Functional connectivity of sensorimotor network is enhanced in spastic diplegic cerebral palsy: A multimodal study using fMRI and MEG

OBJECTIVE

To assess the effects to functional connectivity (FC) caused by lesions related to spastic diplegic cerebral palsy (CP) in children and adolescents using multiple imaging modalities.

METHODS

We used resting state magnetoencephalography (MEG) envelope signals in alpha, beta and gamma ranges and resting state functional magnetic resonance imaging (fMRI) signals to quantify FC between selected sensorimotor regions of interest (ROIs) in 11 adolescents with spastic diplegic cerebral palsy and 24 typically developing controls. Motor performance of the hands was quantified with gross motor, fine motor and kinesthesia tests.

RESULTS

In fMRI, participants with CP showed enhanced FC within posterior parietal regions; in MEG, they showed enhanced interhemispheric FC between sensorimotor regions and posterior parietal regions both in alpha and lower beta bands. There was a correlation between the kinesthesia score and fronto-parietal connectivity in the control population.

CONCLUSIONS

CP is associated with enhanced FC in sensorimotor network. This difference is not correlated with hand coordination performance. The effect of the lesion is likely not fully captured by temporal correlation of ROI signals.

SIGNIFICANCE

Brain lesions can show as increased temporal correlation of activity between remote brain areas. We suggest this effect is likely separate from typical physiological correlates of functional connectivity.

Altered excitation-inhibition balance in the primary sensorimotor cortex to proprioceptive hand stimulation in cerebral palsy

OBJECTIVE

Our objective was to clarify the primary sensorimotor (SM1) cortex excitatory and inhibitory alterations in hemiplegic (HP) and diplegic (DP) cerebral palsy (CP) by quantifying SM1 cortex beta power suppression and rebound with magnetoencephalography (MEG).

METHODS

MEG was recorded from 16 HP and 12 DP adolescents, and their 32 healthy controls during proprioceptive stimulation of the index fingers evoked by a movement actuator. The related beta power changes were computed with Temporal Spectral Evolution (TSE). Peak strengths of beta suppression and rebound were determined from representative channels over the SM1 cortex.

RESULTS

Beta suppression was stronger contralateral to the stimulus and rebound was weaker ipsilateral to the stimulation in DP compared to controls. Beta modulation strengths did not differ significantly between HP and the control group.

CONCLUSIONS

The emphasized beta suppression in DP suggests less efficient proprioceptive processing in the SM1 contralateral to the stimulation. Their weak rebound further indicates reduced intra- and/or interhemispheric cortical inhibition, which is a potential neuronal mechanism for their bilateral motor impairments.

SIGNIFICANCE

The excitation-inhibition balance of the SM1 cortex related to proprioception is impaired in diplegic CP. Therefore, the cortical and behavioral proprioceptive deficits should be better diagnosed and considered to better target individualized effective rehabilitation in CP.

Altered corpus callosum structure in adolescents with cerebral palsy: connection to gait and balance

Cerebral palsy (CP) is the most common motor disorder in childhood. Recent studies in children with CP have associated weakened sensorimotor performance with impairments in the major brain white-matter (WM) structure, corpus callosum (CC). However, the relationship between CC structure and lower extremity performance, specifically gait and balance, remains unknown. This study investigated the transcallosal WM structure and lower limb motor stability performance in adolescents aged 10-18 years with spastic hemiplegic (n = 18) or diplegic (n = 13) CP and in their age-matched controls (n = 34). The modern diffusion-weighted MRI analysis included the diffusivity properties of seven CC subparts and the transcallosal lower limb sensorimotor tract of the dominant hemisphere. Children with CP had comprehensive impairments in the cross-sectional area, fractional anisotropy, and mean diffusivity of the CC and sensorimotor tract. Additionally, the extent of WM alterations varied between hemiplegic and diplegic subgroups, which was seen especially in the fractional anisotropy values along the sensorimotor tract. The diffusion properties of transcallosal WM were further associated with static stability in all groups, and with dynamic stability in healthy controls. Our novel results clarify the mechanistic role of the corpus callosum in adolescents with and without CP offering valuable insight into the complex interplay between the brain's WM organization and motor performance. A better understanding of the brain basis of weakened stability performance could, in addition, improve the specificity of clinical diagnosis and targeted rehabilitation in CP.

Limb-specific thalamocortical tracts are impaired differently in hemiplegic and diplegic subtypes of cerebral palsy

Thalamocortical pathways are considered crucial in the sensorimotor functioning of children with cerebral palsy (CP). However, previous research has been limited by non-specific tractography seeding and the lack of comparison between different CP subtypes. We compared limb-specific thalamocortical tracts between children with hemiplegic (HP, N = 15) or diplegic (DP, N = 10) CP and typically developed peers (N = 19). The cortical seed-points for the upper and lower extremities were selected (i) manually based on anatomical landmarks or (ii) using functional magnetic resonance imaging (fMRI) activations following proprioceptive-limb stimulation. Correlations were investigated between tract structure (mean diffusivity, MD; fractional anisotropy, FA; apparent fiber density, AFD) and sensorimotor performance (hand skill and postural stability). Compared to controls, our results revealed increased MD in both upper and lower limb thalamocortical tracts in the non-dominant hemisphere in HP and bilaterally in DP subgroup. MD was strongly lateralized in participants with hemiplegia, while AFD seemed lateralized only in controls. fMRI-based tractography results were comparable. The correlation analysis indicated an association between the white matter structure and sensorimotor performance. These findings suggest distinct impairment of functionally relevant thalamocortical pathways in HP and DP subtypes. Thus, the organization of thalamocortical white matter tracts may offer valuable guidance for targeted, life-long rehabilitation in children with CP.

