Biocompatibility of new nanostructural materials based on active silicate systems and hydroxyapatite: in vitro and in vivo study

AIM

To evaluate in vitro cytotoxicity and in vivo inflammatory response to new nanostructural materials based on active calcium silicate systems (CS) and hydroxyapatite (HA-CS).

METHODOLOGY

Cytotoxicity of eluates of new nanostructural noncommercial materials CS and HA-CS, and MTA (White MTA, Angelus(®) Soluções Odontológicas, Londrina, Brazil) as a control, were tested using the MTT assay on MRC-5 cells. Eluates of set materials were tested in 100% and 50% concentrations, 24 h, 7 days and 21 days post-elution. The pH values were determined for undiluted eluates of set materials. Polyethylene tubes containing the test materials (CS, HA-CS, MTA) were implanted in subcutaneous tissue of Wistar rats. Histopathological examinations were conducted at 7, 15, 30 and 60 days after the implantation. Data were statistically analyzed using three-way and one-way anova Tukey's post hoc test as well as Kruskall-Wallis test with Dunn's post hoc test at α = 0.05.

RESULTS

All materials significantly reduced cell viability; especially when undiluted eluates were used (P < 0.001). After 24 h elution, cell viability was 10 ± 1.8%, 49.5 ± 4.2% and 61 ± 7.4%, for MTA, and HA-CS, respectively. However, CS and HA-CS were significantly less toxic than the control material MTA (P < 0.05). Cytotoxicity could be at least partially attributed to pH kinetics over time. Dilution of eluates of all tested materials resulted in better cell survival. Histopathological examination indicated similar inflammatory reaction, vascular congestion and connective tissue integrity associated with CS, HA-CS and MTA at each observation period (P > 0.05). The only significant difference was found for capsule thickness, that is thicker capsule was associated with HA-CS compared to MTA at 60 days (P = 0.0039). HA-CS induced moderately thick capsules (median score 3, score range 2-3), whereas MTA resulted in thin capsule formation (median score 2, score range 1-3).

CONCLUSIONS

Evaluation of cytotoxicity and inflammatory response indicated better biocompatibility of CS and HA-CS, in comparison with MTA (White MTA, Angelus(®) Soluções Odontológicas, Londrina, Brazil).

Motor neuron disease and monoclonal gammopathy

In a study to determine the prevalence of monoclonal gammopathy (MG) among patients with motor neuron disease (MND), 6 out of 56 (10.7%) were found to have a monoclonal paraprotein. Of these 6 patients, 4 had an IgG and 2 had an IgA paraprotein. The clinical syndromes consisted of amyotrophic lateral sclerosis in 2 patients, lower motor neuron syndrome with preserved reflexes in at least one limb in 3 patients, and motor neuropathy with multifocal conduction block in 1 patient. The presence of gammopathy appears to correlate with the absence of marked upper motor neuron involvement and with elevated CSF protein concentration. An underlying malignant disorder was ruled out in all 6 patients, and they were considered to have MG of undetermined significance (MGUS). In a control group of 121 age-matched patients with other neuroimmunological disorders, 5 patients (4.13%) had MG. Four of these had gammopathy associated with malignant myeloma, and 1 had MGUS. These results support previous reports of increased prevalence of MGUS in patients with MND and suggest that an autoimmune mechanism may play a role in the disease.

[Histologic manifestations in the skin in alpha-lactoalbumin intradermal tests in patients with chronic urticaria]

Intradermal injection with alpha-lactoalbumine, 2000 PNU/ml was carried out in seven patients (1 male, 6 females, mean age 32.4 years) suffering from milk intolerance. None of the patients had a positive allergen-specific IgE antibodies in the sera (RAST). Skin test was performed on the volar part of the forearms at the same time. The area of skin reaction was estimated and measured within 36 hours on the right arm. Skin biopsy was done with a 4 mm punch after 8 hours from site of antigen injection on the left arm. Various cells infiltrating the site of antigen instillation were present. Leukocytoclastic vasculitis was only found in patients with dual intradermal reaction (immediate and late onset of response; 8 12 hours). These results indicate that local skin reaction to alpha-lactoal-bumine is mediated by diverse immune mechanisms, and that it may be of clinical significance for the diagnosis of cow milk allergy in adults.

Serum and CSF immunological findings in ALS

Serum and CSF immunological findings were analysed in 37 patients with amyotrophic lateral sclerosis (ALS). ALS patients had significantly higher mean values of serum IgG and complement component C4 and significantly lower mean value of total haemolytic titre of complement (THC) compared with normal controls. Incidence of immune complexes (ICs) was significantly higher in sera of ALS patients than in normal controls. There was no significant difference regarding mean serum levels of IgM, IgA, and complement components C3 and Factor B between patients and controls. The blood-brain barrier (BBB) damage was found in 46% of patients. Intrathecal IgG synthesis was detected in six patients (16%). These results support the hypothesis of immune system involvement in ALS.

