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Biomedical subjects

H Nilsson

Publications and source records attributed to H Nilsson.

At least 73 records · Page 4Linked to original sources
PubMed1996

Noradrenaline-induced depolarization is smaller in isobaric compared to isometric preparations of rat mesenteric small arteries.

The hypothesis was tested that wall tension can influence the membrane potential response to noradrenaline (NA) using isometric and isobaric vessel preparations of rat mesenteric small arteries. The resting membrane potential was significantly less negative in the isobaric (-49.7+/-0.5 mV, S.E.M., n=12 vessels) compared to the isometric preparation (-56.1+/-0.7 mV, n=10), although there was no difference in wall tension. The depolarization induced by 10(-5) M NA was 2.6-fold smaller in the isobaric preparation, where wall tension decreased, compared to the isometric preparation, where wall tension increased. Since wall tension decreases under isobaric conditions, but increases under isometric conditions, the latter finding can be explained by assuming that part of the NA-induced membrane potential change is wall tension dependent.

Animals↗
PubMed1996

The alpha rhythm in the electroencephalogram: a theory based on a neurophysiological model.

A column in the cerebral cortex is made up of a group of neurons and is considered to be a functional unit. Previous work has suggested that a column has two separate levels of activity, and that only a few of the columns are at the high level of activity simultaneously. To keep this number within proper limits, it is necessary to have a regulating system that reduces the cortical excitability when the number tends to increase, and vice versa. In the present paper, it is proposed that these changes up and down in the excitability can explain the generation of the alpha rhythm in the electroencephalogram. Preliminary results show that a normal alpha rhythm of about 10 Hz can be generated when the number of columns with high activity is shifting between four and five. The duration of the high activity of a column is around 450 ms.

Alpha Rhythm↗
PubMed1996

Factors of importance to Doppler indices of left ventricular filling in 50-year-old healthy subjects.

Age is an important determinant of Doppler indices of left ventricular diastolic filling in normal subjects. To define reference values and factors of importance to Doppler indices of left ventricular filling in subjects of similar age, 58 men and 76 women aged 50 years underwent Doppler echocardiography. All those taking part in the study were healthy. When gender was analysed in a multivariate model it showed a significant independent correlation with the peak velocity of early diastolic filling (E wave) (P < 0.001) and the early to atrial peak velocity (E/A) ratio (P < 0.01). The peak E wave velocity was 0.75 +/- 0.11 m.s-1 vs 0.66 +/- 0.10 m.s-1 (P < 0.001) and the E/A ratio was 1.24 +/- 0.25 vs 1.14 +/- 0.20 (P < 0.05) in women and men, respectively. In multivariate analyses, heart rate, diastolic blood pressure and body mass index correlated independently with the E/A ratio in women (P < 0.001 for all), whereas in men, heart rate, diastolic blood pressure, body mass index and left ventricular diameter correlated independently with the E/A ratio (P < 0.001 for all). Doppler measurements of left ventricular filling in 50-year-old healthy subjects showed a wide variation and were significantly associated with heart rate, diastolic blood pressure, body mass index and gender.

Blood Pressure↗
PubMed1995

Simultaneous videoradiography and pharyngeal solid state manometry (videomanometry) in 25 nondysphagic volunteers.

Recent technological advances in manometry, including solid state transducers and computerized analysis, allows for reliable interpretation of intraluminal pharyngeal pressures. Simultaneous videoradiography (barium swallow) provides fluoroscopic control of the manometric sensors (videomanometry), thereby eliminating the uncertainty of sensor dislocation during laryngeal elevation. This is the first study describing normal manometric parameters in videomanometry during barium swallow. Seven manometric parameters and six videoradiographic parameters were analyzed. We included 25 nondysphagic volunteers with normal videoradiographic parameters in the study. The examination was performed in an upright physiologic position during 10-ml barium and dry swallows. Mean resting pressure in the upper esophageal sphincter was 89.6 +/- 32.6 (+/- 2 SD) mmHg. Mean residual pressure during relaxation of the upper esophageal sphincter was 7.2 +/- 8.0 (+/- 2 SD) mmHg during barium swallow and 3.8 +/- 6.2 (+/- 2 SD) mmHg during dry swallow. The mean duration of upper esophageal sphincter relaxation was 601 +/- 248 (+/- 2 SD) msec. The mean peristaltic contraction of the upper esophageal sphincter was 253.8 +/- 142.8 (+/- 2 SD) mmHg. Fourteen (56%) of the 25 had a measurable intrabolus pressure (mean 33.2 +/- 17.3 mmHg) at the level of the inferior pharyngeal constrictor. A specific finding was discovered when the epiglottis tilts down hitting the manometric sensor. This epiglottic tilt was identified in 7 subjects (28%) and caused pressures of around 600 mmHg. A standardized manometric technique is important in videomanometry, and normal values as described in this study are essential in clinical use.

