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Biomedical subjects

S Kohn

Publications and source records attributed to S Kohn.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Postoperative analgesia: epidural injection of dexamethasone sodium phosphate].

Epidural administration of steroids has been suggested for the prevention of postoperative epidural fibrosis after lumbar lamino-arthrectomy. In order to assess the efficacy of this technique on pain occurring after such surgery, the demand of pentazocine during the first 24 postoperative hours was studied in 39 patients randomly assigned to two groups. Pain intensity was assessed by a five-point verbal scale (0: none; 1: poor; 2: moderate; 3: severe; 4: very severe) at five intervals (0-4, 5-8, 9-12, 13-16 and 17-24 h). The patients in group T (n = 20) did not receive any steroid, whereas those in group C (n = 19) were given, just after the end of surgery, a single dose of dexamethasone (4 mg) via an epidural lumbar catheter previously inserted by the surgeon. In group T, 18 patients required one or several intramuscular injections of pentazocine, whereas only three patients of group C (p less than 0.001) did so. Patients in group T expressed more severe pain (4 moderate, 12 severe, 3 unbearable) than those patients who had received steroids (1 moderate, 1 severe, 1 unbearable). As a consequence, they requested more pain killer (30 injections vs 8 injections, respectively; p less than 0.001) and sooner than patients of the steroid group (8 h vs 12 h; p less than 0.05). It was concluded that epidural administration of dexamethasone was helpful in preventing postoperative pain after lumbar lamino-arthrectomy.

Adult↗
PubMed1988

Cisplatin ototoxicity in guinea pigs with special reference to toxic effects in the stria vascularis.

The toxic effects of cisplatin (cis-diamminedichloroplatinum [II]) on the organ of Corti are well established. Few and conflicting data on this drug's effects on the stria vascularis exist. The present study presents animal experiments on the toxic effects of cisplatin in the stria vascularis and in the organ of Corti. Cisplatin-induced toxicity in albino and pigmented guinea pigs was evaluated morphologically and functionally, using light and transmission electron microscopy as well as auditory brainstem-evoked potentials on the organ of Corti and the stria vascularis. The results showed variability in hearing thresholds, ranging from no change to hearing loss of 30 dB, and prominent damage in the organ of Corti and in the stria vascularis. The toxic effects to both the organ of Corti and the stria vascularis should be considered when cisplatin is used in chemotherapy.

Animals↗
PubMed1986

Words created by children versus aphasic adults: an analysis of their form and communicative effectiveness.

The creation of words through the novel combination of English morphemes (e.g., "map ball" to refer to a globe) was studied in 40 preschool children, 40 grade school children, and 40 adults. These lexical innovations were collected while subjects named pictured objects, and were evaluated in terms of incidence, communicative effectiveness, novelty, semantic accuracy, and certain linguistic characteristics. Preschool children's innovations were as communicatively effective as those of grade school children and adults and contained the highest proportion of innovations with redundant elements. Grade school children produced the highest proportion with semantic inaccuracies. This suggests that preschoolers invent words from a limited set of highly familiar terms, whereas grade schoolers rely more on partially known terms. In addition, the children's innovations differed significantly from those previously collected from aphasic adults. This demonstrates that aphasia does not cause a regression to an early level of linguistic sophistication.

Anomia↗
PubMed1986

Quantitative analysis of tight junctions and the uptake of 99mTc in human gliomas.

The structural dimensions of capillary tight junctions and the uptake of 99mTc pertechnetate in human gliomas were studied. Quantitative analysis revealed a correlation between the uptake of radionuclides and the length of endothelial tight junctions. It is suggested that brain scintigraphy might be used for the selection of malignant brain tumors with altered tight junctions which might be accessible to chemotherapy with water-soluble agents.

Blood-Brain Barrier↗
PubMed1984

Epidermal Langerhans' cells in Behçet's disease.

Langerhans' cells were studied in the epidermis of two patients with active Behçet's disease and compared with those in two normal controls. Ultrastructural morphology and the percentage of Langerhans' cells found were similar in patients' (1.88%) and the control epidermis (1.79%). The density of Langerhans' cells in adjacent sites of the same epidermis was not homogeneous, being in the range of 0.8-2.8% in Behçet's disease and 0.6-4% in the controls. In the controls, Langerhans' cells were distributed unevenly. Some were located near the basal layer of the epidermis while the rest were in the mid and upper layers. In Behçet's disease most Langerhans' cells were in the mid-epidermis, but some were immediately beneath the stratum granulosum. In the Behçet's disease epidermis the area occupied by Langerhans' cells was increased by about 25% and the number of granules found increased by about 44%. It is suggested that in Behçet's disease the Langerhans' cells are in a more active state.

