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Biomedical subjects

S Holm

Publications and source records attributed to S Holm.

At least 163 records · Page 9Linked to original sources
PubMed1993

The spare embryo--a red herring in the embryo experimentation debate.

Whenever embryo experimentation is discussed, the question of whether it is preferable to use spare or specifically produced ('research') embryos for destructive embryo experimentation always enters the debate at some stage. This question is analysed, and it is suggested that the distinction is morally uninteresting, but rhetorically useful for both sides in the debate. It is further suggested that part of the force of this distinction is caused by the fact that it is parasitic on a real moral distinction based on the degree to which the gametes used in the experiment are obtained by explicit or implicit coercion.

Coercion↗
PubMed1993

Average blood flow and oxygen uptake in the human brain during resting wakefulness: a critical appraisal of the Kety-Schmidt technique.

The Kety-Schmidt technique can be regarded as the reference method for measurement of global average cerebral blood flow (average CBF) and global average cerebral metabolic rate of oxygen (average CMRO2). However, in the practical application of the method, diffusion equilibrium for inert gas tracer between the brain and its venous blood is not reached. As a consequence, normal values for CBF and CMRO2 of 54 ml 100 g-1 min-1 and 3.5 ml 100 g-1 min-1 obtained with the Kety-Schmidt technique are an overestimation of the true values. Using the Kety-Schmidt technique we have performed 57 measurements of CBF and CMRO2 during EEG-verified wakeful rest in young normal adults. In order to estimate the equilibrium values for CBF and CMRO2, a simple computer-based simulation model was employed to quantitate the systematic overestimation caused by incomplete tracer equilibrium. When correcting the measured data, we find that the true average values for CBF and CMRO2 in the healthy young adult are approximately 46 ml 100 g-1 min-1 and approximately 3.0 ml 100 g-1 min-1. Previous studies have suggested that some of the variation in CMRO2 values could be ascribed to differences in cerebral venous anatomy. However in the present study, no correlation between CMRO2 and cerebral venous anatomy as imaged by magnetic resonance angiography could be established. Our data show that the interindividual variation of CMRO2 is 11% (coefficient of variation).

Adult↗
PubMed1993

What is wrong with compliance?

Non-compliance is a label often used about patients who do not follow therapeutic advice. This paper analyses the notion of compliance, and tries to show that this notion is inextricably bound to a paternalistic conception of the doctor-patient relationship. It is proposed that we should perhaps not talk so much about the non-compliant patient, but instead shift the focus towards the non-compliant doctor.

Disclosure↗
PubMed1993

Middle cerebral artery blood velocity and cerebral blood flow and O2 uptake during dynamic exercise.

Results obtained by the 133Xe clearance method with external detectors and by transcranial Doppler sonography (TCD) suggest that dynamic exercise causes an increase of global average cerebral blood flow (CBF). These data are contradicted by earlier data obtained during less-well-defined conditions. To investigate this controversy, we applied the Kety-Schmidt technique to measure the global average levels of CBF and cerebral metabolic rate of oxygen (CMRO2) during rest and dynamic exercise. Simultaneously with the determination of CBF and CMRO2, we used TCD to determine mean maximal flow velocity in the middle cerebral artery (MCA Vmean). For values of CBF and MCA Vmean a correction for an observed small drop in arterial PCO2 was carried out. Baseline values for global CBF and CMRO2 were 50.7 and 3.63 ml.100 g-1.min-1, respectively. The same values were found during dynamic exercise, whereas a 22% (P < 0.0001) increase in MCA Vmean was observed. Hence, the exercise-induced increase in MCA Vmean is not a reflection of a proportional increase in CBF.

Adult↗
PubMed1993

Contralateral somatosensory neglect in unrestrained rats after lesion of the parietal cortex of the left hemisphere.

