Stereopsis from a performance perspective.

PURPOSE: A patient can demonstrate a poor stereoscopic test or task performance for reasons inherent within the test/task itself for reasons dependent on normal physiology common to all human subjects, and also for reasons that are outside of normal physiology and are unique or idiosyncratic to a particular person's visual system. This article reviews the literature for the first two reasons, but emphasizes the pathophysiology involved in the idiosyncratic and abnormal reasons. RESULTS: Using control systems analysis, it is shown that deficits in stereoscopic performance can be explained by reference to the quantitative aspect of stereoscopic threshold and qualitative aspects such as speed of response, reliability-robustness, and strength of percept. The relationship between fixation disparity and stereopsis is seen to be central to this explanation. CONCLUSIONS: Proceeding from diagnosis to treatment, control systems analysis offers physiologically based explanations for the corrective procedures necessary to ameliorate abnormal conditions. Several topics for applied research in stereopsis are suggested.     

The immediate results of laparoscopic treatment in perforated gastroduodenal ulcers

The article presents an analysis of immediate results of laparoscopic interventions (suturing, vagotomy) in 40 patients with perforated ulcers in the pylorobulbar zone. Postoperative complications were noted in 7.5% of the patients. There were no lethal outcomes. The authors recommend wider introduction of the laparoscopic technology as a method of optimization of surgical treatment for perforated ulcers.     

A methods of laparoscopic suturing of perforated pyloro-bulbar ulcers

The article describes a method of laparoscopic suturing perforated ulcers of the pylorobulbar zone. The elements of all steps of the operation are analyzed including the places of introducing the trocar, the method of putting the intracorporeal stitches, means of sanitation and drainage of the abdominal cavity. The method was successfully used in operations on 43 patients with perforated ulcers without any complications.     

Preliminary epidemiological survey of schistosomiasis in central and southern Liberia

Some basic epidemiological data on schistosomiasis in central and southern Liberia were collected. A study of snail density fluctuations was carried out in waterbodies bordering the road between Harbel and Gbarnga. Samples from schoolchildren living in ten selected villages were examined for Schistosoma spp. and other helminths. In the coastal region no snail hosts were found, the prevalence rates in schoolchildren were low and the infections were apparently imported. Inland, the intermediate host of Schistosoma haematobium Bulinus globosus was common and the prevalence of urinary schistosomiasis was high. Further inland, around Gbarnga, both Schistosma mansoni and S. haematobium were endemic. The seasonal patterns of patent cercarial infections in Bulinus globosus and Biomphalaria pfeifferi are described. Both snail densities and cercarial infection rates were markedly reduced by heavy rains. The results of the study may contribute to the planning of future integrated control strategy.     

Immunohistochemical characterization of biphasic synovial sarcomas

An immunohistochemical investigation of 12 primary biphasic synovial sarcomas was carried out. Highly frequent expression of vimentin, EMA and pan-cytokeratin (cytokeratin AE1/AE3) and low frequency of collagen type II and VI expression in the extracellular matrix of tumors were estallished.     

Preserved pharmacological activity of hepatocytes-treated extracts of valerian and St. John's wort

The two herbal extracts valerian (Valeriana officinalis L.) and St. John's wort (Hypericum perforatum L.) were studied for their metabolic changes upon incubation with freshly prepared rat hepatocytes and subsequently analysed phytochemically as well as pharmacologically in vitro. Quantitative HPLC analysis of valerian extracts revealed considerable metabolic activities with regard to sesquiterpenes and iridoids. The amount of acetoxyvalerenic acid decreased 9-fold, while that of hydroxyvalerenic acid correspondingly increased 9-fold due to O-deacetylation. The valepotriates didrovaltrate, isovaltrate and valtrate decreased 2-, 18- and 16-fold, respectively. However, the binding affinities of the incubated extracts to the benzodiazepine and picrotoxin binding site of the GABA (A) receptor were quite similar to those of the non-incubated extracts. Neither valerenic acids nor valepotriates exhibited any significant effect on the two binding sites when tested as single compounds. Therefore, either other constituents represent the active ones or multiple compounds are necessary for the observed inhibitory and allosteric effects at the GABA (A) receptor. Extracts of St. John's wort were less potently metabolised than valerian. The amount of pseudohypericin and the main flavonoids (hyperoside, rutin, isoquercitrin, quercitrin, quercetin and I3,II8-biapigenin) slightly decreased during the 4-h incubation period. Both the antagonist effect at the corticotropin-releasing factor (CRF) type 1 receptor and the binding inhibition at the 5-HT transporter were attenuated during the metabolic treatment. The reduced antagonist effect correlates with the decreasing amount of pseudohypericin known to be a CRF (1) receptor antagonist. In conclusion, the incubation of plant extracts with freshly prepared rat hepatocytes represents a useful approach to study the pharmacological action of metabolised plant extracts. The consistent pharmacological activity of both valerian and St. John's wort is concordant with the known clinical efficacy of pharmacological activities.     

Long-term results of closure of perforated pyloro-duodenal ulcers

Long-term results of closure of perforated ulcers were analyzed in 91 patients. Excellent and good results were obtained in 70% of the patients, in 12.1% the results were satisfactory. In 18.6% of the cases the results were considered unsatisfactory. Bad long-term results were due to the absence of dispensary follow-up, the absence of repeated courses of anti-ulcer therapy, and not following the recommendations on the treatment. Excellent and good long-term results observed in 70% of the patients allow recommendation of suturing the perforated opening and anti-ulcer therapy in patients with perforated pyloroduodenal ulcers.