Adolescent↗
PubMed1984

The blood-tissue barrier of human brain tumors: correlation of scintigraphic and ultrastructural findings: concise communication.

Through the first 2 hr, uptake of [Tc-99m]pertechnetate and of Co-57 bleomycin were assessed in 29 brain tumors and were correlated with the ultrastructure of the tumor's capillary endothelium. No difference in uptake was found between the two tracers. Permeability of brain tumors to these agents was found to be governed by the same ultrastructural features that determine permeability in experimental brain tumors: the type of junction between contiguous endothelial cells in the capillaries. Meningiomas, which showed very high uptake of the radiotracers, demonstrated open or punctate junctions with short fusion of apposed membranes. They also showed a large number of pinocytotic vesicles and fenestrae. Capillaries of tumors without uptake had a small number of short tight junctions (less than 0.25 mu) between adjacent endothelial cells and a relatively large number of long junctions (greater than 0.5 mu). In intracerebral tumors that showed relatively high uptake, the reverse was true: most of the junctions were short and only a few long junctions were found. That uptake of [Tc-99m]pertechnetate and of Co-57 bleomycin depends on tumor capillary ultrastructure (which determines the permeability) suggests the possibility of the use of radiopharmaceuticals as in vivo indicators of tumor permeability. Brain scintigraphy may help to asses brain-tumor availability to non-lipid-soluble chemotherapeutic drugs.

Bleomycin↗
PubMed1983

Lexical creativity during instances of word-finding difficulty: Broca's vs. Wernicke's aphasia.

Lexical innovation--the creation of a word by combining existing morphemes in a novel way (e.g. "map ball" for "globe")--was evaluated as a method for circumventing word-finding difficulty in Broca's and Wernicke's aphasia. Aphasic groups were matched for naming performance and compared to a control group of normal adults matched for age and education. Lexical innovations were collected during the administration of a confrontation naming test, and were then analyzed in terms of the correctness of morpheme combination, semantic accuracy, novelty, and communicative effectiveness. An innovation was considered to be communicatively effective when its intended referent was understood by a naive judge. The lexical innovations of the two aphasic groups were diametrically opposed: as compared to both Broca's aphasics and normal adults, Wernicke's aphasics innovated significantly less often, and their innovations were significantly inferior in terms of: semantic precision, the proper construction of morpheme combination, and communicative effectiveness. This pattern suggests that lack of verbal fluency may be compatible with lexical creativity, while empty logorrheic speech may be an impediment to lexical creativity. Similarly, we conclude that the agrammatism of Broca's asphasia does not interfere with lexical innovation, while the paragrammatism of Wernicke's aphasia does interfere with lexical innovation, thus suggesting that paragrammatism affects morpheme combination at the word level as well as the sentence level.

Aphasia↗
PubMed1983

Radiofrequency hyperthermia: the design of coil transducers for local heating.

Simple and complex coils have been designed and built for use as radiofrequency transducers for local and regional hyperthermia. The heating from such coils is produced by currents generated in the dielectric by the electromagnetic field radiated from the coil elements. The heating rate profile, as a function of phantom depth, is dependent upon the size and geometry of the coil, its proximity to the dielectric, and the transducer current. Since the fields of simple pancake coils are inhomogeneous, either complex geometries or some method of smoothing is required. A simple solution is to move the coil over the region to be heated or to use multiple applicators. However, many satisfactory heating patterns have been derived for stationary coils designed to heat well-defined subcutaneous volumes to a depth of 3-5 cm. Thermometry studies in static saline-gelatin phantoms demonstrate extensive heating ranges and flexibility since the coils couple with the dielectric through air.

Diathermy↗
PubMed1979

The interaction between heparin and plasmin on amidolysis.

