Disposition of sodium valproate in epileptic patients.

1 Serum levels of valproic acid have been determined at fixed intervals after the administration of single oral and intravenous doses (800 mg) to six epileptic patients receiving chronic treatment with other antiepileptic drugs. 2 Serum levels declined monoexponentially shortly after the intravenous administration. Biological half-lives averaged 9.0 +/- 1.4 h (s.d.). Volumes of distribution were 0.175 +/- 0.025 l/kg. There was a statistically significant negative correlation between volumes of distribution and serum half-lives (P less than 0.005). 3 After oral doses serum levels rose rapidly to peak values within 0.5--2 h. Biological availability was 96 +/- 9%. 4 Comparison with a previous study performed according to the same protocol in healthy volunteers showed significantly increased volumes of distribution and rates of elimination in the patients. Total serum clearance was 85% higher in the patients as compared to the healthy subjects (P less than 0.001). Possible explanations for these findings are discussed.     

Action of tetrodotoxin on spontaneous electrical activity of some smooth muscle preparations

The action of tetrodotoxin (TTX) has been studied in different smooth muscle preparations by recording mechanical and extracellular electrical activities. TTX, although able to abolish nerve-mediated reflex excitation in the small intestine, induced spontaneous firing and segmental contractions in the circular muscle. In both the intestine and the renal pelvis, the effect of TTX was maintained after cholinoceptor and adrenoceptor blockade. The results could be interpreted as evidence that a neurogenic tonic inhibition, possibly not involving cholinergic or adrenergic mechanisms, is operative in the iileum, colon and renal pelvis, and seems to be mainly directed towards the circular musculature of the small intestine.     

A pharmacological analysis of the peristaltic reflex in the isolated colon of the guinea-pig or cat

1. The peristaltic reflex in the colon was elicited by a localized intraluminal stimulus. The contractile response of the longitudinal coat, which consists of two phases, begins before the start of propulsion. Although the contractions of the longitudinal and circular musculature are usually associated, they may be independent of each other. In particular, the longitudinal contraction does not seem to be necessary for propulsion.

2. Both the longitudinal reflex contraction and the segmental responses of the circular muscle to distension, namely a contraction above and a relaxation below the bolus, are abolished by tetrodotoxin and ganglion blocking agents.

3. In the guinea-pig, longitudinal and circular reflex contractions are usually resistant to antimuscarine, antihistamine and antitryptamine drugs but in the cat they are abolished by antimuscarine drugs. In both species, however, atropine and hyoscine can impair propulsion by blocking selectively the descending inhibition. In the cat, it is possible to find doses which abolish the descending inhibition without affecting the contractile responses of the longitudinal and circular muscle.

4. Sympathetic denervation and pretreatment with reserpine do not affect the propulsive activity. The maintenance of the descending inhibition in denervated organs suggests that the inhibitory neurones to the circular muscle are not adrenergic.

5. On the basis of the effects of drugs, the possible nervous mechanism subserving the polarity of propulsion has been examined. Such a mechanism seems to require an inhibitory pathway involving muscarinic receptors at some point.

6. Pelvic nerve stimulation facilitates propulsive activity. The effect of transmural stimulation is different at low and at high frequencies of stimulation. The inhibitory effect of sympathetic stimulation on the reflex responses seems to be due mainly to an action on intrinsic nervous structures.

     

Bacterial contamination of human organ-cultured corneas

PURPOSE: This study was designed to define the risk of contamination of human corneas preserved by the organ-culture method. METHODS: We examined the microbial contaminations in 3,100 corneoscleral rims cultivated in our eye bank. Microbiologic tests were performed in the preservation medium 5 days after the beginning of cornea cultures and in the last day of culture (21.5 +/- 8.1 days), when the corneas were transferred to the deswelling medium. In 1,029 corneas a microbiologic test also was performed 1 day after the beginning of deswelling procedure. RESULTS: We found 206 microbial contaminations (6.65% of total) after 5 days and 17 (0.55%) at the end of the preservation period. The total number of contaminated samples during the cornea culture was 223 corresponding to 7.2% of the samples (95% confidence interval, 6.3-8.1). The 1,029 tests performed during the deswelling step disclosed 26 contaminated cornea cultures despite apparent sterility of the medium (2.5%; 95% confidence interval, 1.5-3.5). CONCLUSIONS: The observation of microbial contaminations in a time close to the transplant (i.e., at the end of the preservation period and in the deswelling step) showed that a fast microbial tests during the deswelling procedure may prevent the grafting of a contaminated cornea. The appearance of bacteria in the deswelling medium despite a negative culture medium suggests that bacteria penetrate the corneal tissues during the culture to be subsequently extruded when the internal fluids move outward.     

Intra-oral bone harvesting: two methods compared using histological and histomorphometric assessments

Aim: This study used morphometric analyses to compare two methods for the intra‐oral harvesting of particulate bone: Mectron Piezosurgery® and the Meta Micross®. Materials and methods: Twenty patients requiring bilateral germectomy of the lower third molars for orthodontic reasons were selected and a sample was harvested from each patient from a standardised donor site (the cortical bone in the area of the retromolar triangle). Ten samples were obtained for each method. The particulate collected were subjected to a histological examination and the samples were analysed considering the following parameters: the mean surface area of fragments, the mean surface area considered vital and the mean surface area considered non‐vital, the mean percentage of area considered vital and the mean percentage of area considered non‐vital, the mean number of normal osteocytes and the mean number of osteocytes with morphological changes identified per unit area (600,000 μm²). The results were analysed, calculating the mean and the corresponding standard deviations, and testing their significance using Student's t‐test, and plotted in graphs. Results: Mectron Piezosurgery® produced significantly larger particles (P<0.05) than the Meta Micross®, with a larger mean surface area considered vital and a significantly larger (P<0.05) surface area considered non‐vital. Mectron Piezosurgery® also produced a smaller mean percentage of area considered vital (64.83%) and a larger mean percentage of area considered non‐vital (35.17%) by comparison with the Meta Micross® (75.34% and 24.66%, respectively). The data also showed that the two methods produce a similar quantity of empty lacunae, and that the Mectron Piezosurgery® produces a larger quantity of osteocytes. Conclusions: The analyses conducted demonstrated that the particulate collected with the Meta Micross® had a smaller mean surface area of the fragments and a smaller surface area of bone considered non‐vital than in the particulate collected using Mectron Piezosurgery®. To cite this article:
Bacci C, Lucchiari N, Valente M, Della Barbera M, Frigo AC, Berengo M. Intra‐oral bone harvesting: two methods compared using histological and histomorphometric assessments. Clin. Oral Impl. Res. 22 , 2011; 600–605.
doi: 10.1111/j.1600‐0501.2010.02022.x