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Biomedical subjects

C A Carlson

Publications and source records attributed to C A Carlson.

At least 19 recordsLinked to original sources
PubMed1992

Allergic reactions to latex among health-care workers.

With the emergence of the acquired immunodeficiency syndrome (AIDS) epidemic and the practice of protecting health-care workers from all body fluids, the use of rubber gloves has increased, as has occupational allergy to latex among health-care workers. During 1991, 49 Mayo Medical Center employees sought assessment and treatment of rhinitis, conjunctivitis, contact urticaria, contact dermatitis, asthma, or eczema thought to be related to exposure to latex. Most of these persons had a history of atopy and worked in areas where rubber gloves were used and changed frequently. Of the 49 subjects, 34 had positive results of skin tests to latex products, and the sera from 19 of 35 persons tested contained increased latex-specific IgE antibodies. Employees with sensitivity to latex (and co-workers in the immediate areas) should use vinyl gloves and should notify their own health-care providers of their sensitization. Changes in job assignment may be necessary for some persons.

Asthma↗
PubMed1991

Anterior cruciate ligament injuries. Evaluation, arthroscopic reconstruction, and rehabilitation.

The advantages of arthroscopic reconstruction of the anterior cruciate ligament tear over arthrotomy are quite obvious: reduced pain and morbidity. Some arthroscopists are performing these procedures on an outpatient basis. The physician can choose from several graft substitutes for anterior cruciate ligament replacement. Autografts consisting of the iliotibial band, semitendinosus, gracilis, and meniscus have been used as grafts. The most common autograft is the bone-patellar tendon-bone, which has been used since 1930 and has been shown to have a tensile strength near that of the anterior cruciate ligament. The state of the art in surgical alternatives for anterior cruciate ligament tears is arthroscopic reconstruction using the midthird of the patellar tendon. Treatment of anterior cruciate ligament injuries requires prompt and adequate evaluation of the laxity of the ligament as well as other structures in the knee, appropriate treatment options offered to the patient with complete descriptions of knee function after each treatment option, and comprehensive rehabilitation program. Patient compliance is an integral part of the success of this procedure. The nurse must include a description of the injury, preoperative testing, surgical intervention, and rehabilitation program when educating the patient. The successful postoperative anterior cruciate ligament rehabilitation program is multifaceted. In general, there must be specific guidelines applied by a physical therapist who has knowledge of the surgical procedure, understands principles of ligament healing, and has the ability to individualize the program as needed. For any level of athlete or active person, there must be achievement of all goals per phase to a high performance level. In addition, there must always be objective measurements to document progress to the physical therapist and physician but, perhaps most importantly, to reassure the patient that normalcy is being restored.

Anterior Cruciate Ligament↗
PubMed1990

Antihypertensive effects of a new sustained-release formulation of nifedipine.

The blood pressure response to a new sustained-release formulation of nifedipine was evaluated in an 8-week, double-blind, placebo-controlled study. Twenty-nine patients with mild essential hypertension were randomized to receive placebo (N = 9), 30 mg nifedipine (N = 10), or 60 mg nifedipine (N = 10). During treatment, 30-mg and 60-mg doses of nifedipine administered once daily decreased office blood pressures from 137/98 +/- 8/2 mm Hg and 141/98 +/- 15/2 mm Hg at baseline, respectively, to 126/89 +/- 9/7 mm Hg and 126/86 +/- 6/7 mm Hg (P less than .005). Noninvasive automatic ambulatory blood pressure monitoring demonstrated a marginally significant (P less than .10) reduction in the mean 24-hour blood pressure of 2/6 +/- 8/8 mm Hg and 5/6 +/- 9/9 mm Hg for patients taking 30 mg and 60 mg nifedipine once daily, respectively. Diastolic blood pressure load (the percentage of ambulatory diastolic blood pressure readings greater than 90 mm Hg) during 24 hours was decreased by 41% and 35%, with 30 mg and 60 mg nifedipine administered once daily, respectively. No significant dose response to nifedipine at these dose levels was observed. Although the once-daily formulation of nifedipine achieved effective control of office blood pressure, similar control was not observed in awake and 24-hour periods in all patients.

Adult↗
PubMed1990

Immune activation is associated with phenylhydrazine-induced anemia in the rat.

