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Biomedical subjects

C A Johnson

Publications and source records attributed to C A Johnson.

At least 253 records · Page 14Linked to original sources
PubMed1991

Decreased tumorigenicity of a transplantable rat sarcoma following transfer and expression of an IL-2 cDNA.

The notion that tumour-cell-derived IL-2 might lead to paracrine stimulation of the host anti-tumour response was tested in a transplantable rat sarcoma model. Three HSNLV clones induced to secrete different amounts of human IL-2 following retroviral gene transfer showed reduced tumorigenicity and metastatic potential in athymic (nu/nu) and immunocompetent syngeneic rats which was directly related to the level of IL-2 secretion. In contrast, the tumorigenicity of HSNLV clones secreting a biologically inactive form of IL-2 (IL-2Lys20) was unaltered. T-lymphocyte-mediated rejection of ZipI, the highest IL-2 producer, was demonstrated histologically in hooded rats and infiltrating mononuclear cells were also observed in ZipI tumours growing in athymic rats. Tumours derived from IL-2-secreting HSNLV showed reduced or absent IL-2 secretion in immunocompetent rats, sometimes with associated loss of the IL-2 provirus, but continued to secrete IL-2 in nude rats. The host response to Moloney-helper-virus-infected HSNLV was also examined and the results represent a cautionary note to those undertaking experiments of a similar nature.

Animals↗
PubMed1991

Steady-state and dynamic response properties of the Mandelbaum effect.

The Mandelbaum effect refers to an inadvertent accommodation response to an intervening surface (e.g. a window screen) while attempting to focus a distant object of interest. Previous research has attributed the Mandelbaum effect to a tendency for the accommodation mechanism to preferentially focus the stimulus nearest the dark (resting) focus position. The present study extends this work by examining dynamic accommodation response properties for different distances and stimulus separations. Accommodation measurements of nine young, emmetropic subjects were obtained with an infrared optometer while they viewed superimposed horizontal and vertical square-wave gratings at various dioptric separations. Three subjects demonstrated a strong focussing preference for the target located nearest their dark focus position for all stimulus conditions, while two other subjects showed a similar, but weaker, preference. Conversely, two subjects primarily focussed the nearer of the two targets, and two subjects tended to focus the vertical target (regardless of whether it was near or far, or was closet to the dark focus). For all subjects, accommodation rarely fluctuated from one target to the other, and was seldom focussed midway between the two targets. Our findings indicate that the influence of the dark focus on the Mandelbaum effect varies among individuals, and plays little or no role in some individuals. Thus, accommodation responses to competing stimuli are more complex than previous findings would suggest.

Accommodation, Ocular↗
PubMed1991

Diagnosis and treatment of chronic vaginitis in the bitch.

The diagnosis of chronic vaginitis is made primarily on the basis of the historical and physical finding of a persistent, nonhemorrhagic vulvar discharge. Licking the vulva and pollakiuria are present in some (10%) bitches with vaginitis. The diagnosis can be confirmed with vaginal cytology and vaginoscopy. Treatment for vaginitis in bitches younger than 1 year of age is justifiably conservative, because the majority of such bitches (90%) recover with or without treatment. Chronic vaginitis in bitches older than 1 year of age most often is associated with identifiable abnormalities of the genitalia (35%) or urinary tract (26%). Resolution of the vaginitis is directly related to the resolution of the other abnormalities.

Age Factors↗
PubMed1991

Randomized controlled trial of prophylactic rifampin for peritoneal dialysis-related infections.

Staphylococcal infections are a major cause of catheter infections and peritonitis in peritoneal dialysis patients. Since catheter-related infections are associated with nasal carriage of Staphylococcus aureus in this population, we studied the effect of intermittent rifampin, an antibiotic known to decrease S aureus nasal carriage, on catheter-related infections and peritonitis. We randomly assigned 64 patients to receive either rifampin 300 mg twice daily for 5 days every 3 months or no treatment. The rifampin-treated patients had a significant delay in time to first catheter-related infection (P less than 0.015) and significantly fewer catheter-related infections overall (P less than 0.001). The catheter-related infection rate in rifampin-treated patients was .26 per patient-year versus .93 per patient-year in untreated patients. Multivariate analysis defined baseline colonization of nares or catheter exit-site and prior renal transplant as risk factors for catheter-related infections. There was no significant difference in peritonitis rates between groups, although the trend was for a delayed time to first episodes and fewer episodes in rifampin-treated patients. Adverse effects necessitated withdrawal of rifampin in four patients. We conclude that intermittent rifampin administration is effective in decreasing catheter-related infections in a peritoneal dialysis population.

