Root resorption and its association with alterations in physical properties, mineral contents and resorption craters in human premolars following application of light and heavy controlled orthodontic forces.

OBJECTIVES: To study the effect of different orthodontic force levels on cementum, investigating from the point of view of its physical properties, alterations in the mineral components, type and location of the resorption craters and the exploration in 3D of space. DESIGN: In vivo human premolars subjected to heavy and light forces were employed for this study. After a period of movement they were analyzed for hardness and elasticity. Also, the mineral composition measuring Ca, P and F of the cementum root surface was investigated. A new method for volumetric analysis of resorption craters was developed. RESULTS: There were no significant differences for hardness and elastic modulus between the light and heavy force groups and no significant effects for different tooth positions. Significant inter-individual variation in the Ca, P and F concentrations was noted. Force-related data showed that mean volume of the resorption crater in light-force group was 3.49-fold greater than the control group, and the heavy-force group 11.59-fold more than control group. The heavy force group had 3.31-fold greater total resorption volume then light force group. Buccal cervical and lingual apical regions demonstrated significantly more resorption craters than the other regions. The 2D measurements were strongly correlated to 3D measurements. CONCLUSION: The application of light and heavy forces did not show any statistically significant differences in hardness and elastic modulus when compared with untreated teeth. The inconsistent increase or decrease of Ca, P and F contents between control and experimental teeth at sites of compression and tension were difficult to explain. There was more resorption by volume in the heavy force group as compared with the light group and controls. Our data also suggested that the high-pressure zones might be more susceptible to resorption after 28 days of force application.

Efficacy of external fixation following nasal manipulation under local anaesthesia.

Nasal fractures are one of the commonest reasons for patients being referred to ENT departments, but few studies have been published about the management of this condition. In particular, the efficacy of external splintage following manipulation has not been assessed. This was a prospective randomized study, which examined the results of manipulation under local anaesthetic and the benefit to be gained from external fixation with Plaster of Paris (POP) following this procedure. Accurate measurements of the degree of deviation of the nose pre- and post-manipulation were obtained using a camera mounted on a specially designed frame. Thirty-three out of 241 consecutive patients seen at a research clinic over the course of 12 months were included in the study. The mean deviation of the nasal bridge at presentation was 4.12 mm. Manipulation under local anaesthetic significantly improved the degree of deviation (mean 2.47 mm, P = 0.0011, 90% CI, 1-2 mm). Randomization of the patients, following manipulation, into POP/none-POP groups showed that external splintage of the nose appeared to be of little practical benefit.

A phase II study of cisplatinum versus cisplatinum + nifedipine in end-stage carcinoma of the head and neck.

Forty patients with end-stage carcinoma of the head and neck were admitted to a randomized double blind trial with cisplatinum in one arm and cisplatinum + nifedipine in the other. Nifedipine, a calcium channel blocking drug, inhibits the effect of acquired multidrug resistance in animal models. In the present study the addition of this agent had no effect on either response rate or survival in end-stage carcinoma of the head and neck. It is concluded that adding nifedipine to cisplatinum serves no useful purpose in the treatment of end-stage carcinoma of the head and neck.

Nasal sensation of airflow following blockade of the nasal trigeminal afferents.

A matched-pair parallel, group trial was carried out on 2 groups of 13 subjects (26 subjects in total), using 2% aqueous lignocaine to anaesthetize both the nasal vestibule and the nasal mucous membrane. Both groups had lignocaine infiltrated into the nasal vestibule and lignocaine applied topically to the nasal mucous membrane. The groups differed in the order in which the medication was given, one group having the infiltration first and the other group the topical application first. Local anaesthesia of the nasal vestibule caused a marked decrease in the nasal sensation of airflow (P less than 0.05) with no accompanying change in nasal resistance to airflow. Topical anaesthesia of the nasal mucous membrane had no effect on either nasal sensation of airflow or nasal resistance. The study demonstrates that the nasal vestibule is the dominant area for sensing nasal airflow. The nasal cavum (the major part of the nasal cavities that is lined by respiratory mucosa) appears to be unimportant as regards the sensation of nasal airflow. The clinical significance of the study is discussed with reference to other work, in this field.

The effect of local anaesthesia of the nasal vestibule on nasal sensation of airflow and nasal resistance.

The effect of local anaesthesia of the nasal vestibule on nasal sensation of airflow and nasal resistance was assessed in 15 subjects. A single blind parallel group trial was undertaken in 30 subjects, with lignocaine as the active drug, and normal saline as the placebo. Fifteen subjects were included in each group. Both agents were infiltrated bilaterally into the floor of the nasal vestibule on each side via the sublabial route. Local anaesthesia of the nasal vestibule by infiltrating lignocaine produced a sensation of nasal obstruction in 9 out of 15 subjects (P less than 0.02). The infiltration of normal saline had no such effect. The difference between the effect of the 2 agents on nasal airflow sensation was significant (P less than 0.05). Neither injection had any significant effect on nasal resistance to airflow as assessed by active anterior rhinomanometry.

The effects of camphor, eucalyptus and menthol vapour on nasal resistance to airflow and nasal sensation.

The effects of five minutes exposure to camphor, eucalyptus or menthol vapour on nasal resistance to airflow and nasal sensation of airflow were compared with the effects of exercise on the nose. Inhalation of camphor, eucalyptus or menthol had no effect on nasal resistance to airflow but the majority of subjects reported a cold sensation in the nose with the sensation of improved airflow. Exercise caused a decrease in nasal resistance but did not induce any nasal sensation of cold or improved airflow. The results indicate that camphor, eucalyptus and menthol stimulate cold receptors in the nose. The clinical significance of nasal sensation of airflow is discussed.

Synthesis and biological properties of 2'-deoxy-5-vinyluridine and 2'deoxy-5-vinylcytidine.

Rapid and efficient syntheses for the preparation of 2'-deoxy-5-vinyluridine and 2'-deoxy-5-vinylcytidine are described starting from nucleoside precursors. Contrary to some previous reports, 2-deoxy-5-vinyluridine has be found to be quite stable under normal laboratory conditions but when tested in animals shows neither toxicity nor anti-leukemic (L1210 cells) or anti-parasitic (Plasmodium berghei) activity. 2'-Deoxy-5-vinylcytidine appears to polymerise readily. It is much less toxic to cell cultures than 2'-deoxy-5'vinyluridine but is almost as active against herpes virus replication (ID50:0.2 microgram/ml) for both type 1 and type 2 herpes virus (selectivity index:225).

The synthesis and properties of some 5-substituted uracil derivatives.

The problems encountered in the synthesis of 5-vinyl-2'-deoxyuridine are outlined and the synthesis of 5-bromoethynyl-2'-deoxyuridine described. E-5-(2-Bromovinyl)-2'-deoxyuridine is the most potent and specific agent against some herpes viruses yet discovered; we have now synthesised the Z-isomer and this appears to be essentially biologically inert.

Plasmapheresis-induced hemodilution and its effects on serum constituents.

Samples were obtained from 23 plasmapheresis donors before, during, and after double plasmapheresis. Seventeen chemical analyses were performed on these specimens and the results were subjected to statistical analysis. Representative samples can be obtained from plasmapheresis donors before the procedure has begun, immediately after the first unit of whole blood has been removed, or 15 minutes after the completion of the entire procedure. The sample obtained after the first unit of whole blood has been removed will show dilutional lowering of the uric acid concentration and the 15-minute equilibration sample will show dilutional lowering of the inorganic phosphorus concentration. Short-term donors and long-term donors manifest a somewhat different hemodilutional response to plasmapheresis.