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Biomedical subjects

D Christensen

Publications and source records attributed to D Christensen.

50 records · Page 3Linked to original sources
PubMed1983

Effects of digoxin in infants with a congested circulatory state due to a ventricular septal defect.

Digoxin alone was used to treat a congested circulatory state in 21 infants (mean age, 2.7 months; mean weight, 3.8 kg) with a ventricular septal defect. The dose was adjusted on the basis of pharmacokinetics to achieve a mean steady-state concentration of 1.6 +/- 0.3 ng of digoxin per milliliter of serum. The mean red-cell level of sodium-potassium ATPase fell from 23.1 +/- 7.0 to 12.6 +/- 5.2 nmol per milligram per minute with treatment. Only 6 of the 21 patients had an inotropic response, as reflected by echocardiographic measurements, but the drug was of clinical benefit to 12 infants (including these 6). These results show that not all infants with a congested circulatory state due to a ventricular septal defect benefit from digoxin therapy. Furthermore, in some subjects clinical improvement occurs in the absence of a measurable inotropic response.

Digoxin↗
PubMed1983

Prediction of recurrence in meningiomas after surgical treatment. A quantitative approach.

The prognostic significance of nuclear count, nuclear area fraction, and mean nuclear area estimated by automatic image analysis was evaluated in benign meningiomas. One hundred thirty-two meningiomas without recurrences, 39 meningiomas that recurred, and 40 first recurrences were examined. The tumors were classified according to age and sex of patients, localization, and histology; and the correlation between these parameters and the recurrence rate was assessed. The nuclear counts were identical in paraffin sections from meningiomas without recurrences (6.1 nuclei per 1,000 micrometer 2) and in meningiomas that recurred (6.4 nuclei per 1,000 micrometer 2). The cell count in the recurrences (7.4 nuclei per 1,000 micrometer 2) was higher than in the primary tumors. The same relationship was found for the nuclear area fractions, which were identical in meningiomas without recurrences and in primary meningiomas that recurred. The nuclear area fraction was increased in recurrences. The mean nuclear areas were identical in all groups. The histological type was of little significance in prediction of recurrence rate, although bone invasion and necrosis were of some significance. We found a higher recurrence rate in parasagittal meningiomas. Meningiomas that recurred appeared in a younger age group than other meningiomas, and the recurrence rate was higher for males than for females.

Adolescent↗
PubMed1983

Effects of acute preload and afterload stress on myocardial function in newborn and adult sheep.

Unanesthetized, chronically instrumented newborn and adult sheep were subjected to acute circulatory preload stress (rapid administration of 30 ml X kg-1 isotonic saline) and afterload stress (intravenous administration of 0.2 mg X kg-1 methoxamine). Variables of circulatory status and myocardial function were monitored continuously during experimental manipulations. Preload stress elevated arterial and venous pressures, reduced the preejection period (PEP) to left ventricular ejection time (LVET) ratio (PEP/LVET), and increased the rate of left ventricular pressure rise (dp/dt) to a comparable extent in newborn and adult subjects. Afterload stress increased arterial and venous pressures to a comparable extent in newborns and adults; the percent changes in PEP (25), LVET (16), PEP/LVET (12) and dp/dt (-21) in newborns were more pronounced than those in adults.

Animals↗
PubMed1982

Immune complex glomerulonephritis and dermal vasculitis following intestinal bypass for morbid obesity.

A kidney and skin biopsy were performed on a patient who developed cryoglobulinemia, polyarthritis, a purpuric skin rash, and acute renal failure four years following jejunoileal bypass for morbid obesity. Morphologic studies revealed a diffuse glomerulonephritis characterized by the presence of numerous subendothelial deposits containing IgG, IgA, C3, Clq, C4, and properdin, and an acute dermal vasculitis associated with similar immune complex deposits. Identical immunoglobulin and complement components were present in the cryoglobulin. In addition, both the cryoglobulin and a renal biopsy eluate containing anti-IgG antibody and antibody against Klebsiella pneumoniae which were present in the patient's stool in large numbers. Combined therapy with steroids and chloramphenicol resulted in marked improvement in the patient's arthritis, skin rash, and renal function. The findings indicate that glomerulonephritis and dermal vasculitis due to the deposition of bacterial antigen-antibacterial antibody complexes may occur as part of a systemic immune complex disease complicating small intestinal bypass.

Adult↗
PubMed1981

Volatile Fatty acids and hydrogen as substrates for sulfate-reducing bacteria in anaerobic marine sediment.

The addition of 20 mM MoO(4) (molybdate) to a reduced marine sediment completely inhibited the SO(4) reduction activity by about 50 nmol g h (wet sediment). Acetate accumulated at a constant rate of about 25 nmol g h immediately after MoO(4) addition and gave a measure of the preceding utilization rate of acetate by the SO(4)-reducing bacteria. Similarly, propionate and butyrate (including isobutyrate) accumulated at constant rates of 3 to 7 and 2 to 4 nmol g h, respectively. The rate of H(2) accumulation was variable, and a range of 0 to 16 nmol g h was recorded. An immediate increase of the methanogenic activity by 2 to 3 nmol g h was apparently due to a release of the competition for H(2) by the absence of SO(4) reduction. If propionate and butyrate were completely oxidized by the SO(4)-reducing bacteria, the stoichiometry of the reactions would indicate that H(2), acetate, propionate, and butyrate account for 5 to 10, 40 to 50, 10 to 20, and 10 to 20%, respectively, of the electron donors for the SO(4)-reducing bacteria. If the oxidations were incomplete, however, the contributions by propionate and butyrate would only be 5 to 10% each, and the acetate could account for as much as two-thirds of the SO(4) reduction. The presence of MoO(4) seemed not to affect the fermentative and methanogenic activities; an MoO(4) inhibition technique seems promising in the search for the natural substrates of SO(4) reduction in sediments.

Journal Article↗
PubMed1977

Sudden death in the late hospital phase of acute myocardial infarction.

Forty-seven patients died suddenly during the late hospital phase of acute myocardial infarction. Risk factors associated with late in-hospital sudden death included prior cardiovascular disease, circulatory failure while in the coronary care unit, and certain arrhythmias and conduction disturbances while in the coronary care unit. These were associated with a twofold to sixfold increase in late in-hospital phase sudden death. The most prevalent risk factor occured in 62% of the sudden-death patients; the highest incidence of sudden death with a single risk factor was 2.6%, and the greatest relative risk was 6.0. Relative risks were uniformly greater for males than females. Multiple factors were associated with a greater risk than single factors. These risk factors characterize the group of sudden-death patients as a whole but do not allow precise identification of individual patients at high risk.

Acute Disease↗
PubMed1975

The effect of vitamin E on haemolysis in paroxysmal nocturnal haemoglobinuria: in vitro and in vivo studies.

The administration of vitamin E, a natural antioxidant, to a patient with paroxysmal nocturnal haemoglobinuria (PNH) failed to diminish the urinary excretion of 59-Fe as monitored by 59-Fe whole body counting and urinary loss of isotope. However, in vitro vitamin E corrected the increased sensitivity of PNH red cells to haemolysis by hydrogen peroxide. These results support the concept that the susceptibility of PNH red cells to lipid peroxidation is an in vitro phenomenon bearing little relation to the mechanism of in vivo haemolysis.

Blood Transfusion↗