Adult↗
PubMed1991

Mediating mechanisms in a school-based drug prevention program: first-year effects of the Midwestern Prevention Project.

Describes (a) the effects of a social-influences-based drug prevention program (the Midwestern Prevention Project) on the mediating variables it was designed to change and (b) the process by which the effects on mediating variables changed use of drugs (tobacco, alcohol, and marijuana). Students in 42 middle schools and junior high schools in Kansas City, Missouri, and Kansas City, Kansas, were measured in the fall of 1984 (N = 5,065) and again 1 year later (N = 5,008) after 24 of the schools had been through the program. Compared to students in control schools, students in program schools became less likely to express belief in the positive consequences of drug use, less likely to indicate that they would use such drugs in the future, more likely to report that their friends were less tolerant of drug use, and more likely to believe that they were better able to communicate with their friends about drug or school problems. Change in perceptions of friends' tolerance of drug use was the most substantial mediator of program effects on drug use. There was evidence that intentions to use and beliefs about the positive consequences of use may also mediate program effects on drug use.

Adolescent↗
PubMed1991

The impact of cigarette smoking on headache activity in headache patients.

The present study was designed to explore the relationship between cigarette smoking and headache activity in a sample of patients presenting for treatment. Subjects completed various self-report measures and monitored headache activity four times per day over a 4-week period. Analyses revealed that smokers experienced greater weekly peak headache intensity, and reported higher levels of depression and general physical symptoms. Among smokers, nicotine content of the preferred brand was associated with mean headache index and weekly headache-free days, as well as depression and anxiety scores. Daily smoking rate and pack-year history were related to level of general physical symptoms only. Thus, both smoking status and the nicotine content of the preferred cigarette appear to adversely impact headache activity. Further, smokers who are more anxious or depressed may increase their headache activity via their preference for higher nicotine-content cigarettes. These results are discussed in the context of possible mechanisms underlying these effects, and implications for the clinical management of headache suffers who smoke.

Adolescent↗
PubMed1991

Quality of laboratory performance in testing for human immunodeficiency virus type 1 antibody. Variables associated in multivariate analyses.

In May 1988, the Centers for Disease Control's Model Performance Evaluation Program (Atlanta, Ga) surveyed 1092 laboratories that performed enzyme immunoassays and Western blot tests for human immunodeficiency virus type 1 antibody on mailed plasma samples of known human immunodeficiency virus type 1 antibody reactivity and that described their laboratory characteristics and testing practices. The study objective was to evaluate the quality of laboratory performance in testing for human immunodeficiency virus type 1 antibody. After identifying relevant variables in univariate analyses, multivariate analyses were performed using stepwise logistic models. Human immunodeficiency virus type 1 antibody test performance was independently associated with analytic variables such as commercial test kit used and with nonanalytic variables such as experience, training, and degree requirements of laboratory personnel. These results validate the importance of nonanalytic variables to the quality of outcomes in laboratory testing.

AIDS Serodiagnosis↗
PubMed1991

Clinical significance of hyperkeratosis on otherwise normal Papanicolaou smears.