Adult↗
PubMed1995

Autonomic nerve dysfunction in patients with bolus-specific esophageal dysmotility.

The pathogenetic mechanisms causing esophageal dysmotility is not well understood. We examined 13 patients with solid bolus dysphagia in a radiologic barium study including the swallowing of a 14-mm tablet. In all 13 patients the tablet was caught in the proximal or midesophagus. In 8 patients, the entrapment was associated with symptoms (Group 1) whereas in 5 patients (Group 2), no symptoms were reported. All 13 patients together with a control group of 56 healthy, nondysphagic subjects were tested for autonomic nerve function. Autonomic nerve function tests included registration of electrocardiographic R-R interval variation during deep breathing test (E/I ratio), a test of parasympathetic, vagal, nerve function. The results showed that the E/I ratio was significantly lower in patients with symptoms of bolus-specific esophageal dysmotility (-2,19 [1.76]) (median [interquartile range]) compared with patients without symptoms (0.05 [2, 87], p = 0.0192) and controls (-0.25 [1.26], p = 0.0009). In conclusion, symptomatic bolus-specific esophageal dysmotility is associated with vagal nerve dysfunction.

Adolescent↗
PubMed1995

Oral function test for monitoring suction and swallowing in the neurologic patient.

Disturbances in swallowing are common in neurologic disease but difficult to evaluate in the clinical setting. Fundamental variables such as bolus volume, swallow capacity (volume ingested over time), and the relation between ingestion and time for important events in oral and pharyngeal swallowing have not been sufficiently studied. We therefore employed a composite method for monitoring oral and pharyngeal swallowing function: the test of Repetitive Oral Suction Swallow (the ROSS test). The technical details are described as well as preliminary results from a pilot study of 20 healthy subjects and 5 patients with neurologic swallowing impairment. The correlation with respect to time sequences for major events in bolus ingestion and oral processing as monitored by the ROSS test and by videoradiography is explained. With this simple and rapid bedside test, the immediate and long-time result of therapeutic interventions in dysphagic patients may be monitored.

Adult↗
PubMed1995

Prospective study of autonomic nerve function in type 1 and type 2 diabetic patients: 24 hour heart rate variation and plasma motilin levels disturbed in parasympathetic neuropathy.

To clarify the impact of autonomic neuropathy in diabetic patients, we have conducted a prospective study of 58 Type 1 and 51 Type 2 diabetic patients (investigated at baseline, after 4, and after 7 years). In Type 1 diabetic patients, the sympathetic nerve function (orthostatic acceleration and brake indices) and in Type 2 patients, parasympathetic nerve function (R-R interval variation; E/l ratio) deteriorated during 7 years of prospective observation. Symptoms of autonomic neuropathy were associated with signs of autonomic neuropathy (low brake indices) in Type 1 but not in Type 2 diabetic patients. In the latest assessment 24 h ECG recording was performed and blood samples assayed for neuropeptide Y (NPY) and motilin were obtained. Type 1 diabetic patients with parasympathetic neuropathy (abnormal E/l ratio) showed significantly lower SD value (less variation in the R-R intervals; 29 [17] vs 50 [16], [mean (interquartile range)]; p = 0.001) and higher postprandial plasma motilin values (70 [20] pmol l-1 vs 50 [15] pmol l-1; p < 0.01) than patients with normal parasympathetic nerve function. In Type 2 diabetic patients, sympathetic neuropathy (low brake indices) was associated with an increased frequency of ventricular extra systolic beats during 24 h ECG recording (rs = 0.65; p < 0.01). Postprandial plasma NPY levels were not associated with disturbed autonomic nerve function.