Proprioceptive response strength in the primary sensorimotor cortex is invariant to the range of finger movement

Proprioception is the sense of body position and movement that relies on afference from the proprioceptors in muscles and joints. Proprioceptive responses in the primary sensorimotor (SM1) cortex can be elicited by stimulating the proprioceptors using evoked (passive) limb movements. In magnetoencephalography (MEG), proprioceptive processing can be quantified by recording the movement evoked fields (MEFs) and movement-induced beta power modulations or by computing corticokinematic coherence (CKC) between the limb kinematics and cortical activity. We examined whether cortical proprioceptive processing quantified with MEF peak strength, relative beta suppression and rebound power and CKC strength is affected by the movement range of the finger. MEG activity was measured from 16 right-handed healthy volunteers while movements were applied to their right-index finger metacarpophalangeal joint with an actuator. Movements were either intermittent, every 3000 ± 250 ms, to estimate MEF or continuous, at 3 Hz, to estimate CKC. In both cases, 4 different ranges of motion of the stimuli were investigated: 15, 18, 22 and 26 mm for MEF and 6, 7, 9 and 13 mm for CKC. MEF amplitude, relative beta suppression and rebound as well as peak CKC strength at the movement frequency were compared between the movement ranges in the source space. Inter-individual variation was also compared between the MEF and CKC strengths. As expected, MEF and CKC responses peaked at the contralateral SM1 cortex. MEF peak, beta suppression and rebound and CKC strengths were similar across all movement ranges. Furthermore, CKC strength showed a lower degree of inter-individual variation compared with MEF strength. Our result of absent modulation by movement range in cortical responses to passive movements of the finger indicates that variability in movement range should not hinder comparability between different studies or participants. Furthermore, our data indicates that CKC is less prone to inter-individual variability than MEFs, and thus more advantageous in what pertains to statistical power.

More comprehensive proprioceptive stimulation of the hand amplifies its cortical processing

Corticokinematic coherence (CKC) quantifies the phase coupling between limb kinematics and cortical neurophysiological signals reflecting proprioceptive feedback to the primary sensorimotor (SM1) cortex. We studied whether the CKC strength or cortical source location differs between proprioceptive stimulation (i.e., actuator-evoked movements) of right-hand digits (index, middle, ring, and little). Twenty-one volunteers participated in magnetoencephalography measurements during which three conditions were tested: 1) simultaneous stimulation of all four fingers at the same frequency, 2) stimulation of each finger separately at the same frequency, and 3) simultaneous stimulation of the fingers at finger-specific frequencies. CKC was computed between MEG responses and accelerations of the fingers recorded with three-axis accelerometers. CKC was stronger (P < 0.003) for the simultaneous (0.52 ± 0.02) than separate (0.45 ± 0.02) stimulation at the same frequency. Furthermore, CKC was weaker (P < 0.03) for the simultaneous stimulation at the finger-specific frequencies (0.38 ± 0.02) than for the separate stimulation. CKC source locations of the fingers were concentrated in the hand region of the SM1 cortex and did not follow consistent finger-specific somatotopic order. Our results indicate that proprioceptive afference from the fingers is processed in partly overlapping cortical neuronal circuits, which was demonstrated by the modulation of the finger-specific CKC strengths due to proprioceptive afference arising from simultaneous stimulation of the other fingers of the same hand as well as overlapping cortical source locations. Finally, comprehensive simultaneous proprioceptive stimulation of the hand would optimize functional cortical mapping to pinpoint the hand region, e.g., prior brain surgery.

NEW & NOTEWORTHY Corticokinematic coherence (CKC) can be used to study cortical proprioceptive processing and localize proprioceptive hand representation. Our results indicate that proprioceptive stimulation delivered simultaneously at the same frequency to fingers (D2–D4) maximizes CKC strength allowing robust and fast localization of the human hand region in the sensorimotor cortex using MEG.

Identification of Proprioceptive Thalamocortical Tracts in Children: Comparison of fMRI, MEG, and Manual Seeding of Probabilistic Tractography

Studying white matter connections with tractography is a promising approach to understand the development of different brain processes, such as proprioception. An emerging method is to use functional brain imaging to select the cortical seed points for tractography, which is considered to improve the functional relevance and validity of the studied connections. However, it is unknown whether different functional seeding methods affect the spatial and microstructural properties of the given white matter connection. Here, we compared functional magnetic resonance imaging, magnetoencephalography, and manual seeding of thalamocortical proprioceptive tracts for finger and ankle joints separately. We showed that all three seeding approaches resulted in robust thalamocortical tracts, even though there were significant differences in localization of the respective proprioceptive seed areas in the sensorimotor cortex, and in the microstructural properties of the obtained tracts. Our study shows that the selected functional or manual seeding approach might cause systematic biases to the studied thalamocortical tracts. This result may indicate that the obtained tracts represent different portions and features of the somatosensory system. Our findings highlight the challenges of studying proprioception in the developing brain and illustrate the need for using multimodal imaging to obtain a comprehensive view of the studied brain process.

