Synthesis and biological activities of some new 4,5-dihydro-1H-1,2,4-triazol-5-ones

The reactions of 3-alkyl(aryl)-4-phenylamino-4,5-dihydro-1H-1,2,4-triazol-5-ones with appropriate alkyl halides via sodio derivatives were studied and the corresponding 1-alkyl-3-alkyl(aryl)-4-phenylamino-4,5-dihydro-1H-1,2,4-traizol-5 -ones were synthesized. Next, the new compounds were tested for their in vitro antimicrobial activities.

Rapid, widespread, and longlasting induction of nestin contributes to the generation of glial scar tissue after CNS injury

Neuronal regeneration does generally not occur in the central nervous system (CNS) after injury, which has been attributed to the generation of glial scar tissue. In this report we show that the composition of the glial scar after traumatic CNS injury in rat and mouse is more complex than previously assumed: expression of the intermediate filament nestin is induced in reactive astrocytes. Nestin induction occurs within 48 hours in the spinal cord both at the site of lesion and in degenerating tracts and lasts for at least 13 months. Nestin expression is induced with similar kinetics in the crushed optic nerve. In addition to the expression in reactive astrocytes, we also observed nestin induction within 48 hours after injury in cells close to the central canal in the spinal cord, while nestin expressing cells at later timepoints were found progressively further out from the central canal. This dynamic pattern of nestin induction after injury was mimicked by lacZ expressing cells in nestin promoter/lacZ transgenic mice, suggesting that defined nestin regulatory regions mediate the injury response. We discuss the possibility that the spatiotemporal pattern of nestin expression reflects a population of nestin positive cells, which proliferates and migrates from a region close to the central canal to the site of lesion in response to injury.

Cutting directions of bone with biomaterials in situ does influence the outcome of histomorphometrical quantifications

Ten commercially pure titanium implants were inserted in the tibia of ten mature New Zealand white rabbits for a healing period of 3 months. Cut and ground sections were performed on transversely and longitudinally cut tibia bone with implants in situ. Each implant with surrounding bone was processed by (a) dividing it into two parts by cutting transversely through the tibia and then (b) cutting one of the implant halves longitudinally through the tibia. In both cases 10 microns sections were made. Computerized histomorphometrical calculations of the bone-to-metal contact and the bone area in the threads were performed and comparisons of the differently cut sections were made for the same implant. Larger amounts of bone-to-metal contact and bone area in the threads were observed in the longitudinally cut samples in comparison to transversely cut ones. A strong statistically significant difference was obtained when comparing the transversely with the longitudinally cut samples with respect to bony contacts in the cortical region, demonstrating 25% more bone-to-metal contact lengths in the longitudinal cutting direction of the tibia. Quantitative histomorphometrical comparisons should, therefore, be performed on samples that are cut in the same direction.

Spinal axons in central nervous system scar tissue are closely related to laminin-immunoreactive astrocytes

Although transected central nervous system axons fail to regrow after injuries in adult mammals, they send sprouts into the scar tissue that forms at the lesion. We have investigated the relation between scar cells, laminin-like immunoreactivity and cut spinal axons in two previously characterized spinal cord lesion types. Labeling with antisera to glial fibrillary acidic protein and laminin demonstrated that the scar tissue formed after lesions in the rat and cat dorsal and ventral funiculi showed prominent gliosis and strong laminin-like immunoreactivity four days to one year postlesion. Axonal sprouts in the scar, visualized with antibodies to neurofilament (RT97) or by tracing using fluorescein-conjugated dextran, were ensheathed by a thin layer of strongly laminin-immunoreactive tissue. Immunoelectron microscopy demonstrated that axons in the scar were ensheathed predominantly by astrocytes, and that the surface of the cells outlining the axons in the scar showed strong laminin-like immunoreactivity. Adhesive and neurite orienting properties in the scar tissue were assessed in an in vitro system where PC12 cells were cultured on spinal cord slices from dorsal funiculus-lesioned rats. Very few cells adhered to the spinal cord section except for the part where the scar tissue had formed, where numerous cells were attached. The PC12 cells that had adhered to the scar tissue were mainly seen in parts of the scar that showed laminin-like immunoreactivity and their neurites predominantly followed tissue showing laminin-like immunoreactivity. The close association between axonal sprouts and laminin-like immunoreactivity indicates a role for laminin in axonal growth and/or guidance in the injured spinal cord.

