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Biomedical subjects

P Neuvonen

Publications and source records attributed to P Neuvonen.

At least 19 recordsLinked to original sources
PubMed2005

Determination of soil adhesion to plastic surfaces using a radioactive tracer.

A quantitative radiochemical test procedure was developed for investigating soil adhesion on polyvinyl chloride (PVC) model materials containing different plasticizers (DOP and Hexamoll) and commercial flooring materials. A repeatable test procedure was developed, including soiling and cleaning with a Mini Cleanability Tester. Three soils all containing 51Cr emitting gamma radiation were used. The materials were subjected to successive soiling and cleaning cycles in order to generate soil accumulation. The type and amount of plasticizer appeared to affect soil adhesion on plastic model materials.

Journal Article↗
PubMed1997

Enalaprilat decreases plasma endothelin and atrial natriuretic peptide levels and preload in patients with left ventricular dysfunction after cardiac surgery.

OBJECTIVE: To study the acute effects of angiotensin-converting enzyme inhibition by intravenous enalaprilat infusion in patients with left ventricular dysfunction after cardiac surgery. DESIGN: Prospective, consecutive sample, before-after trial. SETTING: Surgical intensive care unit in a tertiary care university hospital. PARTICIPANTS: Eight patients with left ventricular dysfunction after cardiac surgery. Patients were defined as having left ventricular dysfunction if the pulmonary capillary wedge pressure persisted above 18 mmHg in spite of conventional vasoactive medication (inotropic or vasodilating and diuretic drugs) and intermittent mandatory ventilation during the first postoperative week. INTERVENTIONS: Enalaprilat was infused initially at 1 mg/ hour. The rate was doubled every 30 minutes until pulmonary capillary wedge pressure decreased at least 20% or until a maximum total dose of 10 mg was achieved. MEASUREMENTS AND RESULTS: Central hemodynamics, systemic oxygenation, and hormonal regulation of circulation (plasma renin activity, plasma endothelin, atrial natriuretic peptide, norepinephrine, epinephrine, and vasopressin concentrations, serum angiotensin-converting enzyme activity, and serum levels of aldosterone) were assessed at baseline before enalaprilat infusion, and repeatedly over 2 hours after the infusion. Enalaprilat infusion (median dose, 2.0 mg; infusion time, 48 minutes) caused a significant decrease in pulmonary capillary wedge pressure (p = 0.004), lasting until the end of the 2 hours' follow-up. This coincided with inhibition of serum angiotensin-converting enzyme activity (p < 0.001), an increase in plasma renin activity (p = 0.022), and decreases in plasma endothelin (p = 0.035), atrial natriuretic peptide (p = 0.005), and serum aldosterone (p = 0.001) concentrations. Cardiac output, venous admixture, and oxygen delivery and consumption remained unchanged. CONCLUSIONS: Adding enalaprilat to conventional therapy makes it possible to unload the left ventricle and to relieve overt neurohormonal activation temporarily while maintaining cardiac function and systemic oxygenation.

Adult↗
PubMed1997

Comparison of cyclophilin binding assay and radioimmunoassay in monitoring of blood cyclosporine.

Cyclosporine binds with cyclophilin, an abundant protein found in almost all tissues, and the resulting complex interacts with calcineurin diminishing T-cell activation. Cyclophilin can be regarded as a cellular "receptor" for cyclosporine. Measuring cyclosporine binding to cyclophilin may offer a link between pharmacokinetics and pharmacodynamics that could improve monitoring of cyclosporine therapy. The authors investigated the feasibility of the cyclophilin binding assay and compared the results with a standard specific monoclonal radioimmunoassay in 100 blood samples taken for therapeutic drug monitoring. The results obtained with these methods were related closely with each other (r = 0.96; p < 0.001) but the mean (+/-SEM) concentrations were approximately two-fold higher in cyclophilin binding assay than in radioimmunoassay (520.4 +/- 49.9 ng/ml versus 257.7 +/- 28.6 ng/ml, respectively, p < 0.001). The shapes of the cyclosporine concentration versus time curves in two patients after a liver and heart transplantation, respectively, were similar after both methods but cyclophilin binding assay gave higher values than radioimmunoassay. Before firm conclusions on the clinical value of cyclophilin binding assay can be made, comparative studies in patients linking cyclosporine concentrations measured with cyclophilin binding assay and standard methods to the therapeutic outcome are needed.

Amino Acid Isomerases↗
PubMed1995

The role of potassium in postural hypotension: electrolytes and neurohumoral factors in elderly hypertensive patients using diuretics.

