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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 433 records · Page 24Linked to original sources
PubMed1986

Pregnancy in sickle cell disease.

Risks associated with pregnancy for mothers with sickle cell disease and their infants have decreased markedly during the last decade. Among 79 women with sickle cell anemia (156 pregnancies), maternal death decreased from 4.1% before 1972 to 1.7% after 1972; their infants' fetal and perinatal death rates decreased from 52.7 to 22.7% (P less than .05), and from 33.3 to 27.3% among infants of women with sickle hemoglobin C disease. There has been a significant improvement in birth weight specific mortality and an increase in number of weeks' gestation from 34.7 to 37.4 (P less than .05). A higher percentage of sickle hemoglobin C disease mothers completed their pregnancies with no complications (43%) when compared with sickle cell anemia mothers (21%), thus identifying a subset of women for whom pregnancy does not represent an increased risk. These results are attributed to improvements in state-of-the-art medical, obstetric, and perinatal care.

Adult↗
PubMed1986

SAG-M blood.

Explore the source record for details and available documents.

Aged↗
PubMed1986

Comparison of ramp and stepwise incremental pacing in assessment of antegrade and retrograde conduction.

Conventional assessment of antegrade (AV) and retrograde (VA) conduction involves stepwise increments in pacing rates until block in conduction is observed. This study was designed to establish the comparative characteristics of ramp pacing, in which the rate is continuously and smoothly incremented until block occurs. Two hundred and ten patients participated in portions of this study. Stepwise pacing was performed in 10 beat/minute steps, with the rate held for at least 15 seconds at each step; if marked prolongation or variability in conduction was observed, the rate was held constant for up to 60 seconds to allow for accommodation. With ramp pacing, the rate was gradually increased at a steady 2-4 beats/minute/second. Whenever possible, both stepwise and ramp pacing were performed for assessment of both antegrade and retrograde conduction. All patients had conducted sinus rhythm as their baseline mechanism. Antegrade conduction was similar using incremental stepwise and ramp pacing. The AH interval at a cycle length (CL) of 500 ms, the maximum AH increment, the cycle length at AV block were all remarkably similar (p = NS). Assessment of retrograde conduction produced similar results, with insignificant differences between maximum conducted VA intervals, and cycle length at VA block using the two pacing techniques. Ramp pacing provides a useful and rapid alternative to conventional stepwise incremental pacing in the assessment of antegrade and retrograde conduction in patients using both normal and accessory pathways. Ramp pacing was better tolerated, and some correlations between antegrade and retrograde conduction were stronger with the ramp pacing technique.

Atrioventricular Node↗
PubMed1986

Rapid assay for screening and characterizing microorganisms for the ability to degrade polychlorinated biphenyls.

We designed a rapid assay that assesses the polychlorinated biphenyl (PCB)-degradative competence and congener specificity of aerobic microorganisms, identifies strains capable of degrading highly chlorinated biphenyls, and distinguishes among those that degrade PCBs by alternative pathways. Prior attempts to assay PCB-degradative competence by measuring disappearance of Aroclors (commercial PCB mixtures) have frequently produced false-positive findings because of volatilization, adsorption, or absorption losses. Furthermore, these assays have generally left the chemical nature of the competence obscure because of incomplete gas chromatographic resolution and uncertain identification of Aroclor peaks. We avoided these problems by using defined mixtures of PCB congeners and by adopting incubation and extraction methods that prevent physical loss of PCBs. Our assay mixtures include PCB congeners ranging from dichloro- to hexachlorobiphenyls and representing various structural classes, e.g., congeners chlorinated on a single ring (2,3-dichlorobiphenyl), blocked at 2,3 sites (2,5,2'5'-tetrachlorobiphenyl), blocked at 3,4 sites (4,4'-dichlorobiphenyl), and lacking adjacent unchlorinated sites (2,4,5,2',4',5'-hexachlorobiphenyl). The PCB-degrative ability of microorganisms is assessed by packed-column gas chromatographic analysis of these defined congener mixtures following 24-h incubation with resting cells. When tested with 25 environmental isolates, this assay revealed a broad range of PCB-degradative competence, highlighted differences in congener specificity and in the extent of degradation of individual congeners, predicted degradative competence on commercial PCBs, and (iv) identified strains with superior PCB-degradative ability.

Alcaligenes↗
PubMed1986

Dietary calcium and blood pressure in National Health and Nutrition Examination Surveys I and II.

