Biomedical subjects

Henry Svensson

Publications and source records attributed to Henry Svensson.

9 recordsLinked to original sources

PubMed2006

The influence of wavelength and probe configuration on findings of a skin vasoconstriction test when using laser Doppler perfusion devices.

The aim of this study was to establish the degree to which a standardized test based on laser Doppler blood flow measurement is dependent on the particular equipment set-up being used. For this purpose, we examined finger skin blood flow with laser Doppler instruments in 20 healthy subjects. In laser Doppler perfusion monitoring (LDPM), we used a custom-made probe with two detecting fibers placed 0.25 and 1.2 mm from the illuminating fiber, respectively, and two laser Doppler perfusion imagers (LDPI) with a wavelength of 632.8 nm and 780 nm, respectively. Warming of the hand was achieved with a Peltier element, and reflex vasoconstriction was induced by immersing the other hand for 3 min into a water bath kept at 15 degrees C. As a measure for the change in skin blood flow, a vasoconstriction index (VAC: cooling/before cooling) was calculated and used for the comparison of the different devices. VAC values gathered around 0.6 for all devices. However, LDPI with a wavelength of 632.8 nm showed a slightly higher VAC index, and the difference was significant. We conclude that using a standardized test is the most appropriate for monitoring changes in blood flow rather than recording and comparing discrete values in intermittent recordings. Although a difference was noted when comparing the devices, different fiber separations and wavelengths seem then to be of little consequence.

Adult↗

PubMed2004

Grisel syndrome after velopharyngoplasty.

We describe two patients with Grisel syndrome (atlantoaxial dislocation) after velopharyngoplasty. One required open fixation, while the other was treated with closed reduction and skull traction. Both patients recovered well after long-term follow-up. Early detection and appropiate treatment improve the prognosis.

Atlanto-Axial Joint↗

PubMed2004

Sympathetic and parasympathetic neuropathy are frequent in both type 1 and type 2 diabetic patients.

OBJECTIVE: The aim of this study was to evaluate the frequency of sympathetic versus parasympathetic neuropathy among type 1 and type 2 diabetic patients. RESEARCH DESIGN AND METHODS: There were 43 patients with type 1 and 17 with type 2 diabetes who were investigated. Sympathetic nerve function was assessed by measurement of the vasoconstriction (VAC) index by laser Doppler perfusion imaging of a locally heated finger followed by indirect cooling. Parasympathetic nerve function was assessed by R-R interval variation during deep breathing as measured by the expiration/inspiration (E/I) ratio. Results were expressed as age-corrected z scores in SD; VAC index >1.64 SD and E/I ratio <-1.64 SD were considered abnormal. RESULTS: VAC index was abnormal in 40% with type 1 and 41% with type 2 diabetes, whereas the E/I ratio was abnormal in 42% with type 1 and 65% with type 2 diabetes. There was a clear association between VAC index and E/I ratio among type 1 (rs=0.525; P=0.0002) but not among type 2 (rs=0.10) diabetic patients. Among type 2 diabetic patients, the degree of dysfunction was most severe regarding parasympathetic function (P=0.0167). CONCLUSIONS: Sympathetic and parasympathetic neuropathy were frequent in both type 1 and type 2 diabetic patients. However, there was a difference between the two types of diabetes. Sympathetic and parasympathetic nerve functions correlated in type 1 but not in type 2 diabetic patients. The explanation for this discrepancy might be that parasympathetic nerve function was most severely affected among type 2 diabetic patients.

Diabetes Mellitus, Type 1↗

PubMed2003

Laser Doppler perfusion monitoring of skin blood flow at different depths in finger and arm upon local heating.