Corticokinematic coherence is stronger to regular than irregular proprioceptive stimulation of the hand

Proprioceptive afference can be investigated using corticokinematic coherence (CKC), which indicates coupling between limb kinematics and cortical activity. CKC has been quantified using proprioceptive stimulation (movement actuators) with fixed interstimulus interval (ISI). However, it is unclear how regularity of the stimulus sequence (jitter) affects CKC strength. Eighteen healthy volunteers (16 right-handed, 27.8 ± 5.0 yr, 7 females) participated in magnetoencephalography (MEG) session in which their right index finger was continuously moved at ∼3 Hz with Constant 333 ms ISI or with 20% Jitter (ISI 333 ± 66 ms) using a pneumatic-movement actuator. Three minutes of data per condition were collected. Finger kinematics were recorded with a three-axis accelerometer. CKC strength was defined as the peak coherence value in the Rolandic MEG gradiometer pair contralateral to the movement at 3 Hz. Both conditions resulted in significant coherence peaking in the gradiometers over the primary sensorimotor cortex. Constant stimulation yielded stronger CKC at 3 Hz (0.78 ± 0.11 vs. 0.66 ± 0.13, P < 0.001) and its first harmonic (0.60 ± 0.19 vs. 0.27 ± 0.11, P < 0.001) than irregular stimulation. Similarly, the respective sustained-movement evoked field was also stronger for constant stimulation. The results emphasize the importance of temporal stability of the proprioceptive stimulation sequence when quantifying CKC strength. The weaker CKC during irregular stimulation can be explained with temporal and thus spectral scattering of the paired peripheral and cortical events beyond the mean stimulation frequency. This impairs the signal-to-noise ratio of respective MEG signal and thus CKC strength. When accurately estimating and following changes in CKC strength, we suggest using precise movement actuators with constant stimulation sequence.NEW & NOTEWORTHY Cortical proprioceptive processing can be investigated using corticokinematic coherence (CKC). The findings show that CKC method is sensitive to temporal stability in the stimulation sequence. Although both regular and irregular sequences resulted in robust coherence, the regular stimulation sequence with pneumatic movement actuator is recommended to maximize coherence strength and reproducibility to allow better comparability between groups or populations.

Attention directed to proprioceptive stimulation alters its cortical processing in the primary sensorimotor cortex

Movement-evoked fields to passive movements and corticokinematic coherence between limb kinematics and magnetoencephalographic signals can both be used to quantify the degree of cortical processing of proprioceptive afference. We examined in 20 young healthy volunteers whether processing of proprioceptive afference in the primary sensorimotor cortex is modulated by attention directed to the proprioceptive stimulation of the right index finger using a pneumatic-movement actuator to evoke continuous 3-Hz movement for 12 min. The participant attended either to a visual (detected change of fixation cross colour) or movement (detected missing movements) events. The attentional task alternated every 3-min. Coherence was computed between index-finger acceleration and magnetoencephalographic signals, and sustained-movement-evoked fields were averaged with respect to the movement onsets every 333 ms. Attention to the proprioceptive stimulation supressed the sensorimotor beta power (by ~12%), enhanced movement-evoked field amplitude (by ~16%) and reduced corticokinematic coherence strength (by ~9%) with respect to the visual task. Coherence peaked at the primary sensorimotor cortex contralateral to the proprioceptive stimulation. Our results indicated that early processing of proprioceptive afference in the primary sensorimotor cortex is modulated by inter-modal directed attention in healthy individuals. Therefore, possible attentional effects on corticokinematic coherence and movement-evoked fields should be considered when using them to study cortical proprioception in conditions introducing attentional variation.

Gating Patterns to Proprioceptive Stimulation in Various Cortical Areas: An MEG Study in Children and Adults using Spatial ICA

Proprioceptive paired-stimulus paradigm was used for 30 children (10-17 years) and 21 adult (25-45 years) volunteers in magnetoencephalography (MEG). Their right index finger was moved twice with 500-ms interval every 4 ± 25 s (repeated 100 times) using a pneumatic-movement actuator. Spatial-independent component analysis (ICA) was applied to identify stimulus-related components from MEG cortical responses. Clustering was used to identify spatiotemporally consistent components across subjects. We found a consistent primary response in the primary somatosensory (SI) cortex with similar gating ratios of 0.72 and 0.69 for the children and adults, respectively. Secondary responses with similar transient gating behavior were centered bilaterally in proximity of the lateral sulcus. Delayed and prolonged responses with strong gating were found in the frontal and parietal cortices possibly corresponding to larger processing network of somatosensory afference. No significant correlation between age and gating ratio was found. We confirmed that cortical gating to proprioceptive stimuli is comparable to other somatosensory and auditory domains, and between children and adults. Gating occurred broadly beyond SI cortex. Spatial ICA revealed several consistent response patterns in various cortical regions which would have been challenging to detect with more commonly applied equivalent current dipole or distributed source estimates.

