Biomedical subjects
Publications and source records attributed to M Toivonen.
Dosimetric methods used for interventional and diagnostic radiology are reviewed and evaluated, including terms, quantities, equipment, calibration and measurements. Measurement of local skin dose and estimation of maximum local skin dose are emphasised. Aspects related to dosimetry in computed tomography and to methods of determining organ and tissue doses are not considered.
The first sporadic cases of Fujian/411/02-lineage viruses were recorded in Finland in winter 2001-2002. The first protracted but low-intensity outbreak occurred here during the first half of 2003, and the second outbreak early in autumn 2003, after detection of sporadic influenza A cases in the summer. The calculated incidence of influenza A in the Finnish army was 515/10000 during the first outbreak and 2066/10000 during the second outbreak. During the 2003-2004 epidemic season, the isolates fell into three groups for their haemagglutinin (HA1) sequences. In groups I and II, the strains were reassortants which differed for their neuraminidase (NA) sequences from the viruses of the previous spring. Group II viruses, which predominated in Finland during the 2003-2004 season, were characterized by loss of the glycosylation site at position 126 in HA1. The relevance of this loss to the epidemiology is discussed, as well as the frequent appearance of codominant amino acid mixtures at position 151 lining the catalytic cavity of the NA. Group III viruses, genetically related to Wellington/1/2004, the drift variant predominant in 2004 in the southern hemisphere, caused some localized outbreaks in Finland towards the end of the 2003-2004 epidemic. The antigenic match between the vaccine virus (Panama/2007/99) and the Fujian-lineage epidemic viruses in winter 2003-2004 was far from optimal. Nevertheless, high levels of prevaccination and postvaccination antibodies to the predomi- nant group II virus were recorded. Lower antibody levels were detected to the group III virus, which turned out to be a herald strain that reappeared in Finland during the following epidemic season.
This article describes the European DIMOND approach to defining reference levels (RLs) for radiation doses delivered to patients during two types of invasive cardiology procedures, namely coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA). Representative centres of six European countries recorded patients' doses in terms of dose-area product (DAP), fluoroscopy time and number of radiographic exposures, using X-ray equipment that has been subject to constancy testing. In addition, a DAP trigger level for cardiac procedures which should alert the operator to possible skin injury, was set to 300 Gyxcm2. The estimation of maximum skin dose was recommended in the event that a DAP trigger level was likely to be exceeded. The proposed RLs for CA and PTCA were for DAP 45 Gyxcm2 and 75 Gyxcm2, for fluoroscopy time 7.5 min and 17 min and for number of frames 1250 and 1300, respectively. The proposed RLs should be considered as a first approach to help in the optimisation of these procedures. More studies are required to establish certain "tolerances" from the proposed levels taking into account the complexity of the procedure and the patient's size.
Dosimetry requirements and protocols for performing measurements in digital and interventional radiology are discussed. Calculated entrance surface dose (ESD) is predicted to be of increasing interest in the future, replacing direct measurement with thermoluminescence (TL) dosemeters. The quantities proposed for establishment of reference values for interventional radiology are reviewed briefly, and the methods of collecting the data required for estimation of their values by means of traditional manual and new automatic methods are compared. It is concluded that the manufacturers of X ray units can largely solve the dosimetry problems of interventional radiology in machines with fully digital control systems after they have received sufficient data on patient dosimetry requirements.
Some dosimetry instruments and products are reviewed, the main emphasis being on patient dosimetry, recommendations for accuracy in different measurement applications and the results of some intercomparisons. It seems to be a common problem that the users of the general purpose air kerma (Ka) meters, dose-area product (DAP) meters or products such as thermoluminescence (TL) dosemeters are not always able to select the correct ionisation chamber, the calibration factor of a DAP meter or the TL dosemeter material and type, respectively, for different radiation conditions. The combined DAP and Ka meters developed recently, as well as the exposure data acquisition systems designed for monitoring one or more quantities or for determining the effective dose of a complicated examination, are described briefly. The most advanced software of these systems is able to display the dose distributions for the most exposed areas of the skin, on-line.
The objective of this study was to examine the quality of life in patients with Parkinson's disease (PD) in a community-based sample (n = 228 patients) using a Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) as a measure. Associations to the variables age, age at onset, duration, clinical stage (Hoehn and Yahr), depression (Zung), and dementia (MMSE) were studied. Women scored significantly lower on five of the eight dimensions of SF-36. Depression, as measured in this study, was more common among parkinsonian women than men. Depression was the factor that was associated most significantly with the experienced quality of life, according to SF-36. With physical functioning, only the clinical stage had a more significant association than depression. To improve the quality of life in patients with PD, it is necessary to make every effort to recognize and relieve the depression of patients with PD.