It has recently been reported that a low intake of calcium may be a risk factor for hypertension. In view of the contradictory results, even when the same survey data base has been used by different researchers, an in-depth analysis was undertaken of the data provided by the two cycles of the National Health and Nutrition Examination Survey (NHANES). Both surveys, conducted in consecutive 4-year intervals during the 1970s, were designed to examine representative samples of the U.S. civilian noninstitutionalized population. The overall descriptive findings in relation to mean blood pressure and calcium intake were virtually identical in the two surveys. Based on "quantile" analysis, neither mean levels of blood pressure nor the prevalence of hypertension was related to calcium intake. Only among black men in NHANES I was a relationship between calcium intake and blood pressure noted. This finding was not apparent among black men in NHANES II or among any of the other sex-race groups in either survey. We conclude that the data of NHANES I and II do not show an association between low calcium intake and blood pressure.

Adult↗
PubMed1986

Relation of protein synthesis to plasma and cell amino acids in neonates.

We hypothesized that more rapidly growing preterm infants would have higher rates of protein synthesis than term infants, and that protein synthesis would be more closely related to intracellular than plasma levels of amino acids. Neutrophils, used as a cell model, were isolated from 1-3 ml blood of 63 infants 27-44 wk postconceptual age. Protein synthesis (3H-leucine incorporation, pmol/h/mg DNA), and 19 amino acids in the leukocytes (nmol/mg DNA) and plasma (nmol/ml) were quantified. Protein synthesis was related inversely to birth weight and gestational age, i.e. the smaller and more preterm the infant the higher the rate of protein synthesis. Multiple regression analysis limited to six steps indicated that some plasma amino acids (Val, Ile, Phe, Asp, Ala, Tau) accounted for a significant (p = 0.03), but relatively small, proportion, 23%, of the variance in protein synthesis. A greater proportion of the variance in protein synthesis was explained by a set of six intracellular amino acids (Leu, Met, Tyr, Gly, Ala, Tau), with R2 = 36%, p = 0.001. Further, multiple regression identified specific combinations of six plasma amino acids which best explained ("predicted") the levels of each intracellular amino acid predictor of protein synthesis (R2 = 0.4-0.5, p less than 0.001-0.0001). Activities of some rate-limiting glycolytic enzymes, pyruvate kinase and phosphofructokinase, were correlated with protein synthesis in the leukocytes (p = 0.036, and 0.002, respectively). Phosphofructokinase, the major regulating enzyme in glycolysis, also was negatively correlated with birth weight and gestational age.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1986

Treatment of soft tissue sarcoma with fibroblast interferon (beta-interferon): an American Cancer Society/Illinois Cancer Council Study.

Twenty patients with soft tissue sarcoma were treated with iv human fibroblast interferon (beta-interferon). Each cycle of treatment involved 5 X 10(6) units over 10 minutes, then 5 X 10(6) units iv over 3 hours daily X 10 with cycles repeated every 20 days X 3. Maintenance therapy was given twice weekly if disease was stable or responsive after three therapy periods. One patient had a partial response to treatment and six patients experienced stable disease for variable periods of time. Toxicity (fever, fatigue, leukopenia, hepatic enzyme elevations) was moderate and tolerable; therapy (except in one case of profound granulocytopenia) was neither interrupted nor discontinued because of toxicity. We conclude that beta-interferon in the dose and schedule used has limited value for soft tissue sarcoma.

Adult↗
PubMed1985

Hydralazine: a potent inhibitor of aldehyde oxidase activity in vitro and in vivo.

The interaction of the vasodilator, hydralazine, with the molybdenum hydroxylases, aldehyde oxidase and xanthine oxidase has been investigated. A potent progressive inhibition of rabbit liver aldehyde oxidase, in the presence of substrate, by low concentrations of hydralazine (0.1-1 microM) was observed in vitro but no effect was seen with bovine milk xanthine oxidase. This activity was mirrored in vivo when levels of aldehyde oxidase were significantly decreased in rabbits administered hydralazine (10 mg/kg/day for seven days) whereas hepatic xanthine oxidase activity was unaltered by hydralazine treatment. Various metabolites of hydralazine were synthesized but found to be devoid of in vitro inhibitory activity. Aldehyde oxidase prepared from either guinea pig or baboon liver was inhibited in a similar way to that of rabbit liver.