Long-term phenylhydrazine (PHZ) treatment caused pronounced anemia and a concomitant increase in the numbers of circulating leukocytes in Long-Evans rats. The leukocytosis was caused mainly by an elevation in mononuclear cells, most notably in the lymphocyte population. PHZ has been reported to cause the direct lysis of erythrocytes by nonimmune mechanisms. However, recent reports indicate that PHZ can cross-link red cell band 3 protein (senescent antigen), resulting in the binding of autologous immunoglobulin G (IgG). Recognition of this complex by macrophage Fc receptor mechanisms triggers rapid erythrophagocytosis-in the spleen and possibly the liver as well. In our study, analysis of the blood, bone marrow, and spleen cells of long-term (1 to 6 weeks) PHZ-treated rats was performed by using flow cytometry. Total serum IgG levels were determined by radial immunodiffusion, and antibodies reactive with red cells that were sensitized to PHZ either in vivo or in vitro were titered by using the indirect Coombs' method. Serum prostaglandin E2 titers also were determined at different time intervals after PHZ administration. The results indicate that PHZ induces an increase in circulating antibody and prostaglandin E2 titers that correlates with the onset of anemia and that the serum of PHZ-treated rats can induce anemia in normal recipients after passive transfer. Cytofluorographic studies revealed a marked increase in the B-cell population of the peripheral blood and spleen and an altered ratio T-helper to T-suppressor cells at certain time intervals after PHZ injection. The results indicate that in addition to inducing senescence-like alterations in erythrocyte membrane proteins, PHZ stimulates the production of the autologous IgG that recognizes these sites and promotes lymphoid blastogenesis, most notably in the B-cell lineage.

Anemia↗
PubMed1988

Correlation between verapamil plasma concentration and P-R prolongation in essential hypertension.

Plasma verapamil concentration was correlated with serial electrocardiographic P-R intervals in patients with essential hypertension receiving immediate-release (80 to 120 mg three times a day) or sustained-release (240 mg daily) verapamil. The mean P-R interval in 22 patients taking placebo and immediate-release verapamil was 0.18 second. The borderline first-degree atrioventricular block of three patients did not change during treatment. Plasma verapamil concentrations of patients with a P-R interval longer than 0.20 second and of those with a P-R interval of 0.20 second or less were 169 +/- 73 ng/mL and 63 +/- 8 ng/mL, respectively. Six patients taking sustained-release verapamil had a maximal mean P-R interval of 0.19 +/- 0.01 second during 24-hour ambulatory electrocardiographic monitoring. P-R intervals were 0.22 second or more in two patients, but they returned to normal by hour 7 for one and by hour 20 for the other patient. In summary, transient P-R prolongation occurred with oral verapamil therapy, but no patient, regardless of baseline P-R interval, developed high-grade atrioventricular block.

Delayed-Action Preparations↗
PubMed1988

Blood pressure load--a better determinant of hypertension.

Noninvasive ambulatory blood pressure monitoring was used to evaluate the diagnosis of hypertension in 168 untreated patients with essential hypertension. On the basis of overall office blood pressure--the mean of 12 measurements, 2 in each of three positions (supine, sitting, and standing) on 2 consecutive days--133 patients were diagnosed as having hypertension (diastolic blood pressure of 90 mm Hg or higher) and 35 as having borderline hypertension (diastolic blood pressure of less than 90 mm Hg). The mean blood pressures for those with hypertension and borderline hypertension were 149/99 and 135/87 mm Hg, respectively. The mean ambulatory diastolic blood pressure was 90 mm Hg or higher in 123 patients during awake hours and in 91 patients during 24 hours. The diastolic blood pressure loads (percentage of ambulatory diastolic blood pressures more than 90 mm Hg) in patients with hypertension and borderline hypertension, respectively, were 69% and 43% during awake hours and 59% and 35% during 24 hours. The systolic blood pressure loads (percentage of systolic readings more than 140 mm Hg) during awake and 24 hours were 56% and 48%, respectively, in patients with established hypertension and 31% and 26%, respectively, in those with borderline hypertension. Thus, ambulatory blood pressure monitoring and blood pressure load provide useful information for diagnosing hypertension.

Adult↗
PubMed1988

Antihypertensive efficacy of lisinopril. Ambulatory blood pressure monitoring.