OBJECTIVE: To study the association between postural hypotension and (i) electrolyte levels and (ii) neurohumoral factors in elderly hypertensive patients using diuretics. DESIGN: Cross-sectional study of patients and controls. SETTING: The subjects were gathered from senior citizen clubs or they were referred to the study by general practitioners. The subjects were examined on a geriatric ward in Turku City Hospital. SUBJECTS: Seven subjects with postural hypotension and 13 controls. MEASUREMENTS: Plasma electrolyte levels and neurohumoral response to head-up tilt. RESULTS: There were significantly more hypokalaemic subjects in the postural hypotension group (5/7) than in the control group (1/13) (P < 0.01). The plasma potassium level was negatively correlated to plasma aldosterone (r = -0.57; P < 0.01) and renin activity (r = -0.69; P < 0.001). Subjects with postural hypotension had higher levels of noradrenaline, both supine (P < 0.05) and during tilt (P < 0.05). There were no significant differences in supine or tilt levels of plasma adrenaline, vasopressin, atrial natriuretic peptide, aldosterone and renin activity between the groups. CONCLUSION: The results suggest that potassium depletion is associated with postural hypotension in elderly hypertensive patients using diuretics. However, it is unclear whether there is a causative link between potassium depletion and postural hypotension or whether they are both caused by some other factor, e.g. volume contraction.

Aged↗
PubMed1995

Anaesthesia for microvascular surgery in children. A combination of general anaesthesia and axillary plexus block.

Nowadays, microvascular reconstructions are performed with high success rate even in small children. The combination of general anaesthesia and axillary plexus block was used in this prospective study in order to achieve optimal surgical conditions in these challenging operations. Fifteen children under eight years of age (1-8 years) were anaesthetised with a standardised anaesthesia method using a combination of general anaesthesia and axillary plexus block for microvascular toe-to-hand transfer. The duration of anaesthesia varied between 7.5-14.5 hours (mean 11 h). The difference in peripheral skin temperature was used to indicate the difference in peripheral circulation. Due to plexus block, the mean skin temperature in the operated hand was 1.4 degrees C higher than in the opposite extremity at the end of the operation. In the early postoperative phase the temperature difference increased to 4.8 degrees C (P < 0.01) due to vasoconstriction in the control hand. The mean temperature in the transplant was 33.3 +/- 2.4 degrees C at the end of the operation. Primary microvascular results were good in all but two children who needed reoperations. All of the transfers survived. The mean central temperature increased progressively during the operation from 36.2 degrees C to 37.6 degrees C. One 1-year-old child developed a moderate hyperthermia of 39.1 degrees C. According to this study axillary plexus block can be combined with general anaesthesia in prolonged microvascular operations. When the effect of general anaesthesia ceased, the plexus block effectively increased peripheral circulation in the operated hand.

Anesthesia, General↗
PubMed1994

Spectral analysis of heart rate variability in evaluation of sympathetic function in elderly subjects.

Plasma concentration of noradrenaline is often used as a measure of sympathetic nervous activity. Recently, the method of spectral analysis of heart rate variability has been introduced to detect autonomic dysfunction. To examine whether spectral analysis of heart rate variability is useful in evaluating sympathetic function, changes in the heart rate variability in the low-frequency spectral band were compared with the change of plasma noradrenaline in response to head-up tilt in elderly hypertensives (n = 13) and diabetics (n = 13). In hypertensive subjects, there was an increase in relative low-frequency power (p = 0.015) and an increase in plasma noradrenaline level (p = 0.040) in response to head-up tilt. Diabetics did not show corresponding changes. There was no change in absolute low-frequency power in either group. It is concluded that spectral analysis of heart rate variability can be useful in evaluating sympathetic function in elderly subjects.

Aged↗
PubMed1994

Enalaprilat in acute intractable heart failure after myocardial infarction: a prospective, consecutive sample, before-after trial.

