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Biomedical subjects

N Lund

Publications and source records attributed to N Lund.

At least 55 records · Page 3Linked to original sources
PubMed1986

Muscle tissue oxygen pressure in primary fibromyalgia.

Trigger points in painful muscle are a characteristic sign in patients with primary fibromyalgia. The MDO oxygen electrode was used to evaluate oxygenation in the subcutaneous tissue and in trigger points in the trapezius and brachioradial muscles. Ten patients and 8 normal controls were studied. The results in the patients were abnormal, with scattered or slalom-slope histograms, indicating low tissue oxygenation. The controls were normal, except in one case. The conclusion is that in patients with primary fibromyalgia, the muscle oxygenation is abnormal or low, at least in the trigger point area of the muscles.

Adult↗
PubMed1985

Effects of anesthetics on regional hemodynamics in normovolemic and hemorrhaged rats.

Twenty-nine male Sprague-Dawley rats were divided into four groups based on anesthetic exposure, i.e., awake animals and those receiving anesthesia produced by chloralose-urethan, pentobarbital, or by midcollicular brain stem transsection. Before and after hemorrhage (30% of the estimated blood volume), cardiac output (CO) and regional blood flows were measured by the microsphere method. Arterial blood gases and lactate (L) and pyruvate (P) were also determined. CO and regional blood flows were greatest and the L/P ratio was least in awake animals both before and after hemorrhage. In normovolemic rats, the frequency of altered values (as compared with those in awake animals) was similar for all anesthetic techniques, whereas the CO and regional blood flow responses to hemorrhage were altered less frequently in decerebrated animals. Decerebration may be the preferable procedure if the intent is to produce responses in anesthetized animals similar to those in awake rats. If the intent is to study hemodynamics in a specific organ, the selection of an anesthetic technique should be guided by the individual anesthetic effects on that particular tissue.

Anesthesia, General↗
PubMed1985

Infanticide, physicians, and the law: the "Baby Doe" amendments to the Child Abuse Prevention and Treatment Act.

Infanticide, like most other species of homicide, is probably coeval with the human race itself. In modern Western civilization, what were formerly the most powerful incentives to infanticide have virtually disappeared. As with other social problems that affluence has seemed to solve, however, infanticide has reappeared in a new form that seems to have been made possible by affluence itself. This "new infanticide" occurs in a place whose very existence is the result of a tremendously wealthy society's devotion to its most vulnerable and least "useful" members. The modern neonatal intensive care unit, which treats, and often saves, extremely ill newborn children, who during most of history would surely have died, has proven to be a setting where many of the age-old incentives for infanticide have begun to operate again. The "new infanticide" consists of withholding food or needed medical treatment from selected infants who suffer from one or more serious, though treatable, medical problems. The national government has now enacted legislation designed to curtail the practice of infanticide by the medical profession. This paper traces the genesis of that legislation, explores the problem to which it is addressed, and evaluates its prospects for success.

Abnormalities, Multiple↗
PubMed1985

Local skeletal muscle surface oxygen pressure fields after high-energy trauma.

In the assessment of viability of traumatized muscle tissue clinical signs, including colour, consistency, capillary bleeding and contractility have been commonly used. One of these signs, discolouration, has been shown in earlier studies to be associated with impaired circulation and severe and irreversible changes of muscle electrolytes and energy metabolism. In this study the circulation and tissue oxygen pressure fields were studied on either side of the "demarcation line" between discoloured and normally coloured areas of traumatized muscle tissue. Anaesthetized pigs were injured in one thigh with a high velocity spherical steel missile. The microcirculatory flow of the traumatized muscle was studied by measuring the clearance of 133Xenon from the surface of the muscle and tissue oxygen pressure (PtO2) was measured with an MDO electrode. Measurements were done before and 1, 3 and 5 hours after the trauma. A markedly decreased or absent flow as well as very low PtO2 values were found within areas of discolouration. In the adjacent normally coloured areas no such changes were noted and the values of these areas resembled those of the contralateral untraumatized leg. The results agree with those of earlier studies of circulation and metabolic changes indicating that discolouration is a useful sign in the clinical assessment of muscle viability after high-energy trauma.

Animals↗
PubMed1985

Regional blood flow in the pig cortex during increased carbon dioxide pressure with local atraumatic application of 133Xenon.