Noninvasive automatic ambulatory blood pressure monitoring during 24 hours in eight patients with moderate hypertension was used to determine the blood pressure response to lisinopril, an angiotensin-converting enzyme inhibitor. Office, 24-hour ambulatory, awake ambulatory, and sleep ambulatory diastolic blood pressures were decreased from 108 +/- 3, 98 +/- 8, 101 +/- 7, and 87 +/- 14 mm Hg, respectively, at baseline to 83 +/- 4 (P less than or equal to 0.0001), 82 +/- 7 (P less than 0.0001), 84 +/- 7 (P less than 0.0001), and 73 +/- 9 mm Hg (P less than 0.005), respectively, after 20 weeks of lisinopril treatment (dose range, 40 to 80 mg once daily). The diastolic blood pressure loads (percentages of ambulatory diastolic blood pressures more than 90 mm Hg) during 24 hours and during awake hours were 74% +/- 19% and 83% +/- 15%, respectively, at baseline and 24% +/- 19% (P less than 0.0001) and 29% +/- 21% (P less than 0.0001), respectively, during treatment. Heart rate was not altered by lisinopril. In conclusion, lisinopril is an effective antihypertensive agent for the treatment of moderate hypertension, and ambulatory blood pressures and diastolic blood pressure loads are useful for evaluating therapy for hypertension.

Adult↗
PubMed1986

The biology of natural transformation.

Natural transformation is widely distributed among bacteria. Its variations, in terms of specific mechanisms, may in part reflect responses to different selective pressures in different bacteria. We have suggested that both gene transfer and acquisition of carbon, nitrogen, and energy represent physiological needs that may have contributed to the evolution of natural transformation. While natural transformation was the first mechanism of genetic exchange to be detected, it is perhaps the least understood. Our understanding of the mechanism for uptake and incorporation of soluble DNA has increased significantly in the last two decades, but the overall picture of transformation as a biologically significant function is still unfolding. The mechanism by which DNA is released for transformation, the control of genes involved in DNA release and uptake, the potential for transformation in the natural environment, and the potential of natural transformation as a tool for other microbiological studies are but a few of the important issues that remain.

Bacteria↗
PubMed1985

Inability of Pseudomonas stutzeri denitrification mutants with the phenotype of Pseudomonas aeruginosa to grow in nitrous oxide.

Pseudomonas aeruginosa PAO1 reduced nitrous oxide to dinitrogen but did not grow anaerobically in nitrous oxide. Two transposon insertion Nos- mutants of Pseudomonas stutzeri exhibited the P. aeruginosa phenotype. Growth yield studies demonstrated that nitrous oxide produced in vivo was productively respired, but nitrous oxide supplied exogenously was not. The defect may be in electron transport or in nitrous oxide uptake.

Kinetics↗
PubMed1985

Thymidine salvage in Pseudomonas stutzeri and Pseudomonas aeruginosa provided by heterologous expression of Escherichia coli thymidine kinase gene.

Unlike enteric bacteria, Pseudomonas spp. generally lack thymidine phosphorylase and thymidine kinase activities, thus preventing their utilization of exogenous thymine or thymidine and precluding specific radioactive labeling of their DNA in vivo. To overcome this limitation, a DNA fragment encoding thymidine kinase (EC 2.7.1.21) from Escherichia coli was cloned into pKT230, a small, broad-host-range plasmid derived from plasmid RSF1010. From transformed E. coli colonies, the recombinant plasmid bearing the thymidine kinase gene was conjugally transferred to Pseudomonas stutzeri, Pseudomonas aeruginosa, Pseudomonas mendocina, Pseudomonas alcaligenes, and Pseudomonas pseudoalcaligenes. Thymidine kinase activity was expressed in all of these species, and all gained the ability to incorporate exogenous [2-14C]thymidine into their DNA. Thymidine incorporation into P. stutzeri was enhanced 12-fold more in mutants lacking thymidylate synthetase activity. These mutants produced higher levels of thymidine kinase and were thymidine auxotrophs; thymineless death resulted from removal of thymidine from a growing culture.

DNA Replication↗
PubMed1983

Comparison of denitrification by Pseudomonas stutzeri, Pseudomonas aeruginosa, and Paracoccus denitrificans.

A comparison was made of denitrification by Pseudomonas stutzeri, Pseudomonas aeruginosa, and Paracoccus denitrificans. Although all three organisms reduced nitrate to dinitrogen gas, they did so at different rates and accumulated different kinds and amounts of intermediates. Their rates of anaerobic growth on nitrate varied about 1.5-fold; concomitant gas production varied more than 8-fold. Cell yields from nitrate varied threefold. Rates of gas production by resting cells incubated with nitrate, nitrite, or nitrous oxide varied 2-, 6-, and 15-fold, respectively, among the three species. The composition of the gas produced also varied markedly: Pseudomonas stutzeri produced only dinitrogen; Pseudomonas aeruginosa and Paracoccus denitrificans produced nitrous oxide as well; and under certain conditions Pseudomonas aeruginosa produced even more nitrous oxide than dinitrogen. Pseudomonas stutzeri and Paracoccus denitrificans rapidly reduced nitrate, nitrite, and nitrous oxide and were able to grow anaerobically when any of these nitrogen oxides were present in the medium. Pseudomonas aeruginosa reduced these oxides slowly and was unable to grow anaerobically at the expense of nitrous oxide. Furthermore, nitric and nitrous oxide reduction by Pseudomonas aeruginosa were exceptionally sensitive to inhibition by nitrite. Thus, although it has been well studied physiologically and genetically, Pseudomonas aeruginosa may not be the best species for studying the later steps of the denitrification pathway.