Importance of ground section thickness for reliable histomorphometrical results

Ten screw-shaped commercially pure titanium implants were inserted in 10 rabbit tibia. The implants with surrounding bone were harvested after 12 weeks. The samples were processed to be cut and ground. Histomorphometrical analyses of the bone-to-metal contact and the bone area around the entire implants were performed on transvertically cut sections at intervals, starting with 100 microns thick sections; then the same sections were further ground down to 50, 30 and 10 microns. The thicker the section the more bone-to-metal contacts were demonstrated. A statistically significant difference was obtained when comparing the 100-30, 100-10, 50-30 and the 50-10 microns thick sections. Comparing the area measurements of 100-10, 50-30, 50-10 and 30-10 microns revealed a statistically significant difference. Bone-to-metal contact measurements on ground sections that are too thick (over 30 microns) may result in overestimations of the 'true' bony contacts.

A histomorphometric evaluation of bone-to-implant contact on machine-prepared and roughened titanium dental implants. A pilot study in the dog

This investigation was performed to assess the bone-to-implant surface contact at fixtures of titanium that either had a standard machine prepared or a TiO2-blasted surface. Five beagle dogs were used in the experiment. Extractions of the premolars were performed in the maxilla. After 4 months of healing, 5 standard machine-prepared fixtures and 5 prepared according to the TioBlast technique were inserted. Two months later another 5 "standard" and 5 TioBlast-prepared implants were inserted. Four months after the first fixture installation, the animals were killed and ground sections prepared from each implant site. Of the 20 implants installed, 19 were successfully incorporated. The mean bone-to-implant surface for "standard" fixtures was about 40% both at the 2 and 4 months observation interval. The corresponding figures for the TioBlast-prepared fixtures were similar during the first 2 months of observation, while subsequently the TioBlast-prepared fixture surface seemed to stimulate to a more close bone-to-implant contact (65%) than the "standard" one.

Healing of implant dehiscence defects with and without expanded polytetrafluoroethylene membranes: a controlled clinical and histological study

Bone augmentation around implant fixtures using the technique of guided tissue regeneration has been described in a number of reports. The aim of this study was to evaluate bone fill around dehiscence defects at matched defects randomly allocated to test (expanded polytetrafluoroethylene; Gore-Tex) or control treatments within the same patient. Six edentulous subjects were treated with overdentures supported by 2 fixtures ad modum Bränemark. In addition, 2 experimental 7-mm fixtures with nearly identical dehiscence defects on the labial aspect were placed in the anterior part of the mandible. Baseline defect heights ranged from 2.5 to 4.0 mm with 2 to 4 threads exposed. The test fixture dehiscence was covered with a Gore-Tex membrane secured with a cover screw. The experimental fixtures were exposed after 5 months at stage 2 surgery and measurements and photographs repeated. The fixtures were then removed with a trephine and processed for histological evaluation. Regeneration of a hard tissue resembling bone was observed in 4 of 6 cases treated with Gore-Tex, amounting to between 95 and 100% elimination of the dehiscence and total coverage of the threads. However, in one of these cases, histological evaluation showed that it was soft tissue and not bone, and in a further case soft tissue regeneration was apparent both clinically and histologically. In another case there was no significant regeneration at either test or control defects. Although there was a trend for the Gore-Tex-treated dehiscences to respond more favourably, the differences in clinical and histological measurements between test and control failed to reach statistical significance.

A removal torque and histomorphometric study of commercially pure niobium and titanium implants in rabbit bone

Screw-shaped commercially pure (c.p.) niobium and c.p. titanium implants were inserted in rabbit bone. After a healing period of 3 months, a significantly higher removal torque was demonstrated to unscrew the niobium implants (average 32.9 Ncm) compared to the c.p. titanium implants (average 25.3 Ncm). In the histomorphometric part of the study, there were no significant differences in bone-to-metal contact between the 2 implant materials. An average of 41.1% bony contact was demonstrated for the niobium screws compared to an average of 37.2% for the c.p. titanium ones. Our removal torque findings could be related to the differences that we observed between the 2 implant surfaces as indicated by SEM. Since niobium implants showed a more irregular surface topography and niobium is a softer metal than c.p. titanium, this seems the most probable reason for the differences observed in removal torque between the 2 metals. Hypothetically, a more "positive biocompatibility" of the c.p. niobium in comparison to the c.p. titanium remains as another possible reason for the observed differences. However, against such a difference in biocompatibility between c.p. niobium and c.p. titanium, there is the very similar amount of bony contact registered in the histomorphometric analysis.