A method for measuring regional cerebral blood flow with local application of 133Xenon was used. A polyester film was placed on pig cerebral cortex under which 0.6-1.3 mCi of 133Xenon dissolved in 2-4 microliter of saline was applied atraumatically. The wash-out process was registered with an external detector. The wash-out curves were not contaminated by extra-cerebral tissue and there was no 'looking-through phenomenon' of non-perfused parts of the brain. Regional cerebral blood flow was 142 +/- 14 ml X 100 g-1 X min-1 (mean +/- S.D.) in grey matter and 34 +/- 9 ml X 100 g-1 X min-1 in white matter when PaCO2 was normal (4.92 +/- 0.43 kPa). When PaCO2 was increased to 9.3 +/- 1.39 kPa regional cerebral blood flow was increased to 313 +/- 60 ml X 100 g-1 X min-1 in grey matter and to 46 +/- 20 ml X 100g-1 X min-1 in white matter.

Animals↗
PubMed1985

Acute coronary occlusion: oxygen pressure in the border zone studied in the pig.

The area between ischemic and normal myocardium after acute coronary occlusion-the border zone-is of great interest. It has been proposed that this area contains reversibly damaged myocardium subjectable to myocardial salvage. Twenty Swedish land race pigs were studied, 13 after acute occlusion of the left anterior descending coronary artery (LAD), while seven served as controls. We measured tissue oxygen pressures (ptO2) subepicardially with the MDO electrode. This is a multiwire surface electrode measuring ptO2 with eight individual platinum wires. Hundred and twenty values were collected in each measuring situation. The electrode was positioned on the lateral border zone, measurements were performed before and 5, 30 and 120 min after LAD occlusion. In five cases successful measurements were performed across the border zone. A mixture of normal and ischemic ptO2 values was found 5 min after occlusion. After 30 min of occlusion the number of ischemic values decreased and this was particularly the case after two hours of occlusion. The results support the view that the border zone was very narrow. The reduced number of ischemic values after two hours of permanent LAD occlusion also indicated that the border zone may be narrow but not necessarily fixed but instead dynamic. In this case there was a spontaneous decrease of the ischemic area.

Animals↗
PubMed1984

A multipoint micro antimony pH electrode for tissue surface measurements.

Based on monocrystalline antimony we have developed a multipoint tissue surface pH electrode. The six electrodes were produced by spark cutting from a large antimony single crystal. The electrodes were then cast in epoxy resin in a ring shaped structure which fitted around the MDO oxygen electrode. The antimony electrode was ground and polished to expose an undisturbed closely packed crystal plane of antimony to the measuring solution. Before and after monitoring periods standardization was performed in TRIS buffers of pH 6.72, 7.32 and 7.74 at 37 degrees C. Antimony electrode potential is influenced by oxygen. Therefore, mean tissue oxygen pressure was registered simultaneously with an MDO electrode. The oxygen sensitivity factor used in this study was 18mV/logpO2. The correction factor for the antimony electrode oxygen dependence, measured in vitro, seemed to be correct also for the in vivo state. This, however, needs further investigation. To illustrate the usefulness of the multipoint pH electrode seven normal state rabbits were studied, and thereafter four - one each in a hypoxic, hypocarbic, hypovolemic or hyperoxic situation. In the normal state tissue pH measured on a skeletal muscle surface varied from 7.0 to 7.4. In the case of tissue microcirculation shutdown (in the hypocarbic or the hypovolemic situations), the initial reaction was a scattering of the pH values, and then the development of tissue acidosis. Our conclusion is that the use of a multipoint pH sensor enables improved and more detailed monitoring of the tissue acid-base status.

Animals↗
PubMed1983

Effect of increased blood oxygen affinity on skeletal muscle surface oxygen pressure fields.

A chronic left displacement of the blood O2 dissociation curve (ODC) was achieved in rats by administering cyanate over a period of 14 days. Control rats received NaCl. An acute left displacement of the ODC was achieved by exchange transfusion with bisulfite-treated erythrocytes. Control rats for this series received an exchange transfusion with fresh heparinized blood. In both series, skeletal muscle surface O2 pressure fields (expressed as PO2 histograms) were measured with the rats anesthetized, curarized, and artificially ventilated. The animals with chronically left-shifted ODC had normal PO2 histograms (for definition see DISCUSSION) when breathing air; during hypoxia (FIO2 0.12) four of the eight experimental and three of the seven control animals developed abnormal histograms, and all animals had normal histograms on return to air breathing. The majority, but not all, of the animals that were to receive exchange transfusions of left-shifted ODC blood had normal histograms before the transfusion, which caused some to become abnormal and others to become normal. Similar results were obtained in the control animals that received normal blood. The results do not provide evidence for an adverse effect of a left-shifted ODC on muscle tissue oxygenation.