Kinetics↗
PubMed1983

Pseudomonas stutzeri and related species undergo natural transformation.

Cells of Pseudomonas stutzeri are naturally transformed by homologous chromosomal DNA; they do not require chemical treatment to become competent. This capacity to undergo natural transformation was found to be shared by the closely related species P. mendocina, P. alcaligenes, and P. pseudoalcaligenes, but was not detectable in strains of P. aeruginosa, P. perfectomarinus, P. putida, P. fluorescens, or P. syringae. P. stutzeri could be transformed either on plates or in liquid medium. Only double-stranded chromosomal DNA was effective; single-stranded DNA and plasmid DNA were not. DNA fragments larger than 10 kilobase pairs were more effective than smaller fragments. The transformation frequency was proportional to DNA concentration from 1 ng/ml to 1 microgram/ml; higher concentrations were saturating. The maximum frequency, about 10(-4) transformants per recipient cell, was obtained with cells from a culture in the early stationary growth phase. A variety of chromosomal mutations have been transformed, including mutations to auxotrophy and to antibiotic resistance. Other systems for genetic exchange in P. stutzeri have not yet been found; transformation offers a means for the genetic analysis of this metabolically versatile organism.

Chromosomes, Bacterial↗
PubMed1983

Evidence for an active role of donor cells in natural transformation of Pseudomonas stutzeri.

The transfer of chromosomal genes in a cell mat of Pseudomonas stutzeri was ca. 10(3) times more efficient per microgram of DNA if DNA was added as a constituent of intact donor cells rather than as a solution. Such intact cell-mediated transfer appears to depend on cell contact. It is independent of the presence of plasmids in donor strains and is DNase I sensitive, thus fitting the usual definition of transformation. It is bidirectional: cells of either strain in a transformation mixture served as the donor and recipients. The donor function in cell contact transformation was inhibited by nalidixic acid but was unaffected by rifampin and streptomycin at growth-inhibiting concentrations. Concentrations of nalidixic acid sufficient to inhibit donor function completely had no effect on the ability of nalidixic acid-resistant recipients to take up DNA from solution. These experiments suggest that certain cells donate DNA to others in the cell mat: they argue against the hypothesis that the function of donor cells is merely cell lysis.

Bacterial Proteins↗
PubMed1982

Involvement of arginine residues in the allosteric activation of Escherichia coli ADP-glucose synthetase.

Inactivation of Escherichia coli ADP-glucose synthetase (EC 2.7.2.27) by the arginine-specific reagents cyclohexanedione and phenylglyoxal resulted primarily from interference with normal allosteric activation. Partial modification by phenylglyoxal resulted in a lessened ability of fructose 1,6-bisphosphate (fructose-P2) to stimulate and of 5'-AMP (5'-adenylate) to inhibit enzymic activity. The apparent affinity for fructose-P2 and the Vmax at saturating fructose-P2 concentrations were decreased by the arginine modification. Fructose-P2, 5'-adenylate, and several other allosteric effectors were able to partially protect the enzyme from inactivation. However, catalytic activity was not decreased by arginine modification under conditions where the enzyme was assayed in the absence of fructose-P2. The two arginine-modifying reagents differed markedly in their reactivity with the enzyme. Cyclohexanedione inactivated the enzyme quite slowly and eventually reacted with at least 14 of the 32 arginines present per subunit. Phenylglyoxal was some 50-fold more effective in inactivation, but it modified only one arginine residue per subunit.

Adenosine Monophosphate↗
PubMed1982

The physiological genetics of denitrifying bacteria.

The genetics of denitrification is a relatively unexplored area that has great promise. Species of Pseudomonas are probably best suited for study because they are widely found among natural denitrifying populations and are quite readily amenable to genetic analysis. The techniques for mutagenesis and for the exchange of chromosomal genes to characterize mutant strains have been well-developed in P. aeruginosa and are being developed in P. stutzeri. Mutants defective in the denitrification of nitrate, nitrite, and nitrous oxide are now available and will aid in describing the catalytic and regulatory elements of the denitrification pathway.

DNA Transposable Elements↗