Adolescent↗
PubMed1995

Thermal aspects of vehicle comfort.

The combined thermal effects of convection, radiation and conduction in a vehicle compartment need special measuring equipment accounting for spatial and temporal variations in the driver space. The most sophisticated equipment measures local heat fluxes at defined spots or areas of a man-shaped manikin. Manikin segment heat fluxes have been measured in a variety of vehicle climatic conditions (heat, cold, solar radiation etc.) and compared with thermal sensation votes and physiological responses of subjects exposed to the same conditions. High correlation was found for segment fluxes and mean thermal vote (MTV) of subjects for the same body segments. By calibrating the manikin under homogenous, wind still conditions, heat fluxes could be converted (and normalised) to an equivalent homogenous temperature (EHT). Regression of MTV-values on EHT-values was used as basis for the derivation of a comfort profile, specifying acceptable temperature ranges for 19 different body segments. The method has been used for assessment of the thermal climate in trucks and crane cabins in winter and summer conditions. The possibility for spatial resolution of thermal influences (e.g. by solar radiation or convection currents) appeared to be very useful in the analysis of system performance. Ventilation of driver's seats is a technical solution to reducing insulation of thigh, seat and back areas of the body. Constructions, however, may vary in efficiency. In one system seat ventilation allowed for almost 2 degrees C higher ambient conditions for unchanged general thermal sensation, in addition to the pronounced local effect. In a recent study the effects of various technical measures related to cabin design and HVAC-systems have been investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Conditioning↗
PubMed1994

Finger cooling by contact with cold aluminium surfaces--effects of pressure, mass and whole body thermal balance.

Finger skin temperature change during contact with a cold aluminium surface was studied in 20 subjects (10 men and 10 women). Contact pressure (0.1 N, 5.9 N and 9.8 N), contact material mass (large one, mass 3559 g, small one, mass 108 g), surface temperatures (-7 degrees C, 0 degree C, +7 degrees C) and whole body thermal balance were controlled as independent factors. The contact experiments were performed in a small chamber and only the first section of the index finger of the left hand was in contact with the aluminium surface. The results indicated that all the factors studied had significant effects on the contact skin temperature change with time. The study confirmed that a modified Newtonian model with two components can accurately describe the contact skin temperature change with time. The study resulted in three predictive models for critical skin temperature when in contact with cold aluminium. The results indicated that metal surfaces in contact with bare hands should not be below 4 degrees C surface temperature. Lower temperatures require insulating material or the wearing of protective gloves.

Adult↗
PubMed1994

Pharyngeal solid-state manometry catheter movement during swallowing in dysphagic and nondysphagic participants.

RATIONALE AND OBJECTIVES: The movements of the soft palate and the larynx are crucial in pharyngeal manometry because of the potential risk of manometry sensor dislocation. METHODS: Twenty dysphagic patients and 20 nondysphagic volunteers were examined with simultaneous videoradiography and intraluminal pharyngeal solid-state manometry. The movements of the manometric sensors were analyzed from lateral videorecording. RESULTS: Two different types of catheter movement were found. The sensor in the upper esophageal sphincter (UES) could either be lifted cranially during the closure of the soft palate (type 1) or stay unaltered in the sphincter until the beginning of the laryngeal elevation and then follow the sphincter cranially during laryngeal elevation with no previous response to soft palate closure (type 2). Type 1 movement was found in eight of 20 patients but in only one of the 20 volunteers. The resting pressure of the upper esophageal sphincter was significantly higher in type 2 (P = 0.004). Nineteen of the 20 patients with a high resting pressure of the UES (83+ mm Hg) were found to have the type 2 movement. CONCLUSION: High resting pressure in the UES permitted the sphincter to grasp the manometry catheter and caused the sensor to follow the cranial movement during laryngeal elevation. Sensor movement is important during pharyngeal manometry, and sensor dislocation out of the sphincter can be misinterpreted as sphincter relaxation. Simultaneous videoradiography provides control of sensor positioning and allows for correction.