Optimization of Proprioceptive Stimulation Frequency and Movement Range for fMRI

For vision, audition and tactile sense, the optimal stimulus frequency for fMRI is somewhat known. For proprioception, i.e., the “movement sense”, however, the optimal frequency is unknown. We studied the effect of passive-finger-movement frequency on proprioceptive fMRI responses using a novel pneumatic-movement actuator. Eleven healthy right-handed volunteers participated in the study. The movement actuator passively moved the participant’s right index finger at frequencies of 0.3, 1, 3, 6, 9, or 12 Hz in a blocked design. A functional localizer was used to define regions-of-interest in SI and SII cortices. In addition, effect of movement range on the fMRI responses was tested in a separate session with 1, 3, 5, and 7 mm movement ranges at a fixed 2 Hz frequency. In primary somatosensory (SI) cortex, the responses were stronger at 3 Hz than at 0.3 Hz (p < 0.001) or 1 Hz (p < 0.05), and at ≥6 Hz than 0.3 Hz (p < 0.001 for frequencies ≥ 6 Hz). In secondary somatosensory (SII) cortex, all movements, except at 0.3 Hz, elicited significant responses of similar strength. In addition, 6, 9, and 12-Hz movements elicited a significant offset response in both SI and SII cortices (p < 0.001–0.05). SI cortex required a total stimulation duration of 4 min to elicit significant activations at the group-level whereas for SII cortex 1 min 20 s was sufficient. Increase in the movement range led to stronger responses in SI cortex, but not in SII cortex. Movements above 3 Hz elicited the strongest SI cortex responses, and increase in the movement range enhanced the response strength. We thus recommend that movements at 3–6 Hz with a movement range of 5 mm or higher to be used in future studies of proprioception. Our results are in-line with previous fMRI and PET studies using tactile or median nerve stimulation at different stimulation frequencies.

Serum Concentrations of 25-Hydroxyvitamin D and Depression in a General Middle-Aged to Elderly Population in Finland

OBJECTIVES

Low concentrations of serum 25-hydroxyvitamin D [25(OH)D] have been postulated to associate with an increased prevalence of depression. As there are a limited number of publications on this issue, we examined the association between serum 25(OH)D and depression in a general middle-aged or older population.

DESIGN

A population-based cross-sectional study.

SETTING AND PARTICIPANTS

A total of 1602 men and women from the population-based Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) in Eastern Finland, aged 53-73 y in 1998-2001, were analysed.

MEASUREMENTS

Depressive symptoms were assessed with the DSM-III depression scale, and those individuals who had scores over 4 (range 0-12) or had reported undergoing current antidepressant therapy, were considered as suffering from depression. Associations were estimated in serum 25(OH)D tertiles using logistic regression.

RESULTS

Among the participants, 183 subjects (11.4%) were considered to have depression. The mean age of the subjects was 62.6 years (SD 6.4, range 53.4-73.8 years). The mean serum 25(OH)D concentration was 43.8 nmol/L (SD 17.7, range 8.5-112.8 nmol/L), concentrations <50 nmol/L were observed in 65.0% of the subjects, and only 5.0% displayed concentrations ≥75 nmol/L. After multivariable adjustments, the odds ratios for having depression in the tertiles (from highest to the lowest) of serum 25(OH)D were 1, 1.35 (95 % CI: 0.87, 2.09) and 1.64 (95 % CI: 1.03, 2.59), P for trend=0.036.

CONCLUSION

These findings indicate that a lower concentration of serum 25(OH)D is associated with a higher prevalence of depression in an elderly general population.

LDL oxidative modification and carotid atherosclerosis: results of a multicenter study

OBJECTIVE

Serum LDL conjugated diene concentration is a marker of oxidative modification of LDL. We investigated the relationship between LDL conjugated dienes and cross-sectional subclinical atherosclerosis assessed by carotid IMT in high-risk subjects of a multicenter study.

METHODS

Serum LDL conjugated dienes and ultrasonographically assessed carotid intima-media thickness (IMT(mean), IMT(max) and IMT(mean-max)) were available for 553 subjects from Finland, France, Italy, the Netherlands, and Sweden.

RESULTS

In multivariate regression analysis, gender (p < 0.001), age (p < 0.001), systolic blood pressure (IMT(mean), p = 0.01; IMT(mean-max), p = 0.05) and serum LDL conjugated dienes (p = 0.02 for both IMT(mean) and IMT(mean-max)) were the strongest determinants of IMT variation, adjusted for study center, ultrasound videotape reader and serum LDL cholesterol. Pack-years of smoking, added into the regression model, did not destroy the significant association between increased serum LDL conjugated dienes and IMT. Ratio of LDL conjugated dienes to LDL particle cholesterol was higher in subjects of Northern recruiting centers than of Southern centers (r = 0.39, p < 0.0001).

CONCLUSIONS

There was a cross-sectional association between in vivo increased LDL oxidative modification and subclinical atherosclerosis after adjustment for traditional risk factors. The subjects in Northern countries of Europe had more oxidatively modified lipids per cholesterol in LDL particle than subjects in Southern countries.

Substituent effects on 13C chemical shifts of alkyl-substituted 4-oxo-1,3-dioxolanes and 5-oxo-1,3-oxathiolanes

The 13C NMR chemical shifts for 4-oxo-1,3-dioxolane (1) and its all methyl-substituted derivatives (2-10) as well as for 5-oxo-1,3-oxathiolane (11) and its nine alkyl-substituted derivatives (12-20) are reported. The magnitude and variety of the substituent effects are in accordance with the envelope conformations in which the oxygen or sulfur atom locates at the tip of the envelope as postulated on the basis of earlier data.

No effect on adenoma formation in Min mice after moderate amount of flaxseed

BACKGROUND & AIM

The mammalian lignan enterolactone (ENL) produced from plant lignans, e. g. secoisolariciresinol diglycoside (SDG), may protect against various cancers in humans. The present work aims to evaluate the effect of flaxseed on tumour formation in multiple intestinal neoplasia (Min) mice, a model for colon tumorigenesis.