OBJECTIVE: To evaluate the acute effects of intravenous enalaprilat infusion in critically ill patients with intractable heart failure after acute myocardial infarction. DESIGN: Prospective, consecutive sample, before-after trial. SETTING: Medical intensive care unit in a university hospital. PATIENTS: Eight consecutive patients with intractable acute heart failure after acute myocardial infarction. All study patients continued receiving inotropic, vasodilating, and diuretic medication at a constant rate. Six patients received steady intermittent mandatory ventilation and two patients were on a continuous positive airway pressure mask during the investigation, all with constant positive end-expiratory pressure. Heart failure was defined as intractable if the pulmonary artery occlusion pressure remained > 20 mm Hg despite this conventional therapy. INTERVENTIONS: Enalaprilat was infused at a rate of 1 mg/hr until the pulmonary artery occlusion pressure decreased by > or = 20%. MEASUREMENTS AND MAIN RESULTS: Central hemodynamics, oxygenation, and hormonal regulation (plasma renin activity, plasma norepinephrine, epinephrine, endothelin, atrial natriuretic peptide, and vasopressin concentrations, serum angiotensin-converting enzyme activity, and serum concentrations of aldosterone) were assessed at baseline before enalaprilat infusion, and repeatedly during 2 hrs after the infusion. The statistical analysis was performed with analysis of variance for repeated measurements. Enalaprilat infusion (median dose 0.3 mg and infusion time 21 mins) caused significant but short-lasting decreases in pulmonary artery occlusion pressure (p = .007), mean arterial pressure (p = .003), mean pulmonary arterial pressure, and rate pressure product. These findings coincided with inhibition of serum angiotensin-converting enzyme activity, an increase in plasma renin activity, and a decrease in plasma endothelin concentrations (p = .041). Enalaprilat had no significant effects on the other hormones studied. Cardiac output and stroke volume index, venous admixture, oxygen extraction ratio, and mixed venous and arterial oxygen saturations remained unchanged. CONCLUSIONS: Adding enalaprilat to conventional therapy makes it possible to transiently relieve pulmonary congestion while maintaining cardiac function and systemic oxygenation. The decrease in plasma endothelin concentrations may have further clinical implications, because endothelin is known to have potent vasoconstricting effects on the coronary circulation and it may also contribute to the extension of myocardial infarction. Whether these observed benefits can be maintained with repeated bolus injections or with continuous infusion of enalaprilat, remains to be settled.

Acute Disease↗
PubMed1993

Itraconazole prevents terfenadine metabolism and increases risk of torsades de pointes ventricular tachycardia.

Terfenadine, a nonsedating H1-selective antihistamine, is widely used in many countries. We report pharmacokinetic results in a patient who developed a prolonged QT-interval in ECG and symptomatic torsades de pointes ventricular tachycardia as a consequence of the interaction of itraconazole and terfenadine. Both drugs were taken in the recommended doses: terfenadine 60 mg b.d. and itraconazole 100 mg b.d. Terfenadine metabolism was delayed by itraconazole, leading to an increased level of unmetabolised terfenadine. Seven weeks after the cessation of itraconazole treatment, terfenadine was rapidly metabolized to its active metabolite and did not prolong the QT-interval when given as a single provocation dose (120 mg). The findings suggest that intraconazole in therapeutic doses inhibits terfenadine metabolism. It is also possible that unmetabolised terfenadine alone, without an increased level of its active metabolite, may cause torsades de pointes. The concomitant use of terfenadine and itraconazole (and ketoconazole) should be avoided.

Adult↗
PubMed1989

The effect of continuous intravenous indomethacin infusion on bleeding time and postoperative pain in patients undergoing emergency surgery of the lower extremities.

Fifty-four orthopaedic patients were given either indomethacin (25-50 mg bolus plus infusion, 5-7.5 mg h-1) or only lactated Ringer solution intravenously over 20 h in a randomized and double-blind fashion. The study was started at the casualty department as soon as possible after the decision to operate was made. The patients were given a spinal block with bupivacaine, and the evaluation included postoperative analgesia and IVY bleeding times. Indomethacin plasma concentrations were measured and found to be at a therapeutic level throughout the study. The oxycodone dose (mean +/- s.d.) during the postoperative observation was lower in the indomethacin group (17.4 +/- 13.7 mg) than in the control group (25.6 +/- 15.6 mg) (P = 0.05). Fewer patients in the indomethacin group needed oxycodone more than once during the follow-up period (P less than 0.001). The mean IVY bleeding time was prolonged in the indomethacin group after 20 h of infusion (P less than 0.05). No abnormal bleeding was observed immediately postoperatively. However, at the end of the infusion there were more patients who bled through their bandages and casts in the indomethacin group (4/28 vs. 1/26).

Adult↗
PubMed1985

Delayed hypersensitivity skin testing of 150 volunteers. Retesting results and antibody measurements.

We studied skin test reactivity to five commonly used antigens by testing 150 healthy adults. The delayed hypersensitivity (DH) skin test is widely used to assess the immune status of patients. The battery of antigens suitable for use may vary in different countries, but the reactivity to the antigens in our population did not differ remarkably from reports of other authors. The reactivity rates were: candida 32.7%, mumps 86%, streptokinase-streptodornase (SK-SD) 70%, trichophyton 0% and tuberculin 58.7%. Sixteen of the subjects were retested after 2 weeks. Only eight of them showed unchanged reactions to all five antigens. Specific IgG antibody concentrations measured by enzyme-linked immunosorbent assay (ELISA) against each of the five antigens in the serum of 42 subjects before and after testing showed great inter-individual variation. The antibody concentration did not correlate with the DH skin test results, but the testing itself increased the production of anti-mumps- and anti-SK-SD-antibodies.

