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B C Levin

Publications and source records attributed to B C Levin.

27 records · Page 2Linked to original sources
PubMed1988

Direct sagittal CT in the evaluation of temporal bone disease.

The human temporal bone is an extremely complex structure. Direct axial and coronal CT sections are quite satisfactory for imaging the anatomy of the temporal bone; however, many relationships of the normal and pathologic anatomic detail of the temporal bone are better seen with direct sagittal CT sections. The sagittal projection is of interest to surgeons, as it has the advantage of following the plane of surgical approach. This article describes the advantages of using direct sagittal sections for studying various diseases of the temporal bone. The CT sections were obtained with the aid of a new head holder added to our GE CT 9800 scanner. The direct sagittal projection was found to be extremely useful for evaluating diseases involving the vertical segment of the facial nerve canal, vestibular aqueduct, tegmen tympani, sigmoid sinus plate, sinodural angle, carotid canal, jugular fossa, external auditory canal, middle ear cavity, infra- and supralabyrinthine air cells, and temporomandibular joint.

Adolescent↗
PubMed1988

Otogenic intracranial inflammations: role of CT.

This article reviews the authors' results using CT in the diagnosis of 18 selected patients who were clinically suspected of having otogenic intracranial complications, demonstrating with illustrative examples the important role of CT in diagnosing various stages of acute coalescent mastoiditis and its associated complications.

Adolescent↗
PubMed1988

Cholesteatoma of the middle ear and mastoid. A comparison of CT scan and operative findings.

High-resolution CT scanning accurately depicts the status of the structures of the temporal bone, allowing delineation of pathology prior to surgical exploration of ears with cholesteatoma. It provides information concerning location and extent of disease as well as possible anatomic variations and complications that may be encountered. The main advantages of CT scanning over polytomography are superior soft-tissue contrast resolution and improved spatial detail at a reduced radiation dose for the patient.

Bone Diseases↗
PubMed1987

Toxicological interactions between carbon monoxide and carbon dioxide.

Fischer 344 male rats were subjected to 30-min individual or combined exposures of carbon monoxide (CO) and carbon dioxide (CO2). All deaths from CO occurred during the exposures, and the LC50 values were 4600 and 5000 ppm, depending on experimental conditions. Animals exposed to CO2 concentrations ranging from 1.3 to 14.7% for 30 min were neither incapacitated nor fatally injured. The addition of nonlethal concentrations of CO2 (1.7 to 17.3%) to sublethal concentrations of CO (2500 to 4000 ppm) caused deaths of the exposed rats both during and following (up to 24 h) the 30-min exposures. The most toxic combination of these two gases (2500 ppm CO plus 5% CO2) increased the rate of carboxyhemoglobin (COHb) formation 1.5 times that found in rats exposed to 2500 ppm of CO alone. The COHb equilibrium levels were the same. Exposure to both CO and CO2 produced a greater degree of acidosis and a longer recovery time than that observed with either single gas. The results fit a mathematical model indicating a synergistic interaction. Combustion of 11 materials at their LC50 values indicated that CO was probably the primary toxicant in one case and that the combined CO plus CO2 was the cause of the deaths in three other cases. Additional fire gases need to be studied to explain deaths from the other materials.

Animals↗
PubMed1987

Effects of exposure to single or multiple combinations of the predominant toxic gases and low oxygen atmospheres produced in fires.

The toxicity of single and multiple fire gases is studied to determine whether the toxic effects of the combustion products from materials can be explained by the toxicological interactions (as indicated by lethality) of the primary fire gases or if minor, more obscure gases need to be considered. LC50 values for Fischer-344 rats have been calculated for the individual gases, carbon monoxide (CO), hydrogen cyanide (HCN), or decreased oxygen (O2), for 30-min exposures plus relevant postexposure periods using the NBS Toxicity Test Method. Combination experiments with CO and HCN indicate that they act in an additive manner. Synergistic effects have been found when the animals are exposed to certain combinations of CO and carbon dioxide (CO2). Five percent CO2 raised the threshold for deaths due to hypoxia and decreased the LC50 of HCN. Decreasing the O2 concentration in the presence of various mixtures of the other major fire gases increased the toxicity even further. A comparison of the concentrations of the major combustion products generated from a number of polymeric materials at their LC50 (30-min exposure plus 14-day postexposure) values with the combined pure gas results indicates that, in most cases, the observed toxicity may be explained by the toxicological interactions of the examined primary toxic fire gases. These results provide necessary information for the computer model currently being developed at the Center for Fire Research to predict the toxic hazard that people will experience under various fire scenarios.