DESIGN

Male and female Min mice were fed either with a non-fibre control diet or the same diet supplemented with 0.5 % (w/w) defatted flaxseed meal. Conversion of SDG to the mammalian lignans enterodiol (END) and ENL in the gut, and plasma ENL, were measured by HPLC with coulometric electrode array detector (CEAD) and timeresolved fluoroimmunoassay, respectively. Wild-type mice were also fed with the experimental diets in order to see whether lignan metabolism is different in Min and wild-type mice.

RESULTS

The total number of adenomas or their size in the small intestine was not different in the flaxseed and control groups. The flaxseed group had a tendency for a decreased number of colon adenomas in both genders. Gender and genotype based differences were found in the intestinal ENL levels. When compared to Min females, Min males in the flaxseed group had several fold higher ENL levels in the small intestine (Min males 125 +/- 124.5 nmol/g vs. females 22.8 +/- 16.0 nmol/g, P = 0.048) and caecum (47.6 +/- 31.6 nmol/g vs. females 14.5 +/- 6.6 nmol/g, P = 0.001). Presence of adenomas in the gut influences the intestinal lignan metabolism. Min mice had less intestinal END and ENL as compared with the wild-type mice (P < 0.05). Mean plasma ENL increased 7-fold during the flaxseed feeding (7 nmol/L in control vs. 50 nmol/L in flaxseed group) but no differences between gender and genotype were found. The plasma ENL level did not correlate with adenoma number in the small intestine and colon.

CONCLUSION

The number of intestinal adenomas in the Min mouse model is not related to ENL level in plasma nor is it associated with the levels of intestinal lignans. A gender difference in ENL lignan metabolism was found in the gut but not in the plasma.

Phloem fortification in rye bread elevates serum enterolactone level

OBJECTIVE

To analyse the lignan content of phloem powder enriched rye bread and to study the dose-response relationship of the effect of dietary plant lignans derived from phloem on intestinal production of enterolactone by measuring enterolactone concentration in serum.

DESIGN

A randomized double-blind supplementation trial.

SUBJECTS

Seventy-five non-smoking men recruited by newspaper advertisements.

INTERVENTION

Subjects were randomized to three study groups receiving either rye bread high in phloem (HP, 14% of rye flour substituted with phloem powder), rye bread low in phloem (LP, 7% of rye flour substituted with phloem powder) or placebo rye bread. Participants consumed 70 g of study bread daily for 4 weeks and provided serum samples for enterolactone analysis at baseline and at the end of the intervention.

RESULTS

There was a significant increase in serum enterolactone concentration in the LP and HP groups compared with the placebo group (P=0.009 and P=0.003, respectively). Considerable interindividual differences were observed in the response to dietary lignans within the study groups.

CONCLUSIONS

Our results indicate that plant lignans attached to insoluble fibre layer in phloem can be further metabolized and converted to enterolactone presumably by the bacteria present in the colon. Phloem powder is useful source of lignans for functional foods aimed to elevate serum enterolactone levels.

SPONSORSHIP

Phloem powder and the study breads were provided by Finnpettu Oy and Linkosuo Oy, respectively. The clinical study work was sponsored in part by Oy Jurilab Ltd.

Isoflavone content of the soy based supplements

A large number of soy isoflavone products with indications of possible health effects are available on the market. Fifteen different soy based products were analyzed using high performance liquid chromatography (HPLC) with coulometric electrode array detector to determine the total amount of isoflavones in aglycones after the hydrolysis and identify the different forms of the isoflavone conjugates. The aim of the study was to evaluate how well the isoflavone content data supplied by the producers correspond to our analysis results. Only one product contained isoflavones measured in aglycones the same amount as was the value given by the producer. The total amount of the isoflavones in aglycones ranged from 0.121 to 201 mg/g. Measured amounts of isoflavones in aglycones after the hydrolysis were in general lower than the values in the product labels. Product data were often confusing and the concrete amount of isoflavones was difficult to find out.

In vitro metabolism of plant lignans: new precursors of mammalian lignans enterolactone and enterodiol

The metabolism of the plant lignans matairesinol, secoisolariciresinol, pinoresinol, syringaresinol, arctigenin, 7-hydroxymatairesinol, isolariciresinol, and lariciresinol by human fecal microflora was investigated to study their properties as mammalian lignan precursors. The quantitative analyses of lignan precursors and the mammalian lignans enterolactone and enterodiol were performed by HPLC with coulometric electrode array detector. The metabolic products, including mammalian lignans, were characterized as trimethylsilyl derivatives by gas chromatography-mass spectrometry. Matairesinol, secoisolariciresinol, lariciresinol, and pinoresinol were converted to mammalian lignans only. Several metabolites were isolated and tentatively identified as for syringaresinol and arctigenin in addition to the mammalian lignans. Metabolites of 7-hydroxymatairesinol were characterized as enterolactone and 7-hydroxyenterolactone by comparison with authentic reference compounds. A metabolic scheme describing the conversion of the most abundant new mammalian lignan precursors, pinoresinol and lariciresinol, is presented.

