the presence of Ca(2+), triggers the endocytosis of the vesicle membrane in botulinum neurotoxin A-blocked cultures as evidenced by FM1-43 staining of synaptic terminals and uptake of HRP into synaptic vesicles. These experiments are the first demonstration that botulinum neurotoxin A uncouples vesicle exo- from endocytosis, and provide evidence that Ca(2+) is required for synaptic vesicle membrane retrieval.

Early dendrite development in spinal cord cell cultures: a quantitative study.

Neurons in dissociated cell culture provide a favorable system for the quantitative analysis of structural changes and the examination of structure-function relationships during development. Fragment C of tetanus toxin was used to label neurons in murine spinal cord cell cultures and dendrite outgrowth was monitored by a number of measures. The dissociated neurons increased in morphologic complexity from approximate spheres to highly branched structures during the first week in culture. Much of the structural complexity of the dendrite arbor, as quantified by fractal dimension, was established within 48 hr after plating, i.e., prior to the development of interneuronal contacts. During the first few days in culture, dendrite branching complexity increased more rapidly than dendrite size, whereas after 4 days, fractal dimension remained relatively constant while dendrites continued to grow. Fractal analysis has provided data which suggest that the early development of dendrite branching complexity is determined intrinsically. Fractal dimension, as an effective index of morphologic complexity, should be a useful tool for the further study of extrinsic signals which might modify the generation or stabilization of dendrite form.

Vasoactive intestinal peptide: a neurotrophic releasing agent and an astroglial mitogen.

Vasoactive intestinal peptide (VIP) increases neuronal survival in dissociated spinal cord cultures during a critical period of development. In the present study, two mechanisms contributing to this action of VIP have been observed: 1) VIP was shown to be a secretagogue for neuron survival-promoting activity; and 2) VIP was found to be an astroglial mitogen. A high molecular weight substance (greater than 30 kDa), which increased neuronal survival in tetrodotoxin (TTX)-treated spinal cord cultures, was detected in the medium from nonneuronal cells incubated for 1 hr with 0.1 nM VIP. In addition, 3H-thymidine autoradiography and glial fibrillary acid protein (GFAP) immunocytochemistry were used to show that a 5 day treatment with (VIP) increased astroglial mitosis. This effect was specific for astroglia, as silver grain-positive cells not exhibiting GFAP immunoreactivity did not increase in number after VIP treatment. The dual action of VIP may regulate glial-derived trophic substances that are important for neuronal survival during the course of development.

Developmental and neurochemical specificity of neuronal deficits produced by electrical impulse blockade in dissociated spinal cord cultures.

Blockade of spontaneous electrical activity in dissociated fetal spinal cord cultures produced neuronal deficits as measured by biochemical and morphological techniques. Spinal cord cultures exhibited an age-dependent vulnerability to impulse blockade with tetrodotoxin (TTX) or xylocaine. Neuronal cell counts, [125I]tetanus toxin fixation and [125I]scorpion toxin binding indicated that TTX application produced neuronal deficits during the second or third week in culture. Application of TTX during the first or fourth week did not produce a difference in tetanus toxin fixation from controls. Radioautography of [125I]tetanus toxin revealed no obvious change in the label distribution after TTX treatment. Suppression of electrical activity during the first 6 days in culture had no effect on choline acetyltransferase (CAT) activity and no apparent effect on the appearance of the cultures. Application of TTX during the seventh day in culture decreased CAT activity to 68% of control. Chronic electrical blockade produced a progressively greater loss of CAT activity through 21 days in culture. GABAergic neurons, as indicated by high-affinity GABA uptake, glutamic acid decarboxylase activity and [3H]GABA radioautography, were not affected by electrical blockade. These data indicate that there is developmental and neurochemical specificity in the neuronal death produced by blocking spontaneous electrical activity in dissociated spinal cord cultures.

Synaptic interactions between mammalian central neurons in cell culture. III. Morphophysiological correlates of quantal synaptic transmission.

The statistical properties of excitatory synaptic transmission between neurons in cell cultures of fetal mouse spinal cord were studied and the anatomical extent of these connections demonstrated by horseradish peroxidase (HRP) injection of the presynaptic cell. In conjunction with previous experiments (7), we have correlated the number of boutons involved in a given synaptic connection with the physiologically determined number of release elements. The number of boutons is somewhat greater than the number of release elements, and our results are supportive of the conclusion of others (1, 2) that the physiologically defined release element corresponds to the bouton. We interpret this to suggest that a rate-limiting mechanism may operate at the level of the bouton to allow release of no more than one quantal unit of transmitter with each presynaptic action potential.

Glutamate decarboxylase immunoreactivity and gamma-[3H] aminobutyric acid accumulation within the same neurons in dissociated cell cultures of cerebral cortex.

In order to evaluate the reliability of high affinity [3H]GABA accumulation as a marker for GABAergic neurons, murine cerebral cortical neurons were studied in dissociated cell culture. Cultures which had been incubated in [3H]GABA were stained immunohistochemically for the GABA-synthesizing enzyme, glutamate decarboxylase, fixed with paraformaldehyde, and subsequently processed for radioautography. In mature cultures, there was an 84 to 94% correlation between the presence of the enzyme and [3H]GABA uptake within the same cortical neurons. These data provide direct evidence that those neurons which synthesize GABA are the same neurons which are labeled by high affinity [3H]GABA uptake.