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Quantitative analyses of cytoplasmic and nuclear organelle movements in living interphase cells at defined stages of differentiation are few. By phase contrast videomicroscopy and digital imaging techniques, we have traced the path of the chromatoid body (CB) and analysed its rapidly changing positions in relation to the nuclear envelope, Golgi complex and nuclear pale chromatin areas in living early spermatids of the rat. The CB had intimate interactions with the nuclear envelope and moved both in parallel and perpendicular fashion in relation to it. It had successive short contacts with the Golgi complex and nuclear pale chromatin areas. It was also seen to scan between two pale chromatin areas and it had pinocytosis-like transient engulfments during interactions with the pale chromatin. In ultrastructural analysis of snap-frozen preparations, the CB had a large contact area with the nuclear envelope with several intermediate organelles that may be involved in nucleocytoplasmic material transport. It is evident that quantitative image analysis of living cells is a powerful guide for ultrastructural analyses. The snap-freezing technique gives new possibilities for studies of structures that are sensitive to conventional fixation procedures.
Both the use of traditional fluoroscopy and the increasing use of modern digital techniques in radiology and interventional radiology demand the development of versatile computer programs for patient dose determinations. Long computing times restrict the use of Monte Carlo (MC) methods in dose monitoring applications where the radiological views change frequently. In the Organ Doses Calculation Software application (ODS-60), the phantom model is similar in principle to the Alderson-Rando (A-R) phantom, but its sex, size and shape is modified according to a particular patient. Organ and effective doses are computed online (in a few seconds) using a method similar to the traditional dose planning systems used in radiotherapy. In this paper, the new ODS-60 software is presented in detail and its capabilities are demonstrated. Software performance was determined by comparing the results with those from independent methods. In the case of a reference man-sized male, the effective dose was about 7% larger than the effective dose given in another publication. In the case of a reference woman-sized female, the disagreement with the other method was greater (33%). Anatomical differences between the phantom models (ODS-60 and MC) were found to be the main reasons for these findings. This paper shows the advantage of using a patient size- and sex-adaptable phantom for patient dose determinations; the conversion coefficient from entrance surface dose-to-effective dose ratio between male (170 cm, 85 kg) and a female (160 cm, 43 kg) varies in the range 1.5-2.
OBJECTIVE: To examine the effect of moderate alcohol intake with a meal on glucose homeostasis in diabetic patients. RESEARCH DESIGN AND METHODS: Alcohol (1 g/kg, an aperitif before, wine during, and a drink after a meal) or an equal amount of mineral water was given during a dinner. Blood glucose and insulin concentrations were measured before, during, and after the meal until the next morning. This study was conducted at the Helsinki University Hospital Metabolic Ward and the Finnish Diabetes Association Education Center. The participants in the study included 10 type I diabetic patients treated with insulin and 16 type II diabetic patients treated with diet alone or with diet and oral drugs. In each subject, we examined hypoglycemic episodes or differences in blood glucose or serum insulin concentrations between alcohol and the control study. RESULTS: In type I diabetic patients, blood glucose and insulin concentrations were virtually identical in both studies. In type II diabetic patients, alcohol slightly enhanced the meal-induced insulin secretion resulting in lower blood glucose concentrations next morning. No hypoglycemic glucose concentrations were observed in either group after alcohol ingestion. CONCLUSIONS: Moderate alcohol intake with a meal does not lead to hypo- or hyperglycemia in diabetic patients.
The effect of morphine on cold-stimulated secretion of TSH and prolactin was studied in male rats, both in acute studies and after the chronic administration of morphine for 14 days (twice a day with increasing doses). The duration of the stimulatory effect of a single dose of morphine on secretion of prolactin was shorter (less than 2 hr) than its inhibitory effect on cold-stimulated secretion of TSH (over 2 hr). In the rats pretreated with morphine, a tolerance to the depressant effect of TSH of the challenge dose of morphine was seen at 2 hr but not at 1 hr after the injection. In contrast, a tolerance to the stimulatory effect of morphine on prolactin was seen at 1 hr after the acute dose of morphine. The minor alterations of the hypothalamic amine neurotransmitters and their metabolites did not correlate with the hormonal responses or to the development of tolerance.