Sensitive high-performance liquid chromatographic method for profiling phytoestrogens using coulometric electrode array detection: application to plasma analysis

An HPLC method for profiling 13 phytoestrogens and their metabolites using coulometric electrode array detection was developed. Sensitivity of the method was slightly less than that of our GC-MS method, but significantly higher compared to the HPLC methods using diode-array or UV detection. Detection limits varied from 3.4 (secoisolariciresinol) to 40.3 (genistin) pg on column. Signal linearities ranged from the detection limits to 61 ng on column. Resolution values for the peak pairs varied from 1.1 (O-desmethylangolensin-anhydrosecoisolariciresinol) to 16 (daidzin-genistin). Intra- and interassay retention time variations were negligible and detector response variation was eliminated by frequent calibration. Chromatographic method was applied to plasma analyses and 6 of the 13 compounds were detected. Method accuracy for those six analytes varied from 69% (enterodiol) to 118% (genistein). Intraassay precision CVs ranged from 1.5% (enterolactone, 12.4 nmol/liter) to 14% (genistein, 245 nmol/liter) and interassay precision CVs ranged from 9.9% (daidzein, 67.4 nmol/liter) to 44% (enterodiol, 1.20 nmol/liter).

HLA types in women with cervical human papillomavirus (HPV) lesions prospectively followed up for 10 years

Certain genotypes of HPV have been recently implicated in the etiology of carcinoma of the uterine cervix. In order to determine whether HLA antigen-controlled immunoregulatory functions have a role in the pathogenesis of HPV infections, class I and II HLA antigen typing was carried out on a series of 96 randomly selected women who were part of a cohort of 530 women prospectively followed up for cervical HPV infections in our clinic since 1981. The frequency of the DQ3 antigen, which has previously been reported to be increased among cervical cancer patients, was decreased in our HPV patients compared with the control group of Finnish women, but it was slightly increased in HPV16-infected women (P = 0.0812). However, we were able to demonstrate that HLA-DR5 antigen is significantly increased (i) in patients with high grade cervical intraepithelial neoplasia (CIN) (P < 0.02), and (ii) in women harbouring the high risk HPV type 16 (P = 0.0003), thus confirming earlier reports of an association of this HLA antigen and cervical cancer. Such a close association between the high risk HPV type 16 with an HLA antigen might have important implications in the possible immunogenetic basis of the increased risk for squamous cell carcinoma of the uterine cervix.

Infections and other illnesses of children in day-care centers in Helsinki. II: The economic losses

The economic consequences of illnesses among children in day-care centers (DCCs) were estimated in Helsinki during a one-year period, 1985-1986. The municipal DCCs took care of altogether 14,882 children at the end of 1985. In terms of money value in 1990, the total loss due to illnesses among all DCC children was $22,485,000 (1 US dollar = 3.80 FIM). Nearly half (46%) of this loss was caused by illnesses among children under three years of age, although these represent only 20% of the children in day care. The losses were $3,535 per child place in use among children under three years of age and $1,012 among older children. Economic losses due to the guardian's absence from work totalled $1,623, deficient utilization of DCCs $1,254, visits to a physician $169, hospitalization $221, paid care of children at home $219 and antibiotic courses $12 per child place in use for those under the age of three years. The corresponding figures for older children were 541, 248, 95, 51, 73 and 4 dollars per child. More than 90% of illnesses and costs were caused by infectious diseases. Because the costs due to illnesses among children under three years of age were more than three times as high as those for older children, preference should be given to home care and family day care for younger children and efforts should be made to find out how to build healthy DCCs for them.

Infections and other illnesses of children in day-care centers in Helsinki. I: Incidences and effects of home and day-care center variables

Illnesses among children attending municipal day-care centers (DCCs) were followed in a prospective study in Helsinki during 1985-1986. The study comprised 1,905 follow-up years among children in 29 DCCs. The mean number of illness periods was 4.9 per follow-up year, 7.9 for those under the age of three years and 3.8 for older children. The corresponding average numbers of days of illness were 23, 39 and 17. The most common diagnoses were upper respiratory tract infections (46.0%), diarrhea (17.2%), otitis media (12.9%), eye infections (4.0%), acute tonsillitis (3.2%), and bronchitis (3.0%). The six most common diagnoses, all infections, caused 86% of periods and 79% of days of illness. The ten most common infectious diseases caused 90.9% of absence periods, surgical operations 1.8%, and injuries 0.8%. In children under three years of age, a small area and volume of a DCC, lack of fully mechanized ventilation, and lack of separate facilities were associated with a higher incidence of one or all of the six most common infections. A large number of children at a DCC and small homes were associated with a high incidence of one or all of the most common infections among both younger and older children. The effects of passive smoking, number of siblings, number of household members, and incomes of families were not statistically significant.

T-lymphocyte subsets defined by double immunofluorescence in multiple sclerosis

T-lymphocyte subpopulations were studied in the blood of 25 multiple sclerosis patients and 25 healthy age and sex-matched controls. Monoclonal antibodies labelled with different fluorochromes were used to define the percentages of CD4 (helper/inducer) and CD8 (suppressor/cytotoxic) positive cells and to dissect them into phenotypic subgroups. The results confirm the decrease in CD8 positive cells in the blood associated with multiple sclerosis. The subset showing the most marked decrease was the CD11 marker negative population, which has been reported to be associated with cytotoxicity rather than suppression. There was no significant decrease in the percentage of cells positive for both CD4 and CD45R markers reported to contain suppressor-inducer or naive T-helper cells in the MS patients. The results suggest that further dissection of T-cell subpopulations may clarify our understanding of this disease process.

