The effects of configuration on the stiffness parameters of half-round cast clasps.
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Denture Design↗
Biomedical subjects
D L Johnson
Publications and source records attributed to D L Johnson.
Canine urinary tract infections: a comparison of in vitro antimicrobial susceptibility test results and response to oral therapy with ampicillin or with trimethoprim-sulfa.
In vitro susceptibility testing correctly predicted the outcome of ampicillin therapy in all 56 urinary tract infections (UTI) caused by coagulase-positive staphylococci (Staphylococcus aureus and S intermedius), in all 26 UTI caused by Proteus mirabilis, in 38 of 44 UTI caused by Escherichia coli, in 29 of 31 UTI caused by Streptococcus spp, in 8 of 10 UTI caused by Klebsiella pneumoniae, and in 16 of 20 UTI caused by other bacterial species. Thus, 173 of 187 (92.5%) isolates responded to ampicillin therapy in a manner predicted by in vitro susceptibility test results. In vitro susceptibility testing correctly predicted the outcome of therapy with trimethoprim-sulfa in 119 of 138 UTI caused by Escherichia coli, in 33 of 45 UTI caused by Klebsiella pneumoniae, in 38 of 43 UTI caused by Proteus mirabilis, in 21 of 25 UTI caused by Streptococcus spp, in 9 of 11 UTI caused by coagulase-positive staphylococci, and in 19 of 21 UTI caused by other bacterial species. Thus, 239 of 283 (84%) isolates responded to trimethoprim-sulfa therapy in a manner predicted by in vitro susceptibility test results.
Ampicillin↗
Comparison of 99mTc-N-pyridoxyl-5-methyltryptophan and 99mTc-N-(3-bromo-2,4,6-trimethylacetanilide)-iminodiace tate as hepatobiliary radiopharmaceuticals in rats.
99mTc-N-(3-bromo-2,4,6-trimethylacetanilide)iminodiacetat e (I) and 99mTc-N-pyridoxyl-5-methyl-tryptophan (II) have been described as having optimal properties as hepatobiliary radiopharmaceuticals. This study compared specificity for hepatobiliary excretion, blood disappearance, rates of biliary appearance, and pharmacokinetic parameters including hepatic clearance, volumes of distribution, and mean residence times in normal and sulfobromophthalein-treated rats. The specificity of I was higher as indicated by 94% in the bile at 90 min compared to 91% for II in normal rats and a urine excretion of 0.3% for I compared with 1.9% for II. In sulfobromophthalein-treated animals, urine excretion increases were only to 0.5 and 3.0% for I and II, respectively. In control rats, blood disappearance was similar for both I and II, but II disappeared faster in treated animals. The clearance of II was 70 mL/min/kg in normal and 47 mL/min/kg in treated rats; clearance of I was 51 and 30 mL/min/kg in normal and treated rats, respectively. Volumes of distribution were larger for II. Compound I was superior in specificity while II was superior in clearance and excretion kinetics.
Aniline Compounds↗
Clinical evaluation of Tc-99m N,N'-bis(mercaptoacetyl)-2,3-diaminopropanoate as a replacement for I-131 hippurate: concise communication.
A clinical comparison of Tc-99m N,N'-bis( mercaptoacetyl )-2,3- diaminopropanoate (Component A) (Tc-99m CO2-DADS-A) and I-131 hippurate was conducted in a series of five normal volunteers and 18 patients. Each subject was studied in one session with Tc-99m CO2-DADS-A and I-131-hippurate; digital and analog images were recorded for 30 min and after voiding. In the normal volunteers, digital images with Tc-99m CO2-DADS-A gave a kidney-to-background ratio at 3 min that was greater relative to I-131 hippurate, a leading-edge parenchymal transit time that was similar to I-131 hippurate, and a percent injected dose in the urine at 30 min that was slightly less than I-131 hippurate (p less than 0.05). In patients (serum creatinine 1.0 to 14.3 mg/dl), decreasing renal function impaired excretion of Tc-99m CO2-DADS-A more than that of I-131 hippurate (p less than 0.01). In analog images, Tc-99m CO2-DADS-A always gave superior spatial resolution. No evidence of hepatobiliary excretion was detected with either radiopharmaceutical. We conclude that Tc-99m CO2-DADS-A and similar compounds should be pursued as possible replacements for I-131 hippurate.