Air↗
PubMed1979

Correlation between the growth inhibitory effects, partition coefficients and teratogenic effects of lipophilic acids.

The inhibition of cell duplication by many lipophilic acids was measured in Bacillus subtilis and in the following mammalian cell lines, the human epithelial-type cell lines HeLa, strain R and strain L-132, the human fibroblast cell line VA-13, and the rat glial cell line C. The results were correlated to the partition coefficient and the distribution coefficient (= apparent partition coefficient at pH 7.2) of the compounds, using octanol/water partition coefficients and pKa values either from the literature or measured for this work. For B. subtilis, the logarithm of the inhibitory potency of most compounds increases linearly with the logarithm of the partition coefficient. Exceptional high potencies were observed for compounds that can efficiently delocalize the charge of the negative ion over the whole molecule. Most compounds inhibit tissue cultures at least as potently as they inhibit B. subtilis. But some compounds are significantly more potent in tissue cultures than would have been expected from the B. subtilis data; such compounds (analgesics/antipyretics, anti-inflammatory compounds, butyrate, norepinephrine) presumably inhibits mammalian cells by specific reactions with certain cell components. However, most compounds inhibit the different cell lines to a similar degree, indicating no cellular specificity; exceptions to this rule are chlorambucil, chlortetracycline and dexamethasone. Many of the lipophilic acids that are potent inhibitors of mammalian cell replication are also teratogenic. Exceptional compounds may not reach the embryo. We propose that a number of other lipophilic acids that are potenta inhibitors and to which humans are frequently exposed should be tested for their teratogenic effect.

Animals↗
PubMed1978

Cell binding and growth inhibition by hexachlorophene of decanoate and their reversibility.

More than 80% of the hexachlorophene added to a Bacillus subtilis culture binds to the cells. Complete growth inhibition requires 6 x 10(5) molecules bound per cell. In contrast, more than 99% decanoate remains in solution and 3.8 x 10(7) molecules bound per cell are needed to inhibit growth. Centrifugation and resuspension of cells in growth medium removes only decanoate, whereas the addition of 1% bovine serum albumin to the growth medium removes both inhibitors from their binding sites on the cells. The addition of untreated cells to a hexachlorophene-treated culture enables the hexachlorophene molecules to redistribute among all the cells with the result that the inhibited cells can resume growth.

Bacillus subtilis↗
PubMed1977

Comparison of the effects of two lipophilic acids, hexachlorophene and decanoate, on Bacillus subtilis.

The minimal growth-inhibitory amount of either hexachlorophene (HCP) or decanoate stopped growth, respiration, adenosine 5'-triphosphate synthesis, and amino acid transport of Bacillus subtilis in a culture containing amino acids and citrate as carbon sources. The electron transport system was not affected by this dose. Addition of 27.8 mM glucose or 10 mM malate to an inhibited culture did not reverse the binding of HCP or decanoate to the cells, but it allowed resumption of growth, respiration, and adenosine 5'-triphosphate synthesis, as the glucose or malate then supplied the needed carbon. The addition of glucose or malate did not reverse amino acid transport inhibition caused by decanoate, but it did reverse that due to HCP. However, if the dose of HCP was raised in the presence of glucose or malate, only growth and amino acid transport were affected; this indicates that both HCP and decanoate act at their minimal growth inhibitory doses by inhibiting substrate transport. As active transport of amino acids and ketoacids depends on the proton gradient and the membrane potential of the cells, we conclude that the primary effect of these lipophilic acids is the destruction of the proton-motive force.

Adenosine Triphosphate↗