Adolescent↗
PubMed1985

Hypophosphatemia in hypercatabolic patients.

Twenty-four hypercatabolic surgical intensive care patients were treated with a daily phosphate dosage of 0.5 mmol/kg b.wt during the postoperative total parenteral nutrition (TPN). The adequacy of this regimen was evaluated by measuring the plasma phosphate concentration before and after five days of TPN. All the patients were in negative nitrogen balance throughout the study. Ten of them were hypophosphatemic at the beginning, while none was hypophosphatemic at the end of the study. Hyperphosphatemia was observed once, at the end of the study. The catabolic surgical patient receiving parenteral nutrition is at risk of hypophosphatemia, and particularly vulnerable to its consequences. A daily dosage of 0.5 mmol/kg b.wt of phosphate appeared adequate in covering the increased requirements of these patients.

Humans↗
PubMed1984

Effects of preoperative parenteral nutrition on cell-mediated immunity in malnourished patients.

Cell-mediated immunity was studied in 19 malnourished patients admitted for major abdominal surgery. Nine of them received total parenteral nutrition (TPN) before operation (the TPN group), while ten (the control group) were operated on without a period of TPN. In vitro lymphocyte proliferative responses to phytohaemagglutinin (PHA), concanavalin A (Con A) and purified protein derivative of tuberculin (PPD), were measured in whole blood cultures preoperatively, at the end of surgery and 5 days after operation. In vivo delayed skin hypersensitivity to candida, mumps, streptokinase-streptodornase and PPD was studied preoperatively and 5 days after operation. Complications in both groups were observed and recorded. Nutritional assessment was carried out by evaluating the extent of recent weight loss, the weight for height index and by measuring the arm muscle circumference (AMC), triceps skinfold thickness (TSF), the creatinine-height index (CHI) and serum albumin and prealbumin concentrations. The patient was considered to be malnourished and was included in the study, if at least three of these criteria were abnormal. In the TPN group changes in mitogen induced lymphocyte proliferative responses caused by surgery were not significant. By contrast, responses in the control group decreased significantly (P < 0.01) during surgery and most of these responses differed from the preoperative values even at the fifth postoperative day. Anergy was equally common in both groups before and after surgery. The number of infectious complications was lower in the TPN group.

Journal Article↗
PubMed1983

Prolonged impairment of cell-mediated immunity after major abdominal surgery in malnourished patients.

The effect of the nutritional status on postoperative impairment of the immune response was studied in adults undergoing major abdominal surgery. The immune function was evaluated by measuring in vitro the lymphocytic response to phytohaemagglutinin (PHA), concanavalin A (Con A) and the purified protein derivative of tuberculin (PPD) in whole blood cultures, and in vivo delayed skin hypersensitivity to candida, mumps, streptokinase-streptodornase and PPD. Nutritional assessment was carried out by evaluating recent weight loss, the weight for height index and by measuring the arm muscle circumference (AMC), triceps skinfold thickness (TSF), the creatinine-height index (CHI) and the serum concentration of albumin and prealbumin. The patient was considered malnourished, if at least three of these criteria were abnormal. The immune parameters were measured preoperatively, at the end of the surgery and five days after operation. Before the operation both malnourished and well-nourished patients had normal lymphocytic responses, but the malnourished patients had a slower recovery of immune responses after the operation and they had an increased number of postoperative complications. No significant differences in the incidence of anergy were observed between the well and malnourished patients pre or postoperatively.

Journal Article↗
PubMed1983

Hemodynamic responses to physostigmine in patients with a drug overdose.

Hemodynamic responses to physostigmine were evaluated in eight patients with coma due to overdose with mainly anticholinergic drugs (AC) and in five patients with coma due to overdose with nonanticholinergic drugs (NAC). After correction of hypovolemia, but before administration of physostigmine, AC patients had significantly lower systemic vascular resistances, slightly higher cardiac outputs, and lower mean arterial pressures than NAC patients. Physostigmine produced negligible hemodynamic and, as expected, negligible neurological changes in NAC patients. In AC patients physostigmine produced, also as expected, improved consciousness and in addition significantly increased mean arterial pressure, cardiac output, and cardiac work without significantly affecting systemic vascular resistance.

Adult↗