Alanine↗
Phorbol myristate acetate induction of lymphotoxins from continuous human B lymphoid cell lines in vitro.
The phorbol ester 4 beta-phorbol 12-myristate 13-acetate (PMA) was studied for its ability to induce increased lymphotoxin (LT) production from a number of continuous human B lymphoblastoid cell lines that spontaneously release low levels of LT in vitro. A 5-20-fold increase in LT production was seen when all seven of these cell lines were cocultured with 20 ng/ml PMA for 72 h under serum-free conditions in 0.1% lactalbumin hydrolysate. One cell line, GM3104A, was cloned and repeatedly selected to obtain a high-level LT producer in the presence of PMA. This subline, termed IR 3.4, spontaneously released the alpha-LT molecular weight (MW) class; however, upon PMA stimulation it released high levels of alpha and an unrelated beta-LT MW class form. The increased amounts of LT released in the presence of PMA by IR 3.4 lymphoid cells provides a new method for the production of large amounts of alpha-LT for purification from a single cell source for biochemical and functional studies, and indicates that the type of induction signal may influence the type of LT released.
Antibodies↗
In vitro susceptibilities of canine urinary bacteria to selected antimicrobial agents.
Antimicrobial susceptibility tests were conducted on bacteria that were isolated from urine specimens collected by antepubic cystocentesis from dogs with urinary tract infections. Antimicrobics to which greater than or equal to 90% of these urinary bacteria were susceptible in vitro included trimethoprim-sulfamethoxazole (TMP-SMZ), nitrofurantoin, cephalexin, nalidixic acid, and gentamicin for isolates of Escherichia coli; ampicillin, TMP-SMZ, cephalexin, nalidixic acid, and gentamicin for isolates of Proteus mirabilis; ampicillin chloramphenicol, TMP-SMZ, nitrofurantoin, cephalexin, kanamycin, and gentamicin for isolates of coagulase-positive staphylococci; cephalexin, nalidixic acid, and gentamicin for isolates of Klebsiella pneumoniae; ampicillin, TMP-SMZ, and gentamicin for isolates of Streptococcus faecalis, Str faecium, and Str zymogenes; ampicillin, chloramphenicol, TMP-SMZ, and gentamicin for isolates of Str viridans; and ampicillin, chloramphenicol, TMP-SMZ, nitrofurantoin, cephalexin, kanamycin, and gentamicin for isolates of Str canis. No antimicrobial agent tested was effective in vitro at the 90% level for isolates of Pseudomonas aeruginosa, but gentamicin was closest, at 89%.
Animals↗
Canine prostatic fluid: techniques of collection, quantitative bacterial culture, and interpretation of results.
Specimens of prostatic fluid were collected by ejaculation from 104 dogs after collection of a specimen of urethral contents and after collection of a urine specimen by antepubic cystocentesis. For purposes of data analysis, results of bacterial culture of the specimens were grouped according to individual colony counts in each specimen group (ie, urine, urethra, prostatic fluid). For purposes of this study, prostatic infection was defined as greater than or equal to 2 log10 of one or more bacterial species in prostatic fluid over the number of colonies of the same species in the paired urethral specimens.
Animals↗
Results of the Canadian Anaesthetists' Society opinion survey on anaesthetic equipment.
Design shortcomings in carbon dioxide absorber bypasses and conical connectors in breathing circuits have been implicated in a number of fatal anaesthesia mishaps. In order to obtain users' views on the risks and benefits of these devices, a questionnaire was sent to 1,950 members of the Canadian Anaesthetists' Society. This paper presents a summary of the 313 responses received. Respondents were equally divided on whether the advantages of a CO2 absorber bypass outweigh the risks of accidental misuse. However, 53 per cent felt the bypass should not be removed from the absorber and 79 per cent favoured clearer labelling of the bypass setting. Accidental disconnections of conical fittings are daily occurrences. The most frequent site is the tracheal tube connector. Sixty-eight per cent of respondents use some method of securing the connectors, in most cases by taping them. The commonest reason given for not using commercial locking devices was that they are not available. Eighty-seven per cent of respondents use disconnect alarms when ventilating a patient.