The purpose of the study was to elucidate the vasodilatory response to local heating of the skin at two depths in two locations. To accomplish this, we measured skin blood flow in 12 healthy subjects using laser Doppler perfusion monitoring. A probe with two fibers separated 0.14 mm (superficial) and 0.25 mm (deeper) from the illuminating fiber was first attached to the distal phalanx of the index finger and thereafter to the dorsal forearm skin. Local heating was caused with a thermostatic probe holder set at 40 degrees C. We studied the perfusion value and its two components, velocity and concentration. All registrations were also subjected to frequency analysis. Laser Doppler values were generally higher in the fingertip than in forearm skin. Heating caused increased values at both locations. Concentration increased relatively more than velocity and this was most obvious in the forearm. There were only slight differences in response between superficial and deeper vascular components. Frequency analysis revealed a peak in perfusion and velocity obviously related to the heartbeat. Movement of the column of blood thus reached the peripheral vascular network without changing concentration. We conclude that local heating increases skin blood flow in fingertip and forearm skin by different adjustments of blood cell concentration and velocity, presumably depending on differing vascular anatomy and physiological control, but differences are of a rather minor character. Furthermore, responses differ just slightly in superficial compartments as probed with fibers separated up to 0.25 mm.

Adult↗

PubMed2003

Involvement of sympathetic nerve activity in skin blood flow oscillations in humans.

We have used the wavelet transform to evaluate the time-frequency content of laser-Doppler flowmetry (LDF) signals measured simultaneously on the surfaces of free microvascular flaps deprived of sympathetic nerve activity (SNA), and on adjacent intact skin, in humans. It was thereby possible to determine the frequency interval within which SNA manifests itself in peripheral blood flow oscillations. The frequency interval from 0.0095 to 2 Hz was examined and was divided into five subintervals: I, approximately 0.01 Hz; II, approximately 0.04 Hz; III, approximately 0.1 Hz; IV, approximately 0.3 Hz; and V, approximately 1 Hz. The average value of the LDF signal in the time domain as well as the mean amplitude and total power in the interval from 0.0095 to 2 Hz and amplitude and power within each of the five subintervals were significantly lower for signals measured on the free flap (P < 0.002). The normalized spectral amplitude and power in the free flap were significantly lower in only two intervals: I, from 0.0095 to 0.021 Hz; and II, from 0.021 to 0.052 Hz (P < 0.05); thus indicating that SNA is manifested in at least one of these frequency intervals. Because interval I has recently been shown to be the result of vascular endothelial activity, we conclude that we have identified SNA as influencing blood flow oscillations in normal tissues with repetition times of 20-50 s or frequencies of 0.02-0.05 Hz.

Adrenergic Fibers↗

PubMed2002

Plasma proteins in a standardised skin mini-erosion (I): permeability changes as a function of time.

BACKGROUND: A standardised technique using a suction-induced mini-erosion that allows serial sampling of dermal interstitial fluid (IF) for 5 to 6 days has been described. In the present study, we studied permeability changes as a function of time. METHODS: We examined IF concentrations of total protein concentration and the concentration of insulin (6.6 kDa), prealbumin (55 kDa), albumin (66 kDa), transferrin (80 kDa), IgG (150 kDa) and alpha-2-macroglobulin (720 kDa) as a function of time, using an extraction pressure of 200 mmHg below atmospheric. RESULTS: At 0 h after forming the erosion, mean total IF protein content (relative to plasma) was 26 +/- 13% (SD). For the individual proteins, the relative mean concentrations were 65 +/- 36% for insulin, 48 +/- 12% for albumin, 30 +/- 19% for transferrin, 31 +/- 15%for IgG and 19.5 +/- 10% for alpha-2-macroglobulin. At 24 h, the total IF protein content was higher than at 0 h (56 +/- 26% vs 26 +/- 13%; p < 0.05, diff: 115%), as were some of the individual protein concentrations: prealbumin (50 +/- 24 vs 25 +/- 13%; p < 0.05), albumin (68 +/- 21 vs 48 +/- 12%; p < 0.05) and IgG (55 +/- 30 vs 31 +/- 15%; p = 0.05). ln the interval 24 h to 96 h the concentrations were relatively unchanged. CONCLUSIONS: The results indicate that fluid sampled at 0 h after forming the erosion represents dermal IF before the full onset of inflammation. From 24 h onward, the sampled fluid reflects a steady state of increased permeability induced by inflammation. This technique is promising as a tool for clinically sampling substances that are freely distributed in the body and as a model for studying inflammation and vascular permeability.