[Treatment of thyrotoxic ophthalmopathy]

Ophthalmopathy of Graves-Basedow disease appears in 20-50% of patients suffering from thyreotoxicosis. It is usually bilateralophthalmopathy with different degrees of severity. Many noninvasive diagnostical methods are used today. In diagnostic procedure, and especially in therapy, multidisciplinary approaches are compulsory. Although therapeutical effects vary from person to person, only a long follow-up can offer some clinical data about therapeutical success. The authors describe a 39-year-old woman with thyrotoxic bilateral ophthalmopathy. Thyrostatics, such as MMi and PTU, gave no satisfactory therapeutical results. Therefore a therapeutic dose of 131J was administered after which egsophthalmometry (Hertel) revealed regression of thyrotoxic ophthalmopathy, while the ocular signs were more pronounced after the partial thyroidectomy which had had to be carried out because of the existing thyroid functional nodule. The patient responded to corticosteroid therapy by showing a reduction in periorbital oedema, chemosis and hyperemia as well as by lowering the antibody titre against thyroglobulin and disappearing the serum immune complexes.

[Mixed cryoglobulinemia with pepsin agglutinator activity and fragments of IgG in the cryoglobulin]

Transsphenoidal surgery produces changes in the paranasal sinuses and sella that should be familiar to radiologists in view of the frequency of this type of surgery. Some of these changes, such as soft-tissue-density debris in the sinuses, are transient. Fat and other packing material identifiable in the sinuses and sella after surgery is permanent. The procedure is associated with a variety of complications that are readily detectable by computed tomography (CT). These include bleeding, compression of parasellar structures by packing material, cerebrospinal fluid leaks, and pneumocephalus. After a transsphenoidal procedure, with or without follow-up radiation therapy, residual enhancing intrasellar and parasellar lesions may still be identified.

Neonatal rat spinal cord slice preparation: postsynaptic effects of neuropeptides on dorsal horn neurons

In the neonatal rat spinal cord slice preparation responses of the dorsal horn interneurons to iontophoretic or bath application of methionine-enkephalin (ME), substance P (SP) and somatostatin (SS) were qualitatively similar to those obtained in intact spinal cord. Thus, SP powerfully excited almost all neurons tested (15/16), while ME and SS depressed neuronal discharges in 13/14 and 4/6 units respectively. In some dorsal horn neurons the iontophoretic application of ME caused a marked depression of the SP-induced excitation. Angiotensin II (AgII) had no effect on dorsal horn units (n = 8). In the slices perfused with a Ca2+-free, Mg2+-high Krebs solution the extracellularly recorded effects of ME, SP and SS were not significantly modified, suggesting that the peptides were acting directly on postsynaptic sites. The results also indicate that the in vitro rat spinal cord slice preparation can be successfully utilized for further studies on the cellular mechanisms of actions of neuropeptides, particularly in relation to synaptic transmission processes in the dorsal horn.

Cholecystokinin octapeptide excites dorsal horn neurons both in vivo and in vitro

Cholecystokinin octapeptide (CCK-8) applied microiontophoretically causes a moderate to strong excitation of about half of all tested dorsal horn neurons located in laminae I-VII of both the cat intact spinal cord and the rat in vitro spinal cord slice preparation. In the cat intact spinal cord the excitation is not limited to a single population of neurons but is observed in all categories of units recognized in spinal preparations of cats in this area on the basis of their excitability by different kinds of cutaneous afferent input. In the spinal cord slice preparation the excitatory action of CCK-8 persists even when the spinal cord slices are perfused with a Ca2+-free, Mg2+-high Krebs solution. The latter finding indicates that the action of CCK-8 might be a direct one exerted on the postsynaptic sites of dorsal horn units. These results are consistent with the possibility that CCK-8 acts on postsynaptic sites in the dorsal horn of the spinal cord as a neurotransmitter or modulator.

A morphological study of cat dorsal spinocerebellar tract neurons after intracellular injection of horseradish peroxidase

This work represents an attempt to elucidate structural features of electrophysiologically characterized, individual cat dorsal spinocerebellar tract (DSCT) neurons by using intracellular application of horseradish peroxidase (HRP). Intracellular recordings and HRP injections were made in DSCT neurons of the Clarke's column in cat lumbar (L3) spinal cord. The units were identified by antidromic invasion following electrical stimulation of the ipsilateral dorsolateral funiculus at C1. In addition, sensory inputs to the DSCT neurons were determined by natural (adequate) stimuli applied to the hind limb with intact innervation. The morphological analysis is based on data obtained from 19 well-stained electrophysiologically identified neurons located in Clarke's column. Thirteen of these units received excitatory sensory inputs from muscle receptors, two were activated by cutaneous afferents only, and four had a convergent (muscle + cutaneous) input. The DSCT--muscle cells were equivalent to the large Clarke cells (class C of Leowy, '70). Their dendrites were oriented primarily in the rostro--caudal direction (up to 2500 micron) and appeared generally smooth except for some branchlets. In four of these cells, the axon was traced into the lateral funiculus. In light microscopic analysis there was no evidence that axon collaterals arose from these axons during the initial trajectory through the spinal grey matter. The four DSCT--convergent neurons were similar in shape to the DSCT--muscle units although they appeared to have somewhat smaller cell bodies. Of the two DSCT--cutaneous neurons one was found to be of the B type, with the dendritic tree having fewer branches and oriented mainly in the medio--lateral direction. The other cell, however, turned out to be similar in appearance to the C type Clarke neurons.