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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 181 records · Page 10Linked to original sources
PubMed1997

Simian foamy virus type 1 (SFV-1) induces apoptosis.

Foamy virus infection causes cytopathology in several cell types from different species. The mechanism of cell killing by foamy viruses is not known. In this report, the mechanism of cell death induced by simian foamy virus type 1 (SFV-1) infection was investigated in fibroblast and lymphoid derived cells lines. Infected L-929 (fibroblast) and Raji (B cell) cells showed chromatin condensation, chromatin cleavage into nucleosome oligomers, and ultrastructural changes consistent with apoptosis. These data suggest that SFV-1 induced apoptotic cell death in different cell lines from different species. The degree of apoptotic cell death in both L-929 and Raji cell lines correlated with increased virus replication. Apoptosis, therefore, is one mechanism by which SFV-1 causes cell death.

Animals↗
PubMed1997

Cementless revision of total hip arthroplasty using the anatomic porous replacement revision prosthesis.

This study reports the results of revision total hip arthroplasty with the Anatomic Porous Replacement Revision Hip System (Intermedics Orthopedics, Austin, TX) to investigate the value of cementless fixation. Sixty-six hips in 65 patients were followed for a mean of 4.7 years in patients with a mean age of 56 years. Thirty-six patients were categorized as Charnley class A, 16 as class B, and 13 as class C. Forty (61%) of the femurs were classified before surgery as having loss of bone distal to the intertrochanteric line. Thirty-two (48%) of the femurs required augmentation with demineralized strut cortical allografts, 5 (8%) required bulk femoral allografts, and 12 hips (18%) required acetabular allografts. Overall, 4 stems (6%) and 2 acetabular components (4%) required further revision surgery. The reason for further revision in 1 stem and both acetabular components was allograft failure. Fifty-six (85%) hips had excellent or good Harris hip scores. Ninety percent of hips had no or slight pain, and 90% allowed patients to walk with no or slight limp. Those hips that had hydroxyapatite coating added to the porous coating had statistically improved Harris hip scores for both pain and limp. Stable fixation was present in 95% of stems. Demineralized strut grafts healed in 30 of 32 hips. Thirty-nine of 44 noncemented revision sockets had no radiolucent lines and there were no loose components. Cementless fixation was effective for these hips.

Acetabulum↗
PubMed1997

Identification of sn-2 acetyl glycerophosphocholines in human keratinocytes.

Evidence is accumulating suggesting that platelet-activating factor plays a role in inflammatory dermatoses. Mass spectrometric methods were used to examine the molecular species of sn-2 acetyl glycerophosphocholines (GPC) synthesized by primary cultures of human neonatal foreskin-derived keratinocytes. Ionophore-stimulated keratinocytes synthesize both 1-alkyl and 1-acyl sn-2 acetyl-GPC, and the relative amounts were as follows: hexadecyl > palmitoyl > octadecyl > stearoyl at the sn-1 position. PAF synthesis in the keratinocyte-derived cell line HaCaT was inhibited by dexamethasone, suggesting that the anti-inflammatory effects of glucocorticosteroids in inflammatory dermatoses might be in part related to the inhibition of the synthesis of mediators such as PAF.

Adrenal Cortex Hormones↗
PubMed1997

Associations of oral contraceptive use with serum lipids and lipoproteins in young women: the Bogalusa Heart Study.

PURPOSE: Cross-sectional and longitudinal associations of serum lipids and lipoproteins with oral contraceptive (OC) use were examined among white and black women aged 18-27 years in 1985-86 and 1988-1991 in the Bogalusa Heart Study, a study of cardiovascular disease in a Southern community. METHODS: Analyses of covariance. RESULTS: In 1985-1986, white OC users had significantly (p < 0.05) higher adjusted mean total and low density lipoprotein (LDL) cholesterols, and lower high density lipoprotein (HDL) cholesterol compared with nonusers; black OC users had higher triglycerides and LDL cholesterol, and lower HDL cholesterol. In 1988-1991, white OC users had higher total cholesterol, triglycerides, and LDL cholesterol, while black OC users had higher triglycerides. OC use was unrelated to mean HDL cholesterol levels in 1988-1991; however, a lower percentage of white OC users than nonusers in 1988-1991 had HDL cholesterol levels < 35 mg/dl. Longitudinally, white OC nonusers at baseline who used OCs at follow-up had significant increases from baseline levels in total cholesterol, triglycerides, and very low density lipoprotein (VLDL) and LDL cholesterols; black women showed an increase only in LDL cholesterol. White women who stopped using OCs by follow-up had a decrease in VLDL and LDL cholesterols, and an increase in HDL cholesterol. White OC users at both exams also had a significant increase in HDL cholesterol, whereas women who began using OCs by follow-up did not. CONCLUSIONS: The unfavorable lipid profile associated with OC use was not apparent upon discontinued use. Lack of an adverse effect of OC use on HDL cholesterol at follow-up may be the result of changing formulations, and requires further examination.

