Use of algal fluorescence for determination of phytotoxicity of heavy metals and pesticides as environmental pollutants

The phytotoxicity of heavy metals and pesticides was studied by using the fluorescence induction from the alga Dunaliella tertiolecta. The complementary area calculated from the variable fluorescence induction was used as a direct parameter to estimate phytotoxicity. The value of this parameter was affected when algae were treated with different concentrations of mercury, copper, atrazine, DCMU, Dutox, and Soilgard. The toxic effect of these pollutants was estimated by monitoring the decrease in the complementary area, which reflects photosystem II photochemistry. Further, the authors have demonstrated the advantage of using the complementary area as a parameter of phytotoxicity over using variable fluorescence yield. The complementary area of algal fluorescence can be used as a simple and sensitive parameter in the estimation of the phytotoxicity of polluted water.     

Effects of d-amphetamine injected into the nucleus accumbens on ethanol reinforced behavior

Rats, initiated to self-administer 10% (v/v) ethanol in an operant situation using the sucrose-fading procedure, received bilateral n. accumbens microinjections of d-amphetamine prior to operant sessions. Doses of 4 micrograms, 10 micrograms and 20 micrograms/brain were administered and some animals also received a 4 microgram/brain dose of LY171555. Three different effects were observed: increased, decreased and no change in total session responding. There was no clear relation between injection area in the n. accumbens and type of effect observed. For either an increase or decrease in total session responding, momentary response rates were decreased. Both d-amphetamine and LY171555 produced similar results. The data support the hypothesis that dopamine in the n. accumbens is involved with ethanol reinforced operant responding but in a complex manner.     

The histopathology of freezing injury to the rat spinal cord. A light microscope study. I. Early degenerative changes

In an effort to develop a method of tissue injury which would provide a model for the study of axonal regrowth in adult mammalian central nervous system (CNS), we have analyzed the effects of freezing in the dorsal columns of more than 200 rat spinal cords. The effects of temperature and time of exposure upon the size, shape, distribution and histologic characteristics of the lesion have been assessed during the first seven days following the injury. The upper threshold for injury occurs at -3 degrees C for 15 minutes. Between -3 degrees C and -12 degrees C the tissue changes vary in extent and characteristics. Selective damage to axons and myelin occurs with sparing of the supportive cells followed by proliferation of a cellular matrix. At seven days, the lesions produced by -8 degrees C for 15 to 60 minutes have neither axons nor myelin sheaths and consist of a dense cellular matrix of macrophages and presumed glial cells. With these tissue characteristics, and the preservation of tissue continuity without obstructive barriers, this model would appear to be potentially suitable for the study of axonal regrowth potential in mammalian CNS.     

Intracarotid hydroxyethyl methacrylate solution causing stroke in dogs

Hydroxyethyl methacrylate (HEMA) has been advocated as a polymerizing solution with which to prevent deflation of detachable balloons in interventional neuroradiology. It is pertinent to know if unpolymerized HEMA would have untoward effects if accidentally released into the carotid artery by balloon rupture or deflation. Seven mongrel dogs underwent transfemoral catheterization of the common carotid artery and subsequent injection of HEMA solution in volumes of 1 cc in five dogs, 2 cc in one, and 4 cc in one. Angiography performed at the time of injection revealed evidence of intravascular thrombosis as well as possible spasm. Three surviving animals were sacrificed at 48 hours; the brains were fixed and examined histopathologically. One brain was normal and one was autolyzed and could not be examined. Five of the seven animals had histopathologically documented cerebral infarctions of varying size. No foreign substance was seen within the blood vessels to suggest intravascular polymerization. The animals injected with 2 or 4 cc HEMA solution did not survive 48 hours. Literature review reveals little documentation of the toxicology of intravascular HEMA. With its increasing popularity as a compound for polymerization in detachable balloons introduced into the brain, further investigations are warranted to understand the physical properties of the compound and potential risks of its use.     

Treatment of painful spondylolysis using Morscher's hook

An original technique of direct isthmic reconstruction described by E. Morscher was used in 25 patients with painful spondylolysis after failure of conservative treatment. After a follow-up of 25 months, the functional and radiological results were evaluated and compared with other techniques. Nineteen patients had an excellent or good functional result, in 2 patients the result was fair, and 4 patients had no beneficial effect on pain. The best results were seen in patients younger than 20 years, with an olisthy of less than 10 mm, without associated joint, disc or ligament pathology. In these cases, good results were achieved in 90%, and there was radiological consolidation in 100%.     

Local cerebral glucose utilisation in chronic alcoholics: a positron tomographic study.

Using positron tomography, a study of regional cerebral glucose utilisation was performed prospectively in a highly selected group of six neurologically unaffected primary chronic alcoholics. In this group, neuropsychological, behavioural and CT scan anomalies were comparable with those previously reported in more extensive studies. With respect to age-matched control values, cerebral metabolic rate was not significantly modified in the selected cortical, subcortical and cerebellar regions of interest. However, the metabolic regional distribution index, which reflects the distribution pattern of glucose utilisation, was selectively and significantly decreased in the medio-frontal area, pointing to a limbic metabolic dysfunction apparently linked to chronic alcoholism.     

Newly developed hybrid suture without lubricant: noninvasive in vivo assessment of biocompatibility with multiparametric MR imaging.

Magnetic resonance imaging (MRI) and magnetic resonance (MR) relaxometry were used to assess noninvasively the tissue response of a new uncoated hybrid braided suture made from a combination of ultra-high-molecular-weight polyethylene (UHMWPE) and polyester (polyethylene terephthalate) (PET) yarns in comparison to a silicone impregnated braided 100% polyester (PET) control suture (Ticron). Both biomaterials were monitored for a period of 30 days following implantation in both incised and nonincised paravertebral rabbit muscles. In all cases, MR images and relaxometry demonstrated that the hybrid suture elicited either a milder or a similar tissue and cellular response compared to the control suture. These findings were confirmed by conventional histological analysis of the surrounding tissues. They also demonstrated that the hybrid suture promoted faster healing in terms of collagen infiltration between the yarns and individual filaments. This milder inflammatory reaction and improved biocompatibility represent a real advantage in the healing performance of sutures for cardiac and vascular surgery, and support the need for continued research and development of hybrid structures. This study also demonstrated the ability of MRI techniques to noninvasively evaluate the biocompatibility of biomaterials. By extending the capacity of MR diagnostic tools from patients to experimental animals, it is now possible to validate the healing performance of foreign materials with statistical reliability and fewer animals.