Anesthesiology↗
Safety of anaesthesia breathing circuit connectors.
Conical connectors used in anaesthesia breathing circuits are prone to accidental disconnections. We tested 291 connectors of 15 and 22 mm size and found that most did not comply with dimensional requirements in voluntary standards such as those issued by the Canadian Standards Association (CSA) and the American National Standards Institute (ANSI). However, measurements of disconnecting force showed no strong correlation with dimensional accuracy as determined by the standard gauge tests. When wrung together, metal-to-metal or plastic-to-plastic joints were considerably stronger than metal-to-plastic joints. Wrung joints were much stronger than connections made with a straight push, which showed no marked dependence on the type of material. Our results indicate that improved compliance with dimensional standards as determined by existing gauge tests will not improve connector performance. Rather, what is needed is a performance standard based on practical criteria. Under such a standard, some materials may prove unsuitable for friction-fit connections.
Anesthesiology↗
Purification to electrophoretic homogeneity of human alpha lymphotoxin from a cloned continuous lymphoblastoid cell line IR 3.4.
The 70-90,000 molecular weight (MW) alpha (alpha) component of the human lymphotoxin (LT) system has been purified to electrophoretic homogeneity. The alpha LT containing supernatants were obtained from a phorbol myristate (PMA) stimulated cloned continuous human B lymphoblastoid cell line IR 3.4. Supernatants were subjected to a biochemical separation scheme that consisted of chromatography on control pore glass beads, DEAE ion-exchange chromatography, lentil-lectin affinity chromatography, and electrophoresis on 7% native preparative polyacrylamide gels. The specific activity of the alpha LT in the final fractions was from 10(7) to 5 X 10(7) units of LT activity/mg protein. Approximately 3 to 5% of the initial alpha LT was recovered in the final fractions and a purification factor of 25,000 to 30,000 fold was required to achieve homogeneity. The alpha LT preparation from preparative PAGE exhibited concident migration of bioactivity and radioactivity on 5 and 7% native PAGE tube gels. Only a single protein peak was observed when the radiolabeled alpha LT was subjected to a two-dimensional SDS-reducing slab gel.
B-Lymphocytes↗
Hidden electrophoretic variation at the xanthine dehydrogenase locus in a natural population of Drosophila melanogaster.
Sixty-two isochromosomal lines of D. melanogaster were screened for cryptic electrophoretic variation at the xanthine dehydrogenase (XDH) locus. Sequential polyacrylamide vertical slab gel electrophoresis was performed using four electrophoretic criteria. A total of 15 classes of electromorphs were revealed. D. melanogaster appears to exhibit as much polymorphism at this locus as other extensively studied Drosophila species.--No evidence for loci on the X or second chromosomes which modified XDH mobility was found. Six of the electromorphs were mapped to the Xdh (ry) structural locus. Eight of the remaining nine classes exhibited mobility variation consistent with structural variation at the Xdh locus. The final class exhibited aberrant patterns and is under further study.
Animals↗
T3 may be a better agent than T4 in the critically ill hypothyroid patient: evaluation of transport across the blood-brain barrier in a primate model.