Three groups of rats were studied: a sham operated control group and two groups in which the parietal "association" cortex had been ablated in the left and right hemispheres respectively. Twenty-four hours and 8 days postoperatively the animals were subjected to a test in which their responsiveness to lateralized somatosensory stimuli was measured while the rats were left unrestrained. Additionally, an activity cage locomotion test followed immediately upon both tests of somatosensory responsiveness. Twenty-four hours postoperatively the animals in which the parietal cortex of the left hemisphere had been ablated demonstrated a significant contralateral neglect of somatosensory stimuli while the group in which the right parietal cortex had been ablated only exhibited a non-significant tendency to a contralateral neglect. While the activity cage test did not reveal an overall difference in the activity level of the three groups the latency to initiate locomotion in the activity cage was found to be significantly decreased in both ablated groups. Eight days postoperatively both ablated groups appeared fully recovered. It is concluded that ablations of the parietal "association" cortex of the rat are associated with a syndrome of contralateral somatosensory neglect that can even be demonstrated if the animals are left unrestrained during testing.

Animals↗
PubMed1992

[Written patient information. Analysis of Danish biomedical research programs].

All patients involved in biomedical research must, according to the Helsinki II declaration, receive complete verbal and written information about the project. Valid consent must be based on adequate information. This study analyses all of the 225 written patient information sheets submitted for approval to the regional research ethical committee covering the three southernmost counties in Jutland (Denmark) during the years 1989 and 1990. Linguistic analysis shows that the information is written in a difficult style with a median readability index of 48.2. It is generally recommended that information directed to the general public should have a readability index below 40 (approximately the level of the popular press). Analysis of information content shows that several important pieces of information are often missing: for instance, information about the name of the leader of the research and about the fact that the relationship with the institution will not be adversely affected by a refusal to participate in the research programme.

Denmark↗
PubMed1992

Bite-force development, metabolic and circulatory response to electrical stimulation in the canine and porcine masseter muscles.

The development of fatigue was investigated by electrical stimulation in 15 domestic pigs (1 yr old, 70-90 kg body weight) and seven adult dogs (3 yr old, 45 kg body weight). After anaesthesia, silver electrodes were implanted in the anterior and posterior parts of the right masseter muscles. The contralateral muscle was used as control. The bite force was measured. Muscle biopsies were obtained from the anterior, central and posterior parts, and were immediately frozen in liquid nitrogen. A fluorometrical analysis by enzymatic methods for glycogen, glucose, creatine phosphate, NAD, NADH, lactate and pyruvate was made. Blood flow was measured by 133Xe wash-out; oxygen consumption was monitored with an oxygen electrode. The porcine masseter was continuously stimulated for 60 min (100 V, 4 Hz and 2 ms). The canine masseter was intermittently stimulated (100 V, 20 Hz and 2 ms). The contraction was repeated four times, with a 10-min rest between. The porcine masseter could sustain longer endurance times than the canine masseter, which was easily fatigued. A marked substrate depletion was evident. The precontractional contents of glycogen, glucose and creatine phosphate were reduced. Lactate accumulation was evident (2-4 times more in the porcine and 4-8 times more in the canine masseter). The NADH concentration increased and the NAD content decreased. Blood-flow impairment (80% reduction in the dog, 60% in the pig) was observed. After the contraction phase, there was a hyperaemia (58% elevation of blood flow in the pig masseter, 45% in the canine). The oxygen tension followed in magnitude and time the blood-flow changes. These circulatory variables returned to normal after recovery. The high degree of substrate depletion, blood-flow impairment and a simultaneous decrease in oxygen transport to the contracted muscle, in combination with a prominent lactate accumulation, may induce a decrease in bite-force production.

Animals↗
PubMed1992

Temporomandibular joint dysfunction. Connective tissue variations in skin biopsy and mitral valve function.

Ten women with temporomandibular joint dysfunction and general joint hypermobility (score, 4 to 8) and 10 symptom-free female volunteers without systemic laxity (score, 0 to 2) were selected for the study. A biopsy of connective tissue from arm skin found that the total collagen concentrations were lower and the proteoglycan values were higher in the hypermobile TMJ patients than in the control subjects. The mitral region of the heart was inspected by echocardiography. Eight patients and four controls had slightly abnormal echocardiographic findings. Two patients fulfilled the criteria for mitral valve prolapse. The patients had significantly more musculoskeletal complaints than did the controls. The study suggests an association between joint hypermobility, abnormal skin connective tissue composition, mitral valve malfunction, and musculoskeletal disorders in young women with TMJ dysfunction, especially internal derangement.