Lymphocyte subsets in the cerebrospinal fluid in active multiple sclerosis

We studied the relative number of lymphocyte subsets in the cerebrospinal fluid (CSF) of patients with active multiple sclerosis. The cells were double-labeled with monoclonal antibodies and were studied using a fluorescence-activated cell analyzer. The number of Leu2+Leu15+ cells and Leu3+Leu18+ cells was markedly reduced in the CSF but not in the peripheral blood of the patients. The number of Leu3+Leu18+ cells was reduced also in the CSF of control patients (patients with other inflammatory or infectious neurological diseases).

IgA, IgG and IgM anti-blood group A antibodies induced by pneumococcal vaccine

Pneumococcal polysaccharide vaccine contaminated with blood group A-like substance stimulated long-lasting production of anti-A antibodies in 10 of 11 subjects with O or B blood group. ELISA using blood group A substance as antigen detected increased IgA anti-A levels 18 months after vaccination in 82% of O and B subjects, the corresponding values being 73% for IgG and 18% for IgM. In females of O or B blood group becoming pregnant with a fetus of group A or AB, prior immunization to blood group A substance may cause a potential risk for haemolytic disease of the newborn.

Tumour-associated antigens in primary mouse fibroblasts induced by transformation with bovine papillomavirus type 1

Bovine papillomavirus type 1 (BPV 1) DNA was used to transform primary fibroblasts of C57BL/6J mice. Transformation frequency in these cells was much lower than in C127 cells and not associated with the appearance of morphologically distinct foci. However, continuous lines of transformed C57BL/6J cells were developed by serial subculturing of transfected cells. These transformed cell lines showed phenotypic properties associated with transformation including abnormal karyotypes. They contained variable amounts of viral DNA, but the copy number was in the same range as in six C127 transformants tested for comparison. In two cell lines monomeric viral DNA in an episomal form was detected. Slowly migrating viral sequences in these and in the third line were probably episomal concatamers, but the possibility of integration could not be excluded. There was some variation in immunogenicity, but all cell lines induced a cell-mediated immune response in syngeneic mice detected by the chromium release assay. In addition to BPV 1-transformed cell lines, the effector cells also reacted against an unidentified antigen shared by 2 cell lines transformed by SV40 and UV irradiation, respectively.

Cervical smears in assessment of the natural history of human papillomavirus infections in prospectively followed women

The value of cervical (Papanicolaou) smears in monitoring the natural history of cervical human papillomavirus (HPV) infections was assessed in a series of 513 women prospectively followed since 1981. On each clinic visit, the patients were subjected to colposcopy accompanied by cervical smears and/or punch biopsies. The latter were analyzed by light microscopy for concomitant cervical intraepithelial neoplasia (CIN) and by transmission electron microscopy (TEM) for HPV particles as well as for HPV structural proteins. The stromal immunocompetent cell (ICC) infiltrates were phenotypically characterized using monoclonal antibodies for T-cell subsets, NK and K cells and Langerhans cells. HPV DNA typing was accomplished by Southern blot, spot and in situ hybridization using probes for HPV 6, 11, 16, 18 and 31. Lesions showing only changes consistent with HPV infection (HPV-NCIN) were associated with less severe atypia in cervical smears than were lesions with coexistent CIN (HPV-CIN). Normal smears were observed, however, in 24.7% of the cases with HPV-NCIN lesions, in 11.5% of cases with HPV-CIN I lesions but only exceptionally in cases with HPV-CIN II and III lesions (2.2% and 3.3%). The percentages of the different ICC phenotypes did not correlate with the atypia in cervical smears, but there was a shift towards the lower values of the T-helper/T-suppressor (OKT4+/OKT8+) cell ratio in parallel with increasing atypia. The possibility of latent HPV infection was suggested by the detection of viral particles, HPV antigens and HPV DNA in lesions shedding normal cells in the smears. The high-risk HPV types 16 and 18 were associated with the highest frequency of severely atypical cells; in the majority of cases, the low-risk types HPV 6 and 11 presented with less severe atypia. The first cervical smear seems to be of value as a predictor of the natural history of HPV lesions, as indicated by the fact that regression was inversely and progression directly related to initial cellular atypia. The present results confirm the intimate association between HPV infections and CIN. Although the biologic potential of the HPV infections seems to be dependent on multiple factors, routine cervical smears, because of their potential value in monitoring the natural history of this infection, should constitute an important means in the prospective follow-up of these patients.

Characterization of in vivo activated lymphocytes found in the peripheral blood of patients undergoing cardiac operation

We studied in vivo lymphocyte activation in patients who underwent cardiac operation. A large number of deoxyribonucleic acid-synthesizing cells characterized by 3H-thymidine uptake and morphologically atypical lymphocytes were found after operation in the peripheral blood samples of patients, the peak level occurring on the sixth or seventh postoperative day. Most of the deoxyribonucleic acid-synthesizing cells were in the B cell fraction. The number of antibody secreting cells in the patients' peripheral blood samples was found increased from the normal level after operation. Immunoglobulin A-secreting cells were the most elevated fraction. The percentage of helper (OKT4) and suppressor (OKT8) cells in the postoperative samples was not significantly different from that in the preoperative samples. Only a few were Ia antigen positive cells. Co-culture of patients' B cells with their own T cells and with the T cells taken from two healthy controls revealed no signs of any helper or suppressor effect on these antibody-secreting cells. The results show that after cardiac operation the peripheral blood of patients contains an increased number of immunoglobulin secreting cells. The regulatory T-lymphocytes seem not to have any effect in vitro on these in vivo activated cells.