The effect of the interaction between heparin and plasmin not only on fibrinolytic, caseinolytic and esterolytic activities but also on amidolytic activity, since plasmin has amidolytic or amidase activity, was investigated. Following were the results obtained from these investigations: 1. Heparin enhanced amidolytic activity of a fixed level of plasmin which was prepared by activating plasminogen with urokinase within the range from 2 to 64 units/ml of the final concentration of heparin. 2. Heparin also enhanced amidolytic activity of a fixed level of plasmin which was prepared by converting plasminogen with insolubilized urokinase. 3. Heparin did not enhance or inhibit fibrinolytic, caseinolytic and esterolytic activities of a fixed level of plasmin which was prepared by activating plasminogen with urokinase, in the fibrinolytic activity within the range from 0.032 to 125 units/ml, in the caseinolytic activity within the range from 0.0125 to 100 units/ml, and in the esterolytic activity within the range from 0.016 to 128 units/ml, of the final concentration of heparin respectively.

Amides↗
PubMed1977

A method for the measurement of fibrinolytic activity based on one dimensional diffusion using small glass tubes. II. With special reference to the differences between the use of plasminogen-rich fibrinogen and that of plasminogen-free fibrinogen as the substrates.

The optimal conditions for the measurement of the fibrinolytic factors of plasma were examined using human and bovine plasminogen-rich fibrinogen or plasminogen-free fibrinogen as the substrates using the one dimensional diffusion method. The results were as follows: 1. There was no essential difference found between using human or bovine fibrinogen. 2. The levels of proactivator-plasminogen and plasminogen could be measured while using either plasminogen-rich or plasminogen-free fibrinogen. But, in using the latter, the proactivator-plasminogen level could not be measured, if a final concentration of more than 2,000 Christensen units of streptokinase were employed. 3. When using plasminogen-rich fibrinogen, anti-plasmin(s) and anti-activator(s) could be measured while using urokinase and plasmin, but not while using streptokinase. However, further study should be given to the measurement of the inhibitors, when using plasminogen-free fibrinogen.

Animals↗
PubMedDate not supplied

Rapid dose calculations for stereotactic radiosurgery.

A three-dimensional dose calculation algorithm is described for stereotactic radiosurgery using multiple noncoplanar beam arcs. Precalculated dose libraries of 20-deg arc segments, or mini arcs, are stored in computer memory which permits rapid calculation of complete, high resolution, three-dimensional isodose distributions and dose volume histograms. Three-dimensional patient contours and target volumes are obtained from CT scans and angiographic x rays. Rapid dose calculations are made possible by the use of arc libraries and an improved algorithm for mapping beam doses to the dose calculation grid. This permits more flexibility in designing optimum treatment plans, as five-six complete plans can be generated in less than 1 h. Thus many possible treatment options can be tested in the 3-4-h time period typically available in stereotactic procedures between CT scanning and treatment.

Algorithms↗
PubMedDate not supplied

Effect of centrifuge speed, refrigeration medium, and sperm washing medium on cryopreserved sperm quality after thawing.

Cryopreservation and subsequent thawing of semen for assisted reproductive procedures decreases sperm motility; motility further reduces when the cryoprotectant medium is removed because of the osmotic shock and centrifugation done to prepare the sperm. To compare motility and thus pregnancy rates, this study examined the effects of adding an additional refrigeration medium and three different centrifugation speeds for sperm preparation. Semen samples from 16 healthy normal volunteers were obtained by masturbation after 48 h of abstinence. Sperm motility and other motion characteristics were analyzed with a computer-assisted semen analyzer before freezing, after thawing, and after centrifugation. Each sample was divided into 6 aliquots and frozen using the liquid nitrogen vapor method. After thawing, human tubal fluid (HTF) with 5% human serum albumin was added to 3 aliquots, and refrigeration medium (identical to freezing medium without glycerol) was added to the remaining 3 tubes for each specimen. The tubes containing the two media were then washed by centrifugation at 100 g, 300 g, and 500 g for 10 min. Aliquots with refrigeration medium did not significantly differ from those with HTF for percent motility, curvilinear velocity, straight-line velocity, and amplitude of lateral head displacement at any centrifugation speed. Motile sperm count was significantly greater only at 100 g and 300 g for refrigeration medium (p = .02 and .01) and HTF (p = 0.001); at 300 g, average path velocity in refrigeration medium aliquots (p = .01) and linearity in HTF (p = .01) were greater. The results indicated that the reduction in motility and other motion characteristics probably cannot be overcome by changing factors such as the sperm preparation medium or centrifugation speed. More effective cryopreservation techniques or preparation methods that eliminate centrifugation need to be developed.

Centrifugation↗