BACKGROUND: Although hyperkeratosis is a common cytological finding on Papanicolaou smear, its clinical significance is unclear. METHODS: A profile of patients with hyperkeratosis was constructed by comparing them to an age-matched control population having normal Papanicolaou smears. The clinical significance of hyperkeratosis was evaluated and appropriate follow-up studies were recommended. RESULTS: Of 2198 Papanicolaou smears done in the University of Kansas Family Practice Department between October 1, 1988, and October 31, 1989, there were 184 diagnoses of hyperkeratosis from smears on which no other pathological findings were noted. Charts of 183 of these patients with hyperkeratosis were reviewed and compared with an age-matched control population having normal Papanicolaou smears. Patients with hyperkeratosis had a statistically higher incidence of infections with Gardnerella vaginalis, but a lower incidence of infections with Chlamydia trachomatis. Diaphragm use was more prevalent in the group with hyperkeratosis. The incidence of inflammation on Papanicolaou smear was similar between the two groups. Of the patients with hyperkeratosis, colposcopic examination had been performed on 48% (88 of 183), of which 28% (25 of 88) had evidence of human papillomavirus or dysplasia. CONCLUSIONS: Review of the data obtained suggests that follow-up colposcopy, including endocervical curettage, be performed on all patients with hyperkeratosis in order to screen for accompanying pathological conditions that may necessitate treatment.

Adult↗
PubMed1991

Erythropoietin use in peritoneal dialysis patients.

Erythropoietin (Epo) is currently used less extensively in peritoneal dialysis (PD) patients than in hemodialysis (HD) patients. Early data suggest that Epo is equally effective in PD patients, and that the risk profile is similar. No adverse consequences to the dialysis procedure or peritonitis rates have been consistently noted. It has been suggested that PD patients may require less Epo than their HD counterparts, but this is unproven. Further research on the preferred route of administration and timing of the dosing is necessary.

Anemia↗
PubMed1991

Making sense of dysfunctional uterine bleeding.

Dysfunctional uterine bleeding is abnormal vaginal bleeding originating in the uterus and caused by a hormonal mechanism. Other sources and causes of vaginal bleeding should be considered before the diagnosis is established. Dysfunctional uterine bleeding is diagnosed on the basis of the history and physical examination, supported by other investigations, particularly endometrial sampling. An appropriate management plan can be developed for each patient, depending on the ovulatory state, endometrial thickness and reproductive phase, as well as the quantity and duration of bleeding.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1991

Management of snakebite.

Patients who have been or may have been bitten by a snake should receive prompt and careful clinical and laboratory evaluation. Fang marks, pain and swelling are characteristic of pit viper envenomation. Although no therapy is universally accepted, a number of treatment plans appear to be effective. If envenomation has occurred, intravenous administration of antivenin and/or surgical excision or incision should be carried out without delay. Prompt transferral to a medical facility is the most appropriate first-aid measure. If transportation is unduly delayed, immediate linear incision and suction may be of value.

Antivenins↗
PubMed1990

Primary thyroid lymphomas. A clinicopathological study of 8 cases.

Eight elderly women with primary non-Hodgkin's lymphoma were treated with a combination of surgery, chemotherapy and radiation with excellent outcome. Clinically, the patients presented with thyromegaly and did not have lymphadenopathy or hepatosplenomegaly. On histological examination, the lymphomas resembled diffuse follicle-centre cell tumours. All patients showed extension beyond the thyroid capsule and lympho-epithelial lesions; 3 displayed kappa-light-chain restriction and 2 lambda-monoclonality. Thyroid lymphomas fall into the spectrum of mucosa-associated lymphomas, which have a better prognosis than their equivalent nodal-based counterparts.

Aged↗
PubMed1990

Drug use prevention programs, gender, and ethnicity: evaluation of three seventh-grade Project SMART cohorts.

One-year follow-up data from three seventh-grade cohorts of Project SMART were examined to assess the effects of two social psychology-based programs within each of six subgroups: males, females, Asians, blacks, Hispanics, and whites. The three cohorts (total N = 5,070) were those receiving curriculum or serving as controls as seventh-graders in 1982-1983, 1983-1984, and 1984-1985 school years. The outcome measures used were composite indices based on lifetime and recent use items for cigarettes, alcohol, and marijuana. The major analysis was ANCOVA on classroom means for the composite indices at post-test, using pretest classroom means for the indices as a covariate. The results showed clear prevention effects for females but not for males. Overall prevention effects were strongest for cigarette smoking, but were also evident for alcohol. Significant sex by program interactions, showing differential program effects for males and females, were found for cigarettes and marijuana, but not for alcohol. There was a nonsignificant trend suggesting that the programs were most effective for Asians and least effective for whites.

Adolescent↗