Aldehyde Oxidase↗
PubMed1985

Laparoscopy or scanning in oesophageal and gastric carcinoma?

A prospective study was undertaken of the accuracy in diagnosing intra-abdominal metastatic disease of the liver by scintigraphy, ultrasound scanning and laparoscopy. The effect of laparoscopy on management was also studied. Fifty patients were studied: 23 oesophageal carcinoma, 14 gastric carcinoma and 13 with suspected intra-abdominal metastatic spread. Accuracy was determined by laparoscopic biopsy, laparotomy and autopsy. The accuracy was 72 per cent for scintigraphy, 75 per cent for ultrasound and 96 per cent for laparoscopy (with 10 per cent failed ultrasound due to intra-abdominal gas). There was no morbidity or mortality associated with laparoscopy, with one failure due to adhesions. Thirteen patients without hepatic metastases had nodal and/or peritoneal spread diagnosed only by laparoscopy. Laparotomy was avoided in 58 per cent, and 74 per cent died in the 18 month follow-up period. Laparoscopy can obviate the need for laparotomy in inoperable cases of oesophageal carcinoma and allow better planning for potentially curable surgery. In gastric carcinoma the value of laparoscopy is doubtful as a high percentage require at least palliative surgery.

Abdominal Neoplasms↗
PubMed1985

Evaluation of the prone position in digital subtraction angiography of the kidneys.

In visualizing the kidneys and renal arteries, the digital subtraction angiography (DSA) image is degraded by peristalsis and overlying bowel gas. In 25 patients we evaluated the efficacy of the prone position to counter these technical difficulties and found that the prone position offers visualization superior to the supine, especially in obese and uncooperative patients and those with abundant bowel gas. We advocate that prone imaging be included routinely in renal DSA.

Adult↗
PubMed1985

Bulimia: disturbed patterns of solitude.

This research suggests that daily solitude has a central role in bulimia. A sample of 15 bulimic patients and 24 normal controls carried electronic pagers for one week and filled out self-reports on their experience in response to randomly timed signals. The bulimics reported the lowest mood states when alone at home, the context in which their symptomatic behavior usually takes place. Further, those who reported the worst experiences in this context were the one's showing the most severe behavioral and affective manifestations of the disorder.

Adult↗
PubMed1985

Controlled comparison of radio wave regional hyperthermia and peritoneal lavage rewarming after immersion hypothermia.

Anesthetized random source dogs were cooled by ice-water immersion to a stable core temperature of 25 degrees C and subsequently rewarmed with normal saline peritoneal lavage (43 degrees C, 175 ml/kg/hr) or radio frequency electromagnetic-induced regional hyperthermia (4-6 watts/kg). The mean time required for core rewarming to 30 degrees C was 183 +/- 79 minutes for lavage and 58 +/- 13 minutes for radio wave therapy (p less than 0.01). There was no evidence of tissue damage with either modality. These data suggest radio wave regional hyperthermia is superior to peritoneal lavage for core rewarming of rapidly induced immersion hypothermia.

Animals↗
PubMed1985

Family characteristics of 105 patients with bulimia.

The authors compared 105 patients who met DSM-III criteria for bulimia with 86 control subjects on measures of family environment and presence of eating disorders. Bulimic patients' perceptions of their families included low cohesiveness, a lack of emphasis on independent and assertive behavior, and a high level of conflict coupled with a low emphasis on open expression of feelings. Families of bulimic subjects had achievement expectations comparable to those of control families, but the former placed less emphasis on intellectual and recreational activities. The high disorganization of the families of bulimic subjects was associated with severity of symptoms.

Achievement↗
PubMed1985

Brush cytology for the early detection of esophageal carcinoma among patients with upper aerodigestive malignancies.

The incidence of associated esophageal carcinoma (EC) among patients with upper aerodigestive tract malignancies is high. Esophageal brush cytology, as developed and evaluated as a screening device for early detection of EC among villagers of northeastern Iran, was employed to examine 56 clinic patients with known tumors of the upper aerodigestive tract on 106 occasions. Two asymptomatic EC were detected and are presented. The procedure was also used as an adjunct to endoscopy in order to monitor the response of tumors under treatment. Sensitivity of 40% and specificity of 90% were found and could be improved with more judicious application of the procedure. The use of this simple test for early detection of EC among this high risk subset of clinic patients is recommended.

Aged↗