Thyroid hormone transport across the blood brain barrier in hypothyroid patients is clinically important yet poorly understood. To study this question, 200 micrograms of thyroxine (T4), 100 micrograms of 3,5,3'-triiodothyronine (T3) and 100 micrograms of 3,3',5'-triiodothyronine (reverse T3) were administered separately to 3 baboons, first iv and at a later date intrathecally (IT). Six animals were used. Three received the iv injections and three received the IT injections. In each of the 18 experiments, cerebrospinal fluid (CSF) and serum specimens were collected serially for 6 h after injection. Mean maximal elevations from baseline in CSF iodothyronine levels were 100 +/- 10 ng/dl after iv T4, 3921 +/- 293 ng/dl after iv T3 and 31 +/- 17 ng/dl after iv reverse T3. When given IT in the same dosages, the mean maximal increases in serum iodothyronine concentrations were: 1670 +/- 600 ng/dl for T4, 806 +/- 405 ng/dl for T3, and 210 +/- 43 ng/dl for reverse T3. In every animal studied, rapid bidirectional transfer of T3 from serum to CSF and CSF to serum occurred, whereas iv T4 resulted in delayed minimal increments in CSF T4 concentration. Isotopic experiments were also performed and the results analyzed using a kinetic model. When 125I-T3 was given iv, the equilibrium point in CSF was observed within 90 min with 1.7% of the administered dose/L able to be counted in CSF at any moment in time. When labeled T4 was given iv, only 0.6% of the administered dose/L was counted in CSF and the equilibrium point was not reached until 360 min. These data suggest: (a) T4, T3, and reverse T3 are all capable of bidirectional transfer across the blood brain barrier, (b) T3 may be a better agent than T4 in treating patients with myxedema coma because T3 crosses more rapidly and more completely from serum to CSF.
Animals↗
Crescentic glomerulonephritis complicating idiopathic membranous glomerulonephropathy.
We describe the course of a patient with multiple rectal abscesses and progressive renal dysfunction. A renal biopsy demonstrated a membranous glomerulopathy associated with extensive crescent formation. No underlying cause for the glomerulonephritis could be identified and, specifically, the anti-GBM antibody present in other similar cases was not found. There appears to be a subset of patients with membranous glomerulopathy in whom crescents develop with rapid loss of renal function. Anti-GBM antibody is not necessary in the pathogenesis of this lesion.
Abscess↗
The effect of single plane curvature on half-round cast clasps.
The quality of retention produced by a half-round cast clasp is affected by its curvature in the plane of its flat side. Uncurved clasps and those that curve 90 degrees, 180 degrees, and 270 degrees become progressively stiffer. Conversely, as the radius of the curvature increases, so does the flexibility of the clasp.
Denture Design↗
Polarization-corrosion behavior of commercial gold- and silver-base casting alloys in Fusayama solution.
Based on polarization measurements, high Au alloys are highly corrosion-resistant and exhibit the lowest corrosion rates; intermediate Au, Ag, and Pd alloys with Cu are passive but exhibit higher corrosion rates. Twenty weight percent (w/o) In-Ag alloys exhibit active corrosion behavior at potentials only 100 mV noble to the corrosion potential.
Corrosion↗
Part A or Part B? How TEFRA will change hospital/physician relationships.
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Contract Services↗
Postoperative low cardiac output in infancy.
PLCO can be a devastating and fatal complication after open-heart surgery in infants. Knowledge of the risk factors for the development of PLCO can assist the critical care nurse in anticipating, recognizing, and participating in the treatment of infants who develop this syndrome. An understanding of the causes of PLCO and their relationship to heart rate, preload, afterload, and contractility can help the nurse to predict and interpret its development in her patient. This knowledge can also assist the nurse in differentiating the problem based on her clinical assessments and hemodynamic data. Last, a comprehension of the causes and clinical picture of PLCO will increase the nurse's understanding of the rationale and timing of interventions for PLCO and will equip her to evaluate the effectiveness of those interventions.
Cardiac Output, Low↗
Automated scanning electron microscopic characterization of particulate inclusions in biological tissues.
Rapid individual particle characterization by computer assisted scanning electron microscopy and x-ray energy spectroscopy is now routinely available to many analysts. Its potential in the area of biological microanalysis is substantial. This paper details how these procedures work; showing how computers are interfaced to SEM/XES systems and how the resultant data may be processed for feature classification. The advantages and disadvantages of automated image analysis techniques are contrasted. A specific example of biological microanalysis of the calcium-phosphorus rich concretions in the kidney of marine bivalve molluscs is presented. Concretions were isolated by tissue homogenization and density gradient centrifugation. With the aid of discriminant analysis of the object vectors, a classification scheme for these features was developed. The advantage of computer suppression of artifact particles is demonstrated in this analysis. Results showed that individual heavy metals, as opposed to combinations, were associated with the concretions.
Animals↗