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Biomedical subjects

L Smith

Publications and source records attributed to L Smith.

At least 649 records · Page 36Linked to original sources
PubMed1977

Karyology of a human colonic carcinoma (GW-39) serially xenografted in hamsters and in nude mice.

A karyological analysis of the G-banded chromosomes of the serially transplantable GW-39 human colonic carcinoma was undertaken. GW-39 cells harvested from hamsters, nude (athymic) mice and cell cultures from 1972 to 1976 revealed a hypodiploid stemline of 45 human chromosomes, with a consistent loss of a 21-chromosome. No apparent alterations of the near-diploid stemline resulted during long-term xenogeneic propagation of this human cancer line.

Animals↗
PubMed1977

Growth properties of mecillinam-resistant bacterial variants in urine.

Resistant variants are often formed when susceptible Enterobacteriaceae are grown in media containing mecillinam. These variants have not yet been detected in patients or identified as a cause of treatment failure in limited clinical trials. Mecillinam-resistant organisms were formed by 5 out of 13 urinary isolates of Enterobacteriaceae incubated in urine containing mecillinam. The mean generation time of these five variants in urine containing therapeutic concentrations of mecillinam was 3.2 times that of normal organisms in antibiotic-free urine. When three of these five resistant variants were subcultured in antibiotic-free urine, the generation time, morphology, and antibiotic susceptibility returned to normal. On antibiotic-free agar medium, all five mecillinam-resistant variants readily reverted to the "susceptible" form and were therefore more likely to be phenotypic rather than genotypic mutants. In a second series of experiments, the flushing effect of the bladder on the clearance of organisms was partly simulated by frequent subculture in urine. Under these conditions, the cell density of cultures of all bacteria remained high during 10 subcultures over 52 h. However, bacterial populations progressively decreased in urine containing mecillinam until none could be detected at 28 h or thereafter. The slow growth rate of mecillinam-resistant variants may explain why detectable numbers of these organisms fail to colonize the urinary tract during treatment. Other factors may reinforce the postulated effect of the reduced growth rate in vivo.

Amdinocillin↗
PubMed1977

Ultrasonographic evaluation of juxtadiaphragmatic masses in children.

The authors suggest that ultrasound be used in the evaluation of juxtadiaphragmatic lesions before resorting to other radiographic methods. This technique gives accurate diagnoses, serves as a guide for further studies, and might obviate more extensive procedures.

Diaphragmatic Eventration↗
PubMed1976

A new, more sensitive tube test for pregnancy evaluated with a selected hospital population.

A new tube test for pregnancy, having a sensitivity of 0.5 I.U. of human chorionic gonadotropin per milliliter, was evaluated, along with two other commercially available kits, in a hospital patient population. Of 586 patients in the study, 302 were in nonobstetric services and many were acutely ill. Approximately one fourth of the women were age 40 or older. The medical records of 66% of the patients were retrieved to obtain information on the drugs administered prior to pregnancy testing. A small number of problems did occur in the pregnancy test procedures. Inconclusive results were recorded for both pregnant and nonpregnant patients and could not be correlated with disease states and/or medications. The importance of a reagent control for tube test procedures is discussed.

Chorionic Gonadotropin↗
PubMed1976

Oxidation and reduction of membrane-bound cytochrome c in Hemophilus parainfluenzae. Reaction with oxygen, hydrogen peroxide and nitrate.

Cytochromes of the a-, b-, c- and d-type become reduced when intact cells of Hemophilus parainfluenzae have become anaerobic following respiration with substrates such as formate or succinate, as shown previously (J. Biol. Chem. (1970) 254, 5096-5100). In the presence of formate after depletion of O2, there is an unusual two-step time course of reduction of the membrane-bound cytochrome c. The proportion of the cytochrome c which is reduced during the second stage is oxidizable by either nitrate or H2O2 and is reduced again when the nitrate or H2O2 have been depleted. We conclude that the observed two-stage reduction of cytochrome c results from the presence of an oxidant, probably H2O2, produced by reaction of formate dehydrogenase with O2. This was shown by the effects of cyanide, catalase and O2. In addition, no evidence for the production of the oxidant is seen when succinate is the substrate oxidized. Although measurements of absorption spectra indicated only one species of cytochrome c, kinetic evidence is presented for some separation of the cytochrome c into more than one electron transport pathway.

Binding Sites↗
PubMed1976

Study on the usefulness of hypertonic culture media.

Specimens from 300 patients were studied using five to nine aerobic and anaerobic culture media, including five that were hypertonic, Groups studied included fever of unknown origin, suspected endocarditis, endocarditis during therapy, bacteremia during therapy, abscess and cellulitis, presumed infectious arthritis, renal transplantation during rejection, collagen disease, sarcoidosis, lymphoma, and colitis. Isolates in hypertonic media were reverted to parent form by agar passage. In only 5% of these selected cases were organisms found in hypertonic, but not conventional, media that appeared on the basis of repeated isolation and/or serological studies to come from the patient. Nine of the 16 appeared to be of major significance. The two groups in which use of highly enriched, hypertonic media seemed most helpful were suspected endocarditis and undefined meningitis with negative cultures using standard media. The most effective of the hypertonic media used was 0.3 M sucrose in brain heart infusion with 20% horse serum. In most instances, the organism grew only in the hypertonic sucrose, and in most cases it appeared in conventional rather than aberrant form. Hypertonic media, especially 0.3 M sucrose, are of substantial helpin a small number of carefully selected cases.

Adolescent↗
PubMed1976

Detection of the velocity of movement of visual stimuli by pigeons?

Nine pigeons were trained to discriminate a moving stimulus from a stationary stimulus. In one experiment, the stimulus was a rotating disc with radial stripes. In a second experiment, the stimulus was a vertically moving film strip with horizontal bars. Several psychophysical procedures were used to determine the minimal detectable velocity of movement. The detection thresholds for most of the pigeons fell in the range of 4.4 to 6.5 millimeters per second, corresponding to a retinal velocity of 4.1 to 6.01 degrees per second. A signal detection analysis of the psychophysical data indicated systematic changes in response bias that were related to the ordinal position of the stimulus velocity in the sequence.

Animals↗
PubMed1976

5-Fluorouracil (5-FU), methyl-CCNU, and vincristine in the treatment of advanced colorectal cancer: phase II study utilizing weekly 5-FU.

We report a phase II trial of 5-fluorouracil (5-FU), methyl-CCNU, and vincristine (FMV) combination chemotherapy in advanced colorectal carcinoma. Ten of 25 patients (40%) achieved an objective tumor regression after treatment with FMV chemotherapy. The main toxicities of FMV were hematologic and gastrointestinal. 5-FU was administered in a weekly rather than a loading-dose schedule which allowed for sensitive adjustment of drug dosages according to hematologic toxicity; only 16% of the patients (four of 25) had a wbc count less than 2000 cells/mm3. FMV is significantly more active than 5-FU alone in the treatment of advanced colorectal cancer; however this regimen does not significantly improve survival in responding patients.

Adult↗