Adolescent↗
PubMed1997

Increased esophageal chemoreceptor sensitivity to acid in patients after successful reversal of Barrett's esophagus.

When compared to patients with erosive esophagitis, patients with Barrett's esophagus have demonstrated reduced chemo- and mechanoreceptor sensitivity to acid infusion and balloon distension, respectively. However, anecdotal clinical experience suggested an increase in symptom perception in patients after successful elimination of Barrett's epithelium, using multipolar electrocoagulation (MPEC) and high-dose proton pump inhibitor (PPI). To determine perception thresholds to acid infusion, we evaluated eight consecutive patients after a series of MPEC treatments resulted in complete elimination of Barrett's mucosa and compared them to 10 age-matched patients with nonreversed Barrett's esophagus and 10 patients with symptomatic, endoscopy-documented erosive esophagitis (Hetzel-Dent grade 2 or greater). Chemosensitivity was determined by a modified acid perfusion test, where acid perception thresholds were quantified by the lag time to initial typical symptom perception, sensory intensity rating, and an acid perfusion sensory score (APSS). While patients after successful elimination of Barrett's esophagus had similar sensory intensity ratings and APSS as patients with erosive esophagitis, the lag times differed significantly between the groups, and both groups had significantly higher sensory intensity ratings and APSS than patients with nonreversed Barrett's esophagus. In conclusion, patients after complete reversal of Barrett's mucosa are unexpectedly as sensitive to acid as symptomatic patients with erosive esophagitis.

Anti-Ulcer Agents↗
PubMed1997

Length of maternal hospital stay for uncomplicated deliveries, 1988-1995: the impact of maternal and hospital characteristics.

OBJECTIVES: To determine the independent association of selected maternal and hospital characteristics with length of maternal hospital stay for uncomplicated vaginal deliveries. METHOD: Linear regression analysis using National Hospital Discharge Survey data from 1988 to 1995. Independent variables were year, maternal age and race, method of payment, and hospital ownership, size, and geographic location. The outcome measure was length of maternal hospital stay for uncomplicated vaginal deliveries. RESULTS: Length of stay was independently associated with year, geographic region, payment method, and hospital size. From 1988 to 1995, the mean length of stay fell from 2.1 to 1.5 days. The rate of decrease was similar for all regions, methods of payment, and hospital size. Women in the West had a shorter mean length of stay (1.5 days) than women in the Northeast (2.2 days). The difference by method of payment was smaller. Length of stay was shortest for women without insurance (1.8 days) and longest for women covered by Blue Cross (2.1 days). Maternal age and race and type of hospital ownership were not independently associated with the length of stay. CONCLUSIONS: Significant variations existed in the length of time women are hospitalized for normal childbirth. These variations are primarily associated with where a woman lives and whether she is insured. Given the current public debate on the impact of shortened hospital stays, these variations need to be explored and their effects on maternal and infant well-being clarified.

Adolescent↗
PubMed1997

The sickle cell hemolytic transfusion reaction syndrome.

BACKGROUND: Patients with sickle cell anemia may develop serious, life-threatening hemolytic transfusion reactions (HTRs). More severe anemia may develop after the HTR than was present before transfusion, which suggests the possibility of an increased rate of hemolysis of autologous red cells. STUDY DESIGN AND METHODS: The signs and symptoms occurring during eight severe HTRs that occurred in five patients with sickle cell anemia were reviewed, as were published reports by other investigators. Calculations of red cell production and destruction incorporating known correction factors for reticulocyte maturation were performed to determine the most probable mechanism for the striking drop in hematocrit observed in several instances. RESULTS: A characteristic constellation of findings was recognized in some severe HTRs in patients with sickle cell anemia. Calculations of daily red cell production and senescence indicated that a marked drop in hematocrit occurs when erythropoiesis is suppressed in a patient with a short red cell life span and that this could account for severe posttransfusion anemia when donor red cells are hemolyzed during an HTR. CONCLUSION: A sickle cell HTR syndrome was defined. A rapid increase in the severity of anemia occurs in patients with sickle cell anemia when all donor red cells are hemolyzed during an HTR and when there is suppression of erythropoiesis, as commonly occurs as a result of transfusion or concomitant illness. Although an increased rate of hemolysis of autologous red cells may also occur, more definitive data are required to document that in these patients.