Qualitative interfacial study between bone and tantalum, niobium or commercially pure titanium

Tantalum (Ta), niobium (Nb) and commercially pure titanium (c.p. Ti) were sputtered on to the surfaces of polycarbonate plastic implants. After 3 month of insertion, in the tibial metaphysis of rabbits, the implants were removed with a surrounding bone collar and processed for light (LM) and electron microscopy (EM). By EM a zone of ground substance tens of nanometers wide without collagen filaments was noticed surrounding the Ta implants. Multinucleated macrophages could occasionally be recognized in the interface zone. Foreign body reactions were more striking at the Nb interface while no multinucleated macrophages were observed in the c.p. Ti interface. The ground substance layer had a thickness in the range of 40-60 nm for the Nb implants, whereas in c.p. Ti sections the collagen filaments were noticed 20-40 nm from the metal surface. There are more subtle differences between tantalum and c.p. titanium than between c.p. titanium and niobium which seems to be less well tolerated when implanted in bone.

[House dust mold in Istanbul. I. Detection of mold flora in bed dust]

In our study, mycological analyses were carried out on 110 randomly chosen houses for bed dusts. 748 mould strains belonging to 117 genus and species were isolated and identified. Air-borne pathogenic fungi, fungi that are causative agents of pulmonary allergy such as Cladosporium spp., Aspergillus glaucus group, Alternaria, Ulocladium, Aureobasidium pullulans, Aspergillus niger group were isolated.

Long-term effects of spinal cord transection on fast and slow rat skeletal muscle. I. Contractile properties

Contractile properties of rat soleus and extensor digitorum longus muscles were studied 1 year after complete thoracic spinal cord transection (spinal cord level T9). Force-generating capacity and contraction speed were unchanged in the extensor digitorum longus 1 year after transection. However, the rate of contraction and relaxation increased in the soleus as reflected by a decrease in time-to-peak tension and increase in fusion frequency. Additionally, the soleus muscle cross-sectional area decreased significantly (50%) while generating the same absolute tension. Thus, a large increase in soleus specific tension (force per unit area) was observed. These data, in conjunction with the increase in contractile speeds, suggest soleus slow-to-fast fiber type conversion secondary to cordotomy. Discriminant analysis of the contractile properties yields fusion frequency as the best discriminator between muscle groups. Thus, following cordotomy, predominantly slow muscles are affected to a greater extent than fast muscles.

Decompression of an experimental compartment syndrome in dogs with hyaluronidase

The treatment of compartment syndromes in which elevation of intracompartmental pressure occurs is by surgical fasciotomy. This is a relatively simple procedure but may be associated with complications. This study aimed at developing an alternative method to decompress a compartment by use of the enzyme hyaluronidase. Autologous plasma was infused into the anterolateral leg compartments of six dogs to simulate compartment syndromes of 80 mmHg. Pressure decay after pressurization was recorded. The compartment pressures were then again raised to 80 mmHg by subfascial injections of 1500 units hyaluronidase in 2 ml saline injected into one compartment and 2 ml saline only into the control side. Pressure decay was again recorded. On the experimental side, a significantly faster decay rate occurred after hyaluronidase injection than after initial pressurization; 8.0 +/- 1.3 (S.E.M.) versus 3.4 +/- 0.4 (S.E.M.) mmHg/min (p less than .01). Pressure decay after hyaluronidase injection was significantly faster than after the same volume injection on the control side, over both a four-minute period (8.0 +/- 1.3 [S.E.M.] versus 4.1 +/- 0.6 [S.E.M.] mmHg/min [p less than .03]) and a 25-minute period (2.1 +/- 0.3 [S.E.M.] versus 1.3 +/- 0.1 [S.E.M.] mmHg/min [p less than .03]). Hyaluronidase removes hyaluronic acid molecules from the leg compartment fascia and, by facilitating fluid flow from the compartment, causes decompression. Hyaluronidase may then have a place in the prophylaxis and treatment of compartment syndrome, thus avoiding anesthesia and surgery.