No abstract available.
Rabbits*

No abstract available.
Rabbits*

No abstract available.
Rabbits*

No abstract available.
Rabbits*

No abstract available.
Rabbits*

The purpose of this study was to evaluate exophytically vertical bone formation in rabbit calvaria by the concept of guided bone regeneration with a custom-made porous titanium membrane combined with bone graft materials. For this purpose, a total of 12 rabbits were used, and decorticated calvaria were created with round carbide bur to promote bleeding and blood clot formation in the wound area. Porous titanium membranes (0.5 mm in pore diameter, 10 mm in one side, 2 mm in inner height) were placed on the decorticated calvaria, fixed with metal pins and covered with full-thickness flap. Experimental group I was treated as titanium membrane only. Experimental group II,III,IV was treated as titanium membrane with BBM, titanium membrane with DFDB and titanium membrane with FDB. The animals were sacrificed at 8 and 12 weeks after surgery, and new bone formation was assessed by histomorphometric as well as statistical analysis. 1. Porous titanium membrane was biocompatable and capable of maintaining the regeneration space. 2. At 8 and 12 weeks, all groups demonstrated exophytic bone formation and there was a statistical significant difference among different groups only at 12 weeks. 3. The DFDB group revealed the most new bone formation compared to other groups (p<0.05). 4. At 12 weeks, DFDB and FDB groups showed the most significant resorption of graft materials (p<0.05). 5. The BBM was not resorbed at all until 12 weeks. 6. The fixation metal pin revealed excellent effect in peripheral sealing. On the basis of these findings, we conclude that a porous titanium membrane may be used as an augmentation membrane for guided bone regeneration, and DFDB as an effective bone forming graft material. The fixation of the membrane with pin will be helpful in GBR technique. However, further study is required to examine their efficacy in the intraoral experiments.
Rabbits ; Animals

To understand the mechanism of cell injury when exposed to HgCl2, monitoring of cytosolic ionized free Ca2+([Ca2+]i), viability test, measurement of the amount of ATP, and Ca-ATPase activity were evaluated in cultured rabbit renal tubular cells(RTC) exposed to HgCl2. The results were as follows: 1) HgCl2 was cytotoxic to rabbit RTC at all doses except 10 uM and the rate of killing displayed a dose- and time-dependent relationship. 2) The absence of extracellular Ca provided partial protection from irreversible injury induced by HgCl2. 3) The increasing pattem of [Ca2+]i varied according to the concentrations of HgCl2. At the low concentrations of HgCl2 (2.5-10 microM), the level of [Ca2+]i increased slowly over the flat 2-3 min and then achieved plateau-state. In contrast, at the high concentrations of HgCl2 (25-100 microM) the level of [Ca2+]i achieved peak within 1 min and then decreased to a plateau state under normal concentrations. 4) The level of ATP was decreased to 27.5% of that of normal control cells within 3 min by using a treatment of 100 microM HgCl2. 5) HgCl2 did not affect the Ca2+ ATPase activity by enzyme histochemical observation. These findings suggest that the elevation of [Ca2+]i in response to the HgCl2-induced injury is an important event in accelerating injury that ultimately leads to cell death. But other possibilities such as HgCl2 might have direct deleterious effects on the also should be considered.
Rabbits ; Animals

The author carried out an experimentation to clarify a possible pathogenesis of renal papillary necrosis induced by an univisceral Shwartzman reaction. The experimental animals were healthy white rabbits in weighing between 1.7 kg and 3.0 kg. Under the condition of ureterostomy, animals were pretreated with 0.5 cc of 50% ethyl alcohol and followed by administration of 0.2 ~ 1.5 mg endotoxin (E. coli 026 : B6, bacto lipopolysaccharide B. Difco, U.S.A.) as preparation in the renal pelvis. And then sacrificed at 10 minutes, 30 minutes, 1 hour, 2 hours, 6 hours and 24 hours after intravenous injection of 0.2 mg or 0.6 mg endotoxin through the ear veins, subjection to examine light and electron microscopically. The obtained results were summarized as follows: Papillary necrosis was developed in 88% among 18 cases excluding 6 cases died before sacrification. There were two types of necrosis, namely papillary and medullary type, but the former and combined forms of both types were the most common findings. Initial main target site of injury in renal papilla induced by endotoxiin was the endothelium of vasa recta and then followed by the Henle's loop, interstitial cell and collecting tubule respectively. Vascular injuries such as swelling and detachment of endothelium were observed since 10 minutes after endotoxin injection. Henle's loop showed stratification of basement membrane without consistent features with time lapses and initially observed fatty vaculoes at 1 hour after endotoxin injection were more eminent in 24 hours group. Main changes of interstitial cells were decrease of lipid droplets while increase of fatty vacuoles; the latter were initially observed in 1 hour group and more eminent in 24 hours group. Collecting tubule showed many fatty vacuoles especially in 24 hours group. It is thought that emergence of fatty vacuoles seems to be a kind of immature lipid droplets to compensate the increased demand of PC release due to continuous ischemic condition. In conclusion, it is thought that ischemic injury due to the vascular changes is pathogenic mechanism producing renal papillary necrosis. Endotoxin induced univisceral Shwartzman reaction in the kidney may be a good experimental model in studying renal papillary necrosis.
Rabbits ; Animals

The Naka-Rushton equation, R=R(max) I(n)/(I(n)+K(n)), has been used to describe the luminance-response function of the scotopic electroretinogram. R(max) is the asymptotic value of the b-wave amplitude as a function of stimulus luminance, K is the intensity that produces a b-wave amplitude that is one-half R(max) and n is a dimensionless contant that controls the slope of the function and represents the degree of homogeneity of retinal sensitivity. These three parameters are often used in experimental laboratories, since it can show selective changes in each parameter. The present study describes and compares the parameters of Naka-Rushton equation obtained by using ganzfeld stimuli(R(max)=363+/-32 uv, n=0.86+/-0.06, log K=-2.39+/-0.19 log cd.sec/m2) and direct flash stimuli(R(max)=354+/-28 uv, n=0.80+/-0.06, log K=-2.26+/-0.15 log cd.sec/m2) in 20 eyes of the normal pigmented rabbits respectively. The n values were significantly increased by the ganzfeld light stimuli than by the direct flash stimuli(p<0.05).
Rabbits ; Retinaldehyde

Ten pigmented raqbits were dark adapted for 30 minutes previously and then exposed to room illumination of 200 lux for 10 seconds. In mesopic adaptation, the oscillatory potentials(OPs) were recorded. The coefficient of variation in the peak latency, time interval, summed amplitude, and amplitude of each individual OP wavelet were obtained. The peak latency showed the smallest coefficient of variation. The summed amplitude of the OPa and the time interval showed smaller coefficient of variation than amplitude of each individual OP component. Therefore the peak latency, summed amplitude, and time interval may be reliable factors to evaluate the OPs. The increase of the light stimulus did not affect the amplitude of O3. However, O1 and O2 tended to increase in amplitude and O4 to decrease as the intensity of light stimulus increased. These facts may suggest that each individual component of OP has different orign. As the intensity of light stimulus increased, the summed amplitude of OPs was increased and peak latency of O1, O2, O3, and O4 were decreased. Time intervals showed no significant changes.
Lighting ; Rabbits*