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Biomedical subjects

D Campbell

Publications and source records attributed to D Campbell.

At least 343 records · Page 19Linked to original sources
PubMed1982

Electrical and contractile activities of the human rectosigmoid.

Electrical and mechanical activities were recorded from the rectosigmoid of normal subjects using an intraluminal recording tube with two sets of bipolar electrodes and strain gauges. Four distinct types of electrical activities were recorded. (1) Electrical control activity (ECA). This activity varied in amplitude and frequency over time and the control waves were not phase-locked. The means of dominant frequency components in the lower and higher frequency ranges were 3.86 +/- 0.18 SD and 10.41 +/- 0.46 SD c/min, respectively. The overall dominant frequency component was mostly in the lower frequency range of 2.0-9.0 c/min. (2) Discrete electrical response activity (DERA). This activity appeared as short duration bursts (less than 10 s) of response potentials whose repetition rate was in the total colonic electrical control activity frequency range of 2.0-13.0 c/min. The mean duration of this activity was 2.24 +/- 1.30 SD s. (3) Continuous electrical response activity (CERA). This activity appeared as long duration bursts (greater than 10 s) of response potentials which were not related to electrical control activity. Its mean duration was 14.78 +/- 3.68 SD s. This activity generally did not propagate. (4) Contractile electrical complex (CEC). This activity appeared as oscillations in the frequency range of 25-40 c/min and was also not related to electrical control activity. This activity propagated, sometimes proximally and sometimes distally. Its mean duration was 18.87 +/- 9.22 SD s. The latter three types of electrical activities were all associated with different types of contractions. These contractions, however, did not always occlude the lumen. Colonic electrical control activity controls the appearance of discrete electrical response activity in time and space. The mechanism of generation of continuous electrical response activity and contractile electrical complex is not yet known.

Adolescent↗
PubMed1982

Quantification of the inflammatory reaction and collagen accumulation in an experimental model of open wounds in the rat. A methodological study.

An experimental model for studying the early healing of open wounds in the rat is described. With this model, exudate is easily collected, a standardized granulation tissue is achieved at different post-wounding time intervals and local treatment of the wounds is possible. The model involves the use of stainless steel rings with covers, fastened to the edges of two circular full-thickness open wounds, one on each side of the animal's back in the thoracic region. Blood flow and water content of the granulation tissue were determined acutely 3, 5, 7 and 10 days after wounding. The collagen accumulation in the granulation tissue was assessed by the amount of hydroxyproline, at the same time intervals. The amount of exudate which accumulated in the chamber was measured daily. Blood flow in the granulation tissue, as measured by radioactive microspheres, reached a maximum of 947 ml X min-1 X (100 g dry weight)-1 7 days after wounding. The water content, as assessed by freeze-drying, also reached its peak on the 7th day (5.5 ml X (g dry weight)-1). Changes in water content were found to be due to changes in interstitial fluid volume, as studied by 59Fe-labelled erythrocytes and 51Cr-EDTA. The amount of hydroxyproline in the granulation tissue increased from 22 micrograms X (mg dry weight)-1 on day 3 to 37 micrograms X (mg dry weight)-1 on day 10. Exudation increased to 28 microliters X h-1 X cm2-1 on day 4 and then declined. The results suggest that the inflammatory reaction, expressed as alterations in blood flow and water content, reaches a maximum on day 7 after wounding. The data also demonstrate a continuous increase in the collagen content of the granulation tissue during the 10-day period of observation. In addition, exudation was found to reach a peak on the 4th to 5th day, and then declined.

Animals↗
PubMed1982

Energy cost of growth of premature infants.

The objective of this paper is to review approaches to the determination of the energy cost of growth in premature infants. Two approaches are compared: one based on the composition of weight gain, and one based on the determination of energy balance. Data are lacking on the composition of weight gained by the premature infant after birth, while the composition of fetal weight gain and its energy cost can be calculated from data on fetal body composition. These calculations show that energy storage amounts to less than 8.4 kJ/g weight gain below a body weight of 2 kg; the total energy cost of growth is less than 10.5 kJ/g. Estimates twice as high have been obtained from energy balance studies of growing premature infants and older infants. We conclude that the energy cost of growth in premature infants is still uncertain and requires further study.

Body Composition↗
PubMed1981

Blood carboxyhaemoglobin and cyanide levels in fire survivors.

Blood carboxyhaemoglobin and cyanide concentrations were measured in 53 fire survivors, 36 of whom had clinical evidence of smoke inhalation. Carboxyhaemoglobin and cyanide levels were raised only in patients with smoke inhalation. Blood carboxyhaemoglobin measurement can be used to confirm the diagnosis of severe smoke inhalation in cases in which the clinical data are inconclusive, provided that the time of sampling after exposure is taken into account. A nomogram has been constructed for this purpose. There is no quick method of measuring blood cyanide levels, but the close relation between cyanide and carboxyhaemoglobin levels suggests that carboxyhaemoglobin concentrations, which can be rapidly and easily measured, could be used to identify those who might benefit from treatment with cyanide antidotes.