The effects of serotonergic activation on cold-stimulated thyrotropin (TSH) and prolactin secretion were studied in male rats. Peripheral injections of both 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT), a 5-HT1A receptor agonist, and 1-(3-chlorophenyl)piperazine (m-CPP), a 5-HT1 agonist, decreased TSH levels. The action of 8-OH-DPAT was antagonized by (+/-)-pindolol, which is known to have 5-HT1 antagonist activity, but not by metergoline or ketanserin. The action of m-CPP was antagonized by ketanserin but not by metergoline. TSH levels were not affected by a 5-HT3 receptor agonist, 2-methyl-5-HT, or by a 5-HT3 antagonist, MDL 72222. Infusion of 8-OH-DPAT into the anterior third ventricle increased TSH levels; 5-HT tended to increase TSH levels, but the effect was not significant. Inversely, infusion of 5-HT, 8-OH-DPAT or m-CPP into the posterior third ventricle decreased TSH levels. The action of 5-HT was counteracted by metergoline, ketanserin and (+/-)-pindolol. Unexpectedly, m-CPP infusion into the anterior third ventricle also inhibited TSH secretion. The prolactin-elevating effects of 5-HT, 8-OH-DPAT and m-CPP were neither consistent nor site-specific. In conclusion, stimulation of both 5-HT1 and 5-HT2 receptors may inhibit TSH secretion, but the exact mechanism underlying the site-dependent action of 5-HT and 8-OH-DPAT on TSH secretion remains to be identified.
Interactions between a selective catechol-O-methyltransferase (COMT) inhibitor OR-462 and a monoamine oxidase (MAO)-A inhibitor clorgyline were studied measuring concentrations of L-dopa, dopamine and their metabolites in the rat hypothalamus and striatum after administration of levodopa/carbidopa (15/30 mg/kg i.p.). Part of the experiments were performed in rats pretreated with 6-OH-dopamine (6-OHDA) intracerebroventricularly (i.c.v.) to determine whether changes in dopamine metabolism occurred inside or outside catecholaminergic neurons. OR-462 was an effective COMT inhibitor at the doses 3 and 30 mg/kg i.p. Inhibition of 3-O-methyldopa (3-OMD) formation from L-dopa was reflected in the hypothalamus (45-81% decrease) and striatum (87-88% decrease), since 3-OMD penetrates the blood-brain barrier. Homovanillic acid (HVA) was decreased only in the striatum at 30 mg/kg of OR-462. Clorgyline (8 and 32 mg/kg i.p.) decreased 3,4-dihydroxyphenylacetic acid (DOPAC) formation in the hypothalamus and striatum by 61-91%. When given together, OR-462 and clorgyline elevated hypothalamic dopamine levels 3.2-4.6-fold, but striatal dopamine only 1.3-1.9-fold. The formation of 3-OMD and DOPAC remained suppressed and even brain HVA levels were decreased by 51-97%. 6-OHDA treatment decreased striatal and hypothalamic dopamine by 50% and noradrenaline by 75%. In these animals levodopa/carbidopa increased brain L-dopa 2.4-4-fold, those of 3-OMD 1.2-1.7-fold compared to intact animals, but the synthesis and metabolism of dopamine and the effects of COMT and MAO inhibitors were not significantly changed. Levodopa/carbidopa treatment decreased significantly prolactin and thyrotropin levels in serum but none of the additional treatments changed this action.
The effects of lesion of the hypothalamic paraventricular nuclei (PVNx), the main thyrotrophic area, on the cold-stimulated thyrotropin (TSH) responses to intracerebroventricular (i.c.v.) 5-HT were studied in male rats. PVNx significantly attentuated the cold-stimulated TSH levels, but significantly affected neither hypothalamic thyrotropin-releasing hormone nor somatostatin content. Serum T3 levels were significantly decreased 8 days after PVNx. Irrespective of the lesion (sham or PVNx), 5-HT infusion (9 micrograms per rat) into the posterior third ventricle attenuated markedly the cold-stimulated TSH levels, whereas infusion into the anterior third ventricle did not. Bilateral 5-HT infusions (2 micrograms per side) into the hypothalamic dorsomedial nuclei significantly decreased serum TSH, but bilateral infusions into the posterior hypothalamic nuclei were without effect. Sham-lesion and PVNx decreased serum prolactin levels without affecting the stimulation of prolactin secretion by i.c.v. 5-HT. These results suggest that the inhibitory effect of i.c.v. 5-HT on TSH secretion and its stimulatory action on prolactin secretion are only partially dependent on the PVN.