Adult↗
PubMed1992

Gliadin-specific and cow's milk protein-specific IgA in human milk.

The presence of gliadin-specific IgA and IgG antibodies in colostrum and serum of 140 newly delivered mothers was assessed by enzyme-linked immunosorbent assay. In addition, cow's milk protein (CMP)-specific IgA was determined in the colostrum samples. From 14 of the mothers longitudinal milk samples were obtained after 1 and 2 months of lactation and from 12 mothers after 3 months. Gliadin-specific IgA was found in 97.1% and gliadin-specific IgG in 9.3% of the colostrum samples. Gliadin-specific IgA was detected in mature samples but at significantly lower levels after 1, 2, and 3 months of lactation (p less than 0.01) as compared with colostrum. Gliadin-specific IgA was found in 2.8% of the serum samples and gliadin-specific IgG in 40%; however, the levels of both isotypes were low. CMP-specific IgA was found in 78.1% of the colostrum samples. It is concluded that IgA antibodies to two common food proteins are frequently found in human milk and that food-specific IgA present in milk may play a role in adapting the infant's immune reactions to food antigens in the gut.

Animals↗
PubMed1992

Quantitative assessment of aortic regurgitation by combined two-dimensional, continuous-wave and colour flow Doppler measurements.

The width of the regurgitant jet at the aortic valve plane, i.e. the core flow diameter, the ratio of the jet width to the left ventricular outflow diameter, the regurgitant volume and regurgitant fraction were determined using two-dimensional, continuous wave and colour flow Doppler echocardiography. The relationship between the non-invasive measurements and semiquantitative angiographic grading of the regurgitant flow (1 + to 4+) was examined in a primary group of 20 patients with chronic aortic regurgitation. Cut-off points for the non-invasive measurements were selected so as to separate patients with mild or moderate regurgitation (1+ or 2+) from patients with moderately severe or severe regurgitation (3+ or 4+). These cut-off points were prospectively applied in a new group of 35 patients with aortic regurgitation to predict the angiographic grading. Jet width correctly predicted the angiographic grading in 86% of cases, the ratio of the jet width to the outflow diameter in 83% of cases, the regurgitant volume in 86% of cases and the regurgitant fraction in 91% of cases. We conclude that the severity of aortic regurgitation as determined by angiographic grading can be estimated with reasonable accuracy by non-invasive techniques based on colour flow imaging.

Adult↗
PubMed1992

Increased protein absorption after acute gastroenteritis in children.

We investigated the intestinal absorption of the macromolecule human alpha-lactalbumin during and after an episode of acute gastroenteritis in children. Twenty children were studied in the acute phase and 17 excreted rotavirus. Eleven children were studied again 5-8 weeks later (convalescent phase). Human alpha-lactalbumin serum concentrations in the acute phase were similar but in the convalescent phase they were significantly (p less than 0.001) higher than those in the reference children. The serum concentrations were also higher in the convalescent than in the acute phase (p = 0.021). This study suggests that there is an increased absorption of proteins from the gut into the circulation 5-8 weeks after rotavirus gastroenteritis.

Acute Disease↗
PubMed1992

Mental stress and cognitive performance do not increase overall level of cerebral O2 uptake in humans.