Apnea↗
PubMed1981

Decerebrate rigidity produced in cats by focal stereotactic radiofrequency lesions.

A method of producing decerebrate rigidity in cats by means of a radio frequency current was developed. Adequate control of the extent an shape of the lesions necessitated a preliminary investigation of the relationship between the intensity and duration of current, the size of the lesion, and the tissue impedance before and after destruction; this was performed on guinea pigs. The mesencephalic reticulum in cats was identified by depth microelectrode recording and electrical stimulation. Unilateral, midline, and combined stereotactic radiofrequency lesions were made. The anatomical location, the pathological characteristics, and the physiological significance of the lesions with regard to the production of decerebrate rigidity and of the other clinical reactions of the animals are discussed.

Animals↗
PubMed1981

Which external fixation device?

Seven external fixation frames which are used for the treatment of fractures have been evaluated. The features of these devices are presented and some of the advantages and disadvantages of each are described.

Bone Nails↗
PubMed1981

The comparative stiffness of external fixation frames.

The stiffness of 6 external fixation frames was compared by measuring the deflection which occurred at an unstable fracture, created in a tibia in vitro. All tests were repeated with the frames applied to pins brazed into a steel tube, in order to eliminate any errors caused by variation in the quality of the bone under test. The results of these tests are presented and observations are made on some design features of the frames. It was found that the 2 most critical factors which determined the stiffness of a frame were the diameter and the number of pins used to transfix the bone. Other factors, such as the stiffness of the connecting bar, were of secondary importance.

Biomedical Engineering↗
PubMed1981

Liver blood flow and oxygen consumption during metabolic acidosis and alkalosis in the greyhound.

1. Hepatic arterial and portal venous blood flow and hepatic oxygen consumption were measured in two groups of greyhounds anaesthetized with pentobarbitone. Flows were measured with electromagnetic flowmeters. 2. In the first group the effects of metabolic acidosis produced by the infusion of a molar solution of lactic acid were studied. In the second group the effects of metabolic alkalosis produced by the infusion of a molar solution of sodium bicarbonate were studied. 3. In the acidotic group hepatic arterial blood flow decreased from 35.2 to 9.6 ml min-1 100 g-1 of liver whereas portal venous blood flow increased from 94.2 to 126.1 ml min-1 100g-1 of liver. Total liver blood flow was unchanged. Hepatic oxygen consumption increased, but not significantly, while hepatic venous oxygen content decreased significantly. Hepatic arterial resistance increased from 1.18 to 2.77 mmHg min-1 ml-1 while peripheral resistance was virtually unchanged. Portal venous pressure increased from 7.08 to 11.6 mmHg. 4. In the alkalotic group portal venous blood flow increased from 112 to 137 ml min-1 100 g-1 of liver. Hepatic arterial blood flow increased, but not significantly. Total liver blood flow increased from 151 to 185 ml min-1 100 mg-1 of liver. There were no significant changes in hepatic oxygen consumption. 5. It is concluded that metabolic acidosis reduces the supply of oxygen to the liver owing to the reduction in hepatic arterial blood flow and is therefore potentially harmful, whereas metabolic alkalosis probably has no biologically significant effect on liver blood flow.

Acidosis↗
PubMed1981

Differential mitotic stability of yeast disomes derived from triploid meiosis.

The frequencies of recovered disomy among the meiotic segregants of yeast (Saccharomyces cerevisiae) triploids were assessed under conditions in which all 17 yeast chromosomes were monitored simultaneously. The studies employed inbred triploids, in which all homologous centromeres were identical by descent, and single haploid testers carrying genetic markers for all 17 linkage groups. The principal results include: (1) Ascospores from triploid meiosis germinate at frequencies comparable to those from normal diploids, but most fail to produce visible colonies due to the growth-retarding effects of high multiple disomy. (2) The probability of disome formation during triploid meiosis is the same for all chromosomes; disomy for any given chromosome does not exclude simultaneous disomy for any other chromosome. (3) The 17 yeast chromosomes fall into three frequency classes in terms of disome recovery. The results support the idea that multiply disomic meiotic segregants of the triploid experience repeated, nonrandom, post-germination mitotic chromosome losses (N + 1 leads to N) and that the observed variations in individual disome recovery are wholly attributable to inherent differences in disome mitotic stability.

Aneuploidy↗
PubMed1981

Peritransplant fluid collections. Ultrasound evaluation and clinical significance.

Gray-scale ultrasonography was used to detect, localize, and guide percutaneous aspirations of peritransplant fluid collections. Fifty-one (51%) transplant recipients had abnormal fluid collections; 18 of these patients required surgery. Analysis of the 23 proved fluid collections (10 lymphocytes, 7 abscesses, 4 urinomas, and 2 hematomas) revealed certain sonographic and temporal patterns. Lymphoceles were the most common cause of an obstructed transplant and were usually septated. Most of the undiagnosed fluid collections were small and crescentic and were located in the abdominal wall. They usually did not enlarge or resolve on serial ultrasound examinations. A role for ultrasound in the management of peritransplant fluid collections is proposed.

Abscess↗