Adolescent↗
PubMed1997

Both the cyclic AMP response element and the activator protein 2 binding site mediate basal and cyclic AMP-induced transcription from the dominant promoter of the rat alpha 1B-adrenergic receptor gene in DDT1MF-2 cells.

cAMP markedly increases alpha 1B adrenergic receptor (alpha 1B-AR) expression in FRTL-5 and PC C13 rat thyroid cells, DDT1MF-2 smooth muscle cells, primary rat hepatocytes, and K9 rat liver cells. Here, we used DDT1MF-2 cells to evaluate further the mechanisms by which cAMP stimulates alpha 1B-AR expression. Receptor binding assays, Northern blotting, and nuclear run-on analyses demonstrated that forskolin (1 microM) in the presence of isobutylmethylxanthine (0.25 mM) increased alpha 1B-AR numbers, mRNA level, and gene transcription rate by 2.3 +/- 0.2-, 2.5 +/- 0.3-, and 3.5 +/- 0.2-fold over control, respectively. Dibutyryl cAMP (1 mM) plus isobutylmethylxanthine (0.25 mM) also enhanced alpha 1B-AR density by 2.7 +/- 0.1-fold over control. Further experiments demonstrated that the induction of alpha 1B-AR by forskolin requires new protein synthesis and is protein kinase A dependent. In DDT1MF-2 cells transfected with alpha 1B-AR gene P2 promoter/CAT constructs, both forskolin and dibutyryl cAMP significantly increased P2 promoter activity. The P2 promoter region of the rat alpha 1B-AR gene (-813 to -432) contains a cAMP response element (CRE) (-444 to -437) and an AP2 binding site (-647 to -638). Mutations in either one of these elements alone led to a decrease in both basal and cAMP-induced P2 promoter activity. Mutations in both elements caused a further inhibition of basal transcription and a complete block of cAMP-induced P2 promoter activity. Direct binding of purified activator protein 2 (AP2) to the AP2 element in the P2 promoter was reported previously. Gel mobility shift and super-shift assays using liver nuclear extracts from either rat liver or DDT1MF-2 cells demonstrated that the CRE in the alpha 1B-AR gene bound CRE binding protein. These data indicate that both the CRE and the AP2 element in the P2 promoter contribute to basal as well as cAMP-induced transcription of the alpha 1B-AR gene in DDT1MF-2 cells.

Animals↗
PubMed1997

The Child and Adolescent Trial for Cardiovascular Health (CATCH): intervention, implementation, and feasibility for elementary schools in the United States.

The Child and Adolescent Trial for Cardiovascular Health (CATCH) was the largest school-based field trial ever sponsored by the National Institutes of Health. The trial demonstrated positive changes in the school food service and physical education program, as well as in students' cardiovascular health behaviors. Because the CATCH intervention programs were implemented in 56 schools (in four states) that were typical of schools throughout the United States, their reception by schools and degree of implementation provide evidence about their feasibility for schools nationally. Extensive process evaluation data were collected from students, teachers, school food service personnel, and physical education specialists throughout the three school years of the CATCH intervention. Four of the CATCH programs--school food service, physical education, classroom curricula, and home programs--were assessed over the three school years. The process data provide information on participation, dose, fidelity, and compatibility of the CATCH programs in the intervention schools for these programs. High levels of participation, dose, fidelity, and compatibility were observed for the four programs during the 3 school years. CATCH emerges as a model of a feasible multilevel health promotion program to improve eating and exercise behaviors for elementary schools in the United States.

Adolescent↗
PubMed1997

Bare area abscess: imaging findings and potential communication with the mediastinum.

The bare area of the liver is not usually visualized by standard cross-sectional imaging techniques except in patients with ascites or subphrenic collections where this area is spared of fluid. We present a case of an abscess in the bare area of the liver with imaging findings and demonstration of a communication with the mediastinum, not previously described.