Adult↗

PubMed2002

Plasma proteins in a standardised skin mini-erosion (II): effects of extraction pressure.

BACKGROUND: A standardised suction technique has been used to sample plasma proteins in dermal interstitial fluid (IF) serially for 5 to 6 days from a suction-induced skin mini-erosion. Increased protein concentrations ascribed to inflammation have been shown from day 1 onward. In this study, we assessed the effect of two different extraction pressures on IF sample composition. METHODS: Total protein concentration and the concentrations of insulin, prealbumin, albumin, transferrin, IgG and alpha-2-macroglobulin were assessed daily in healthy volunteers. Samples were extracted at 50 mmHg and 200 mmHg below the atmospheric. RESULTS: At 0 h after forming the erosion, mean total IF protein content (relative to plasma) was lower in the samples extracted at -200 mmHg than at -50 mmHg (26 +/-13% (SD) vs 48 +/-9.8%; p < 0.05). There were no significant differences at 24, 48, 72 or 96 h. Of the individual proteins, expressed as area units (AU) for area under the curve (AUC) from 0-96 h, albumin was lower in IF sampled at -200 mmHg (2.49 +/- 0.68 vs 3.08 +/- 0.36 AU; p < 0.05), as was transferrin (1.91 +/- 0.52 vs 2.40 +/- 0.42 AU; p < 0.05). Extraction volumes were significantly higher at -200 mmHg (AUC diff: 60%; p < 0.05). CONCLUSIONS: Samples of IF extracted at 0 h at -200 mmHg contained lower protein concentrations, indicating an increased water fraction and an intact sieve function of the vascular wall. The difference in protein concentration extracted at higher and lower pressure from 24 h onward was less pronounced. Lower pressure should be used to sample substances of greater molecular size.

Blood Proteins↗

PubMed2002

Otitis media and feeding with breast milk of children with cleft palate.

The purpose of the present study was to analyse the incidence of acute and secretory otitis media (OM), and feeding with breast milk, and the use of a grommet in children with a cleft palate (CP/CLP) or cleft lip (CL), compared with controls. A total of 84 children between 6 and 10 years of age were studied. The CP/CLP group consisted of 48 children with an isolated cleft palate (n = 28), or a cleft lip and palate (n = 20). The CL group consisted of 15 children with an isolated cleft lip. The controls were 21 children without clefts. Children with CP/CLP had acute OM significantly more often than children without clefts (43/48 compared with 10/21), and secretory OM (40/48 compared with 4/21), despite the use of grommets. CP/CLP children were breast fed for a mean of 2.8 months (range 0-13), compared with 3.6 months (0-12) for CL, and 7.5 (0-24) months for controls. There was a significant correlation during the first 18 months of life between longer duration of feeding with breast milk and a lower incidence of acute and secretory OM in the three study groups combined. The incidence of otitis media was not affected by care in a day centre, having a sibling attending a day care centre, or by the family's medical history. Despite cleft repair and early treatment with grommets, both secretory and acute OM are common among children with cleft palate, presumably as a result of their eustachian tube dysfunction. The present study suggests that premature cessation of feeding with breast milk may contribute to an increased incidence of acute and secretory OM.

Acoustic Impedance Tests↗

PubMed2002

Self-concept and introversion in adolescents with cleft lip and palate.

The purpose of this study was to investigate if adolescents with cleft lip, or palate, or both (CLP), have an altered self-concept, and to assess their degree of introversion, compared with a control group. The CLP group consisted of 55 adolescents (aged 17-20 years) and the control group consisted of 31 adolescents (16-19 years). The Tennessee Self Concept Scale (TSCS) was used to measure the subjects' self-concept, while the Eysenck Personality Questionnaire Inventory (EPQ-I) was used to measure introversion. The results indicate that those with CLP have a normal or even a high self-concept, and no signs of introversion.

Adolescent↗