Adult↗
PubMed1994

Laser-induced fluorescence in malignant and normal tissue in mice injected with two different carotenoporphyrins.

Laser-induced fluorescence (LIF) was used to characterise the localisation of an intravenously administered trimethylated carotenoporphyrin [CP(Me)3] and a trimethoxylated carotenoporphyrin [CP(OMe)3] in an intramuscularly transplanted malignant tumour (MS-2 fibrosarcoma) and healthy muscle in female Balb/c mice, 3, 24, 48 and 96 h post injection. The fluorescence was induced with a dye laser pumped by a nitrogen laser, emitting light at 425 nm. The fluorescence spectra were recorded in the region 455-760 nm using a polychromator equipped with an image-intensified CCD camera. The tumour/peritumoral muscle ratio was about 5:1 for CP(Me)3 and about 6:1 for CP(OMe)3 in terms of the background-free fluorescence intensity, which peaked at about 655 nm. By including the endogenous tissue fluorescence, the contrast was further enhanced by a factor of approximately 2.

Animals↗
PubMed1994

Renin-angiotensin system in neonatal rats: induction of a renal abnormality in response to ACE inhibition or angiotensin II antagonism.

In experiments designed to analyze cardiovascular structure in response to antihypertensive therapy with an ACE inhibitor, we decided to start very early in life with the aim to prevent blood pressure increases and the development of vascular structural changes. In these treated groups of rats we unexpectedly observed that after they were weaned, their water consumption and urine volume, respectively, increased substantially. The present study was designed to determine if inhibition of the renin-angiotensin system produced similar effects in different strains of rats, and focused on characterizing the abnormal fluid balance occurring as a consequence to neonatal treatment with ACE inhibitors or angiotensin II blockers. Three-day-old Wistar Kyoto (WKY), Wistar (WR) and spontaneously hypertensive rats (SHR) were given either saline, enalapril, captopril, losartan and the AT2 blocker, PD123319, in the same amount of volume for 20 days. Treatment was stopped and rats were examined with regard to renal morphology at 4, 14 and 30 weeks of age. In addition, water consumption, urine volume, urine electrolytes and osmolality were analyzed at 14 weeks of age, that is, 10 weeks off treatment. Early treatment with the ACE inhibitors, enalapril and captopril, and the AT1 blocker, losartan, but not the AT2 blocker, PD 123319, in the SHR and in the normotensive strains WKY and WR produced persistent, irreversible histopathological renal abnormalities in adult life, long after the rats had been taken off treatment. These abnormalities consisted of mainly cortical tubulointerstitial inflammation, various degrees of papillary atrophy and pelvic dilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin I↗
PubMed1994

Cooling responses of finger in contact with an aluminum surface.

Skin temperature (T sk) changes and subjective sensations of bare fingers touching a cold aluminum surface were determined in 25 subjects (12 female and 13 male). An 11-cm aluminum cube was placed in a mini-chamber, where chamber air and an aluminum cube were simultaneously cooled to -14, -5, and -1 degrees C, respectively. Subjects inserted their right hands into the chamber and pressed on the cube surface with three fingers with a force of 9.81 N (1 Kp). Exposure lasted until finger-skin temperature reached 0 degree C or was voluntarily ended by the subject. Regression equations with two exponential components were used to describe the relationship between T sk and exposure time. The short time constant (< 1 second) for the first part of the cooling curve is assumed to represent primarily thermocouple dynamics. The long time constant (> 20 seconds) for the second part of the cooling curve is interpreted as representing the rate of heat transfer from the tissues of the finger itself. Gender and cube-surface temperature had no significant effect on any of the time constants. Thermal sensation and pain sensation lacked a good correlation with the contact and T sk and T sk change.

Adult↗
PubMed1994

Growth factor induced mitogenic effects and inositol phosphate responses in primary hepatocyte cultures from normal rat liver and rat liver nodules.

