Changes in the nature and composition of enamel mineral during procine amelogenesis

Summary The present study was undertaken to investigate changes in the crystalline structure and composition of procine enamel mineral during amelogenesis. Special attention was given to the carbonate location in the forming apatite crystal. Enamel samples were obtained from the outer (young) secretory, inner (old) secretory, maturation, and mature (hard) enamel of the permanent incisors of slaughtered piglets. The crystalline structure and composition of these enamel samples were studied using Fourier transform infrared spectroscopy, X-ray diffraction, and chemical analyses. The initial enamel mineral in the outer secretory enamel was rich in acid phosphate and carbonate. The carbonate was mainly substituted for phosphate groups in the apatite crystals of the early (outer) secretory enamel. Developmental advancement from the outer secretory to the inner secretory (as well as early maturation) stages brought about significant changes in crystal parameters, namely, shrinkage and expansion of thec anda unit cell dimensions, respectively, and the shift of av ₃ PO₄ band to higher wavenumbers in the FTIR spectrum. X-ray diffraction patterns indicated that mineralization during the tissue maturation was characterized by a gradual growth of enamel crystals parallel to thea-axis direction. A most prominent finding was that, with developmental advancement, a decrease in CO₃ per unit mass of P (or Ca) in the tissue, and a concomitant increase in the CO₃ occupying OH sites in the crystalline lattice became apparent. The overall results may reflect (1) changes in the composition of the medium in which precipitation of enamel carbonatoapatite occurs, (2) initial formation of an acid phosphate such as octacalcium phosphate-like mineral, or (3) modifications of the precipitating phase induced by changes in the kinetics of the mineral formation.     

Results of the treatment of patients with torsion of the sigmoid

The results of treatment of 204 patients with torsion of the sigmoid colon are analysed. Total postoperative mortality was 14.2%. Sixty-eight patients were subjected to palliative operations of the type of ++de-torsion or ++de-torsion in combination with mesosigmoplication and sigmopexy. In this group of patients, 20.5% underwent a second operation for a recurrence of the disease in different periods after the first operation. The mortality rate after palliative operations was 13.2%. Resection of the sigmoid colon with an end-to-end anastomosis was carried out in 87 patients. The postoperative mortality was 13.7%. There were no fatal outcomes among patients who were treated by radical operation carried out in a planned order of preliminary detorsion. In 11.7% of cases, sigmoid torsion was complicated by gangrene. Seven patients (29.1%) died in the postoperative period.     

Argon laser pretreatment in Nd: YAG iridotomy

Argon laser pretreatment prior to Nd:YAG laser iridotomy may decrease the incidence of operative hemorrhage. In a prospective, randomized clinical trial involving 12 patients (24 eyes), one eye was randomly assigned treatment with the Nd:YAG laser alone, while the other eye was pretreated with argon laser photocoagulation immediately prior to Nd:YAG laser. Eight of the 12 eyes (67%) treated with Nd:YAG laser alone had operative hemorrhages; only 2 of the 12 (17%) pretreated eyes did. Thus, argon laser pretreatment significantly reduced the incidence of hemorrhage during Nd:YAG iridotomy (P = .012).     

Reconstructive and restorative operations in iatrogenic injuries of the extrahepatic bile ducts

The results of diagnosis and treatment of iatrogenic injuries of the extrahepatic biliary tract in 47 patients are analysed. The injury was detected during the operation only in 6 cases, in 41 cases it was revealed on the 1st-6th postoperative day. Intensive conservative therapy was applied in the preoperative period to correct the values of homeostasis and metabolism. Special attention was attached to antibacterial therapy aimed at suppression of ++non-clostridial anaerobic infection. Sixty-three surgical interventions were conducted on 47 patients; 47 of them were restorative or reconstructive, 15 were undertaken for emergency indications, one, for developed postoperative complication. One patient died. Particular importance was attached to adequate draining both in emergency and in reconstructive and restorative operations.     

Hepatectomy in repeated operations on patients with parasitic diseases of the liver]

The results of resection of the liver in repeated operations on patients with parasitic disease of the liver are discussed. Operations were conducted on 22 patients with alveococcosis and 7 patients with echinococcosis. By means of the method of atypical liver resection radical operations were performed on 20 patients (69%) and palliative resections of the liver in 9 patients (31%). The palliative resections were combined with cryodestruction of the remaining parasitic tissue, which improved the therapeutic effect significantly and prolonged the patients' survival. The volume of the resection ranged from a segment to one half of the liver. The fatality rate was 6.8%.     

Changes in the levels of neuropeptide Y-LI in the external jugular vein in connection with vasoconstriction following subarachnoid haemorrhage in man

Summary NPY is a putative neurotransmitter mainly co-localized with noradrenaline in sympathetic fibers which innervate the cerebral vasculature. The origin of most of the perivascular NPY fibers seems to be in the superior cervical ganglion. To investigate involvement of Neuropeptide Y (NPY) mechanisms in subarachnoid haemorrhage (SAH), twenty patients with SAH were investigated. NPY-LI (-like immunoreactivity) levels in the external jugular vein were assessed using radioimmunoassay in blood samples collected postoperatively (or after SAH in non-surgical patients) on days 1, 2, 3, 5, 7 and 9. These levels were compared with the clinical course and blood flow velocity changes monitored with ultrasonic Doppler equipment from both middle cerebral arteries (MCA) and both internal carotid arteries (ICA).Compared to NPY-LI levels in 14 controls (mean 116±3 pmol/ l), increased levels (up to 253 pmol/l) and a close relationship between velocities and NPY-LI levels were found in a subpopulation of the SAH patients. When comparing the mean haemodynamic index (V MCA/ipsilateral V ICA) and mean NPY-LI levels in each of the 20 patients, a correlation of r=0.75, p=0.0001 was found. Increased NPY-LI were found (131±8 pmol/l) when simultaneous Doppler velocity recordings showed vasoconstriction (Haemodynamic index >5) compared with samples taken when the haemodynamic index was <5, p<0.05. When MCA velocity exceeded 120 cm/sec, increased levels were found (129±9 pmol/l) compared with the conditions when MCA velocity was less than 120 cm/sec (113±5 pmol/ l), p=0.06. The results indicate a possible NPY involvement in cerebral vasoconstriction after SAH.