Animals↗
PubMed1983

Tissue oxygenation and muscular substrate turnover in two subjects with high hemoglobin oxygen affinity.

Oxygen transport to and substrate turnover in leg muscle were studied at rest and during light and heavy upright bicycle exercise in two brothers with a hereditary hemoglobinopathy associated with high oxygen affinity (P50 = 13 mmHg). Femoral venous oxygen tension was below normal and femoral venous oxygen saturation above normal at rest and during exercise. Thus, the arterial-femoral venous oxygen saturation difference was decreased. Despite a compensatory increase in hemoglobin concentration, the arterial-femoral venous oxygen content difference tended to be below normal at heavy exercise. Approximately 25% of the oxygen was delivered via the abnormal hemoglobin at relative heavy exercise. Arterial lactate levels, lactate release, and muscle lactate concentration were not increased at any level of exercise. Glucose, alanine, pyruvate, and glycerol turnover were essentially normal, but the glycogen and creatine phosphate stores were abnormally depleted at the termination of heavy exercise. The exercise electrocardiogram (ECG) was normal, indicating that myocardial oxygenation was adequate. Muscle-surface oxygen pressure fields were normal at rest (not investigated during exercise). It is concluded that the high oxygen affinity of the hemoglobin in our two subjects did not lead to heart or skeletal muscle hypoxia during heavy exercise, as judged from the ECG and from the leg lactate turnover. Despite the lack of evidence for muscle hypoxia, the subjects experienced leg muscle fatigue and the creatine phosphate and glycogen stores were depleted more than normally.

Adenosine Triphosphate↗
PubMed1982

Effects of reinforcement, proximity, and orientation on verbal behavior of female schizophrenics.

Evaluated effects of reinforcement, proximity, and orientation on verbal behavior of female schizophrenics. Sixty-four inpatient state hospital volunteers (36 schizophrenics and 33 hospitalized controls) either were reinforced verbally or nonreinforced for construction of appropriate sentences. Also, participants were exposed to near or far proximity as well as direct or indirect orientation. Results indicated that schizophrenics performed best in the indirect orientation condition. While no differential group effects were seen across diagnosis, participants on the average responded more effectively when reinforced. These findings are contradictory to those reported in earlier studies of verbal conditioning in schizophrenics. Discussed were the detrimental effects of attentional demands on verbal conditioning in schizophrenics and the effectiveness of verbal reinforcement across hospitalized patients.

Adult↗
PubMed1982

Detection of brain-damage in schizophrenics as measured by the Whitaker Index of Schizophrenic Thinking and the Luria-Nebraska Neuropsychological Battery.

Neuropsychological performance of schizophrenics with and without brain-damage was measured by the Whitaker Index of Schizophrenic Thinking and the Luria-Nebraska Neuropsychological Battery. Inpatient volunteers (11 brain-damaged and 15 non-brain-damaged) with a diagnosis of schizophrenia were administered both tests individually. Results indicated that 8 of the 14 summary scales of the Luria-Nebraska but none of the 5 scores on the Whitaker differentiated between groups. While cognitive variables as measured by the Whitaker may be further impaired with organicity, other variables measured by the Luria-Nebraska were more effective in differentiating between groups.

Adult↗
PubMed1982

[The effect of low-molecular hydroxyethyl starch and dextran 60 on the muscle oxygen supply in intensive care patients].

Skeletal muscle pO2 measurements were performed in two groups of critically ill patients (total n = 19) using the multiwire surface electrode (MDO) by Kessler and Lübbers to evaluate oxygen supply of the measured time. Muscle pO2 in the first group (n = 9) was recorded before and after i.v. application of 250 ml low molecular 6% hydroxyäthylstarch, Mw 40,000, in the second group (n = 10) before and after 250 ml 6% dextran 60. Both groups were tested under normoxemia and hyperoxemia respectively. It was the aim of the study, to examine if these colloidale substances may improve oxygen supply in skeletal muscle. Even the small amount of 250 ml l. m. HAS or dextran 60 respectively was able to raise the mean muscle pO2 of the measured patients significantly. The effect was similar in both groups. Since oxygen transport capacity remained uneffected, the improved oxygen supply after administration of l. m. HAS and dextran 60 must be considered as a beneficial effect of these drugs on the blood flow properties in the capillary bed.

Adolescent↗