We measured cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF), and cerebral lactate output during rest, during the execution of mental arithmetic, and during mental stress induced by physical and psychological annoyance. Measurements were performed in healthy volunteers by use of the Kety-Schmidt technique with 133Xe as the inert gas. Electroencephalographic desynchronization and highly significant increases in plasma catecholamines and heart rate verified that the test measurements were performed during conditions differing distinctly from the resting state. In accordance with an earlier study (Sokoloff et al. J. Clin. Invest. 34: 1101-1108, 1985), a minimal and nonsignificant 1% reduction of global CMRO2 during mental arithmetic was observed, signifying that this form of mental activation was unassociated with any detectable increase in overall cerebral synaptic activity. Mental stress induced a slight but highly significant (P less than 0.002) 6% reduction in global CMRO2. This finding is in contrast to results from earlier investigations and contradicts the generally accepted notion of an association between mental arousal and a diffuse upregulation of cerebral synaptic activity. During mental arithmetic and mental stress, cerebral lactate output increased by 207 and 344%, respectively, but because of large individual variations in the measured responses, the elevations reached statistical significance only during mental arithmetic.

Adult↗
PubMed1992

Septic shock induced by group A streptococcal infection: clinical and therapeutic aspects.

During 1988 and 1989 > 500 cases of serious group A streptococcal infections were reported in Sweden, many with a fatal outcome. We report here on 11 consecutive patients with septic preshock/shock and multiorgan failure, including acute renal failure. 10 had verified group A streptococci (GAS) serotype T1M1 infections while 1 patient was culture negative but with clinical signs of severe infection and serological evidence of GAS infection. Presenting symptoms were high fever, relative bradycardia, edema and renal failure. In all patients the condition deteriorated despite conventional treatment including volume substitution and antibiotics. Systolic blood pressure was transiently < 80 mmHg in 10 patients and 9 of them needed infusion of inotropic agents to avoid fatal circulatory shock. In 9 patients respiratory aid was instituted and 7 were dialysed. Plasma exchange was performed in 7, while the remaining 4 received transfusions with blood and plasma without plasma exchange. 10 patients improved and were discharged within 8 weeks. One woman died within 2 days after admission to the hospital. Renal function recovered in all survivors, with a follow-up serum creatinine < 80 mumol/l. The complicated clinical picture in these patients with many simultaneous therapeutic events confounds the interpretation of the effect of single actions. The favourable outcome in these severely ill patients suggests that potent inotropic agents, immunoglobulin therapy and plasma exchange might be beneficial in severe streptococcal disease when conventional treatment fails.

Adolescent↗
PubMed1991

T lymphocytes inhibit the vascular response to injury.

The proliferation of vascular smooth muscle cells is controlled by specific growth factors and cytokines acting in paracrine networks. Macrophage products such as the platelet-derived growth factor and interleukin 1 promote smooth muscle proliferation and are released in the arterial wall during atherosclerosis and repair processes. T lymphocytes are also present in vascular tissue, but their role in vascular growth control in vivo has been unclear. We now demonstrate that rats in which T lymphocytes have been eliminated by a monoclonal antibody develop larger proliferative arterial lesions after balloon-catheter injury. Larger lesions also develop in athymic rnu/rnu rats that lack T lymphocytes, when compared with rnu/+ littermates with normal T-cell levels. Finally, injection of the lymphokine interferon gamma inhibits smooth muscle proliferation and results in smaller lesions compared with controls injected with buffer alone. These results indicate that T lymphocytes modulate smooth muscle proliferation during vascular repair. We propose that T lymphocytes may play an important, immunologically nonspecific role in tissue repair processes.

Animals↗
PubMed1991

Cerebral oxygen metabolism and cerebral blood flow in man during light sleep (stage 2).

We measured cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) during light sleep (stage 2) in 8 young healthy volunteers using the Kety-Schmidt technique with 133Xe as the inert gas. Measurements were performed during wakefulness and light sleep as verified by standard polysomnography. Unlike our previous study in man showing a highly significant 25% decrease in CMRO2 during deep sleep (stage 3-4) we found a modest but statistically significant decrease of 5% in CMRO2 during stage 2 sleep. Deep and light sleep are both characterized by an almost complete lack of mental activity. They differ in respect of arousal threshold as a stronger stimulus is required to awaken a subject from deep sleep as compared to light sleep. Our results suggest that during non-rapid eye movement sleep cerebral metabolism and thereby cerebral synaptic activity is correlated to cerebral readiness rather than to mental activity.

Adult↗