Aged↗
PubMed1997

Reduced chemoreceptor sensitivity in patients with Barrett's esophagus may be related to age and not to the presence of Barrett's epithelium.

BACKGROUND: Patients with Barrett's esophagus have demonstrated reduced chemo- and mechanoreceptor sensitivity to acid infusion and balloon distension, respectively. However, Barrett's esophagus is mainly a disease of the elderly, making age the possible underlying mechanism for altered pain perception in this patient population. OBJECTIVES: To determine perception thresholds to acid infusion in elderly (>65 yr) versus younger (< or =50 yr) patients with Barrett's esophagus. METHODS: Twelve elderly and 10 younger patients, matched by length of Barrett's mucosa, were recruited into the study. All patients participated in our Barrett's esophagus surveillance program. The patients were treated with omeprazole 20 to 60 mg/day and were symptom free. Chemosensitivity was determined by a modified acid perfusion test, in which acid perception thresholds were quantified by the lag time to initial typical symptom perception, sensory intensity rating, and an acid perfusion sensory score. RESULTS: Five of the elderly patients with Barrett's esophagus had a negative test, whereas all younger patients with Barrett's esophagus experienced typical symptom perception during acid infusion. Elderly patients with Barrett's esophagus had significantly longer lag time to initial perception, lower acid perfusion sensory score, and sensory intensity rating in comparison with the younger patients. CONCLUSIONS: Reduced chemoreceptor sensitivity to acid perfusion that has previously been demonstrated in patients with Barrett's esophagus may be related to age and not to the presence of Barrett's epithelium.

Adult↗
PubMed1997

Is Barrett's esophagus associated with intestinal metaplasia of the gastric cardia?

OBJECTIVE: Barrett's esophagus has been associated with adenocarcinoma of the esophagogastric junction and gastric cardia. The purpose of this study was to determine whether patients with Barrett's esophagus have a higher prevalence of intestinal metaplasia involving the gastric cardia than those without Barrett's esophagus. METHODS: Two groups of patients were compared for the prevalence of intestinal metaplasia of the gastric cardia. Group 1 included 50 patients with well-defined Barrett's esophagus who were being followed in an endoscopic surveillance program. Group 2 consisted of 104 individuals participating in a separate study identifying the prevalence of cardia intestinal metaplasia in patients undergoing elective upper endoscopy. Both groups had biopsy specimens taken from the gastric cardia. Eleven patients in group 2 were found to have Barrett's esophagus and were excluded from the analysis. Histological evidence of intestinal metaplasia was defined as specialized columnar epithelium containing goblet cells staining with Alcian blue at pH 2.5. RESULTS: The prevalence of cardia intestinal metaplasia in the 50 patients in group 1 (Barrett's esophagus) was 22%, whereas the prevalence in the 93 patients in group 2 (no Barrett's esophagus) was 24%, which was not a statistically significant difference. A significant difference between groups still could not be identified when the results were examined with regard to equal number of biopsy specimens taken. None of the patients in either group had dysplasia identified within the cardia intestinal metaplasia. CONCLUSIONS: Patients with Barrett's esophagus do not have a higher prevalence of intestinal metaplasia of the gastric cardia than those presenting for routine endoscopy. Although intestinal metaplasia of the gastric cardia is a relatively common finding, dysplasia is uncommon. Therefore, we suggest that screening biopsy specimens of the gastric cardia in patients with Barrett's esophagus be limited to study protocols at this time. In addition, we believe that these data raise the question of whether a true association exists between Barrett's esophagus and gastric cardia cancer.

Aged↗
PubMed1996

Influence of depression on cognitive functioning in Fragile X females.

We sought to determine the frequency of a history of major depression in women with Fragile X syndrome. In addition, we attempted to disentangle the cognitive effects of major depression from those of Fragile X syndrome. Thirty-seven mothers of developmentally delayed children (Fragile X syndrome: n = 18; comparison group n = 19), matched for age, educational level, and socioeconomic status, were administered psychiatric and neuropsychological measures. Women with Fragile X syndrome had a higher frequency of lifetime diagnosis of major depressive disorder (78%) than the comparison group (37%). Mild impairment was seen on visuospatial construction and memory tasks in women with Fragile X syndrome, while women with depression showed subtle deficits in several aspects of visuospatial perception and learning. There was no interaction of Fragile X syndrome and depression in their influence on cognition. The results underscore the importance of considering the influence of depression on cognitive performance in studies of genetic disorders.

Adult↗