In our studies of normal and neoplastic growth regulation, we have compared growth factor induced second messenger response and mitogenic activity in a rat hepatocarcinogenesis model. Inositol phosphate (IP) turnover was measured by incubating the cells with [3H]inositol and stimulating them with either epidermal growth factor, diferric transferrin, ferricyanide, vasopressin, norepinephrine, angiotensin II or bombesin for 2 min. The IPs formed were separated on HPLC. Mitogenic responses were monitored by bromodeoxyuridine uptake and labeling index. IP turnover was stimulated by vasopressin, norepinephrine and angiotensin II in both normal and nodular cells, but not by the other four agonists tested. The IP response was somewhat lower in cells from liver nodules. All compounds except bombesin were mitogenic to both nodular cells and cells from normal rats of different ages, with epidermal growth factor inducing the largest mitogenic response. Bombesin, on the other hand, had only a minor effect on normal cells, but induced a pronounced mitogenic response in nodular cells. In normal rats, the cells' ability to respond to growth stimulation decreased with increasing rat age. In this respect, nodular cells behaved in a way more like young normal cells than their age-matched controls. Taken together, these data support the view of liver nodules being a more autonomous cell population, with increased sensitivity to growth factors and possibilities for autocrine growth stimulation.

Animals↗
PubMed1994

An experimental manometric study simulating upper esophageal sphincter narrowing.

RATIONALE AND OBJECTIVES: Elevated intrabolus pressure above a pharyngeal narrowing has been postulated as an important finding in patients with cricopharyngeal bars. To elucidate the significance of intrabolus pressure around lumen narrowings in the pharynx, intraluminal pressure characteristics were evaluated in a laboratory model simulating upper esophageal sphincter narrowing. METHODS: Intraluminal solid-state manometry was performed in an experimental model in which variable narrowing was created in an expandable balloon simulating the pharyngeal walls. RESULTS: Intrabolus pressure was dependent on the position of the manometric sensor, degree of lumen narrowing, bolus volume, flow rate, and fluid viscosity. CONCLUSIONS: Elevated intrabolus pressure is an important finding. Intrabolus pressure is dependent on many parameters, and hence, is difficult to evaluate. If results found with this model hold true in patients, manometric sensor positioning is crucial, and concurrent fluoroscopy is highly recommended to achieve a standardized manometric technique in pharyngeal manometry.

Deglutition↗
PubMed1994

Diabetes mellitus but not impaired glucose tolerance is associated with dysfunction in peripheral nerves.

To clarify whether long-term impaired glucose tolerance (IGT) is associated with dysfunction of peripheral and autonomic nerves, age-matched men with IGT and diabetes mellitus were followed prospectively for 12-15 years, when peripheral and autonomic nerve function was assessed. The patients comprised four subgroups: (1) 51 IGT subjects (duration of IGT at least 12-15 years); (2) 35 diabetic patients, with IGT 12-15 years ago, who later developed diabetes; (3) 34 diabetic patients, duration of diabetes at least 12-15 years; and (4) 62 age-matched non-diabetic control subjects. Mean age of the whole study population was 61 +/- 2 years (mean +/- SD), not different in the four groups. Peripheral nerve function tests included nerve conduction velocities, amplitudes, distal latencies, F-reflexes, and sensory perception thresholds for heat, cold, and vibration. Autonomic nerve function tests included the heart rate reaction during deep breathing (expiration to inspiration ratio) and to tilt (acceleration and brake indices). Despite 12-15 years of IGT, peripheral nerve function did not differ between IGT and control subjects, whereas autonomic nerve function deviated; an abnormal expiration to inspiration ratio (a sign of vagal nerve dysfunction) was significantly more common (15/51 versus 5/62; p < 0.01) in IGT than in control subjects. Diabetic patients (groups 2 and 3) showed lower conduction velocities (in general 2-4 m s-1 lower) than IGT and control subjects in all tested nerves. In conclusion, diabetes but not IGT, is associated with peripheral nerve dysfunction.

Age Factors↗