NK activity and NK-like non-specific cytolysis after PPD, rubella and measles antigen stimulation in multiple sclerosis

Blood samples were collected from 14 pairs of multiple sclerosis (MS) patients and from age- and sex-matched healthy controls. The cytotoxic activity of peripheral blood mononuclear cells was tested against the K562 cell line on the day of collection and again after 3 days in vitro culture with medium or with purified protein derivative of tuberculin (PPD), inactivated rubella virus or inactivated measles virus antigen. Lymphocytes from MS patients had a lower spontaneous cytotoxic activity compared to the controls both on the day of collection (P less than 0.025) and after 3 days in culture with medium alone (P less than 0.025). The activity decreased during in vitro culture in both groups, but the decrease was greater among MS patients (P less than 0.05). In cultures with antigens, a strong increase of NK-like cell-mediated cytolysis (NK-like CMC) was noted especially in cultures stimulated with PPD. There were no significant differences in the increase of the activity among MS patients and control subjects. A significant correlation between the increase of NK-like CMC and the lymphocyte blast transformation response induced by each antigen was found.

Post-mortem bacterial culture of bronchial mucus and heart blood in hospital and non-hospital autopsies: effect of morgue time and length of hospitalization

We studied cultures of 109 bronchial mucus and 67 heart blood specimens from unselected hospital autopsies and 40 bronchial mucus and heart blood specimens from unselected non-hospital (forensic) autopsies, performed 1-11 days after death. The most prevalent bacterium was Streptococcus viridans. No association was found between morgue time and the number of species isolated from each bronchial mucus or heart blood specimen in either hospital or non-hospital autopsies, nor between morgue time and the number of occasions different species were isolated from the bronchial mucus or heart blood specimens in either series. Bronchial mucus and heart blood cultures from the hospital autopsies gave more often gram negative rods and less often other microbes in result than those from the non-hospital autopsies (p less than 0.05 and p less than 0.025 respectively). There was a highly significant association between the length of hospitalization and the occurrence of gram negative rods both in the bronchial mucus and heart blood (p less than 0.001 and p less than 0.0001 respectively), a result which probably reflects the ante-mortem colonization of the respiratory tract with gram negative bacilli among hospitalized patients.

Postmortem radiographic, histological and bacteriological studies of terminal respiratory infections and other pulmonary lesions in hospital and non-hospital necropsies

One lung from 109 unselected hospital and 43 unselected non-hospital necropsies was studied using postmortem radiography with histological verification. Signs of acute bacterial infection, including bronchiolitis or bronchopneumonia, were present in 42.2% of the hospital necropsies and infection was the immediate cause of death in 8.3%. There was only one case of incipient bronchopneumonia among the non-hospital necropsies. Emphysema was the most common other pulmonary lesion in both groups. Gram negative bacteria were found significantly more often in the bronchial mucus of lungs with any pulmonary lesion, particularly those with signs of bacterial infection, than in the bronchial mucus of morphologically normal lungs in both groups of patients. In addition, the frequency of infections was associated with length of stay in hospital. This may reflect the prevalence of Gram negative infections in hospitals.

Cell-mediated immunodeficiency in Down's syndrome: normal IL-2 production but inverted ratio of T cell subsets

To get more information on the mechanism of cell-mediated immunodeficiency associated with Down's syndrome, 18 patients were studied for PHA-induced lymphocyte transformation and interleukin-2 (IL-2) production. A normal amount of IL-2 was produced although half of the patients showed decreased blast transformation. T cell subpopulations were studied in some patients with decreased and with normal blast transformation. All studied patients with decreased blast transformation had inverted helper/suppressor T cell ratio.

Enzyme-linked immunosorbent assay (ELISA) with bacterial sonicate antigen for IgM, IgA, and IgG antibodies to Francisella tularensis: comparison with bacterial agglutination test and ELISA with lipopolysaccharide antigen

An enzyme-linked immunosorbent assay (ELISA) with bacterial sonicate (S) as antigen developed for determining the presence of IgM, IgA, and IgG antibodies to Francisella tularensis was compared with the bacterial agglutination (BA) test and a corresponding ELISA using lipopolysaccharide (LPS) antigen. Of the organisms tested, F tularensis was the only one to cause significant inhibition, indicating the specificity of the S-ELISA. BA test titers correlated significantly with antibody levels in all three immunoglobulin classes and most closely with IgM antibodies (r = 0.83). With some minor exceptions, the S-ELISA and the LPS-ELISA gave identical results, and the correlations between the tests were very close (r = 0.94-0.99). The S-ELISA confirmed the tularemia diagnosis with the first serum specimens from 43% of patients with tularemia vs 17% of the BA test. In addition, no seroconversion was observed by the BA test in 4% of the patients, although large increases were observed in S-ELISA titers.

Defective B cell function associated with inherited interstitial deletion of the short arm of the X chromosome

The B cell function of a patient with low serum immunoglobulin (Ig) levels and with an interstitial deletion in the short arm of one of her X chromosomes (del(Xp] and the B cell function of her relatives were analyzed by indirect protein A plaque-forming cell (PFC) assay and by measuring immunoglobulin secretion in vitro by ELISA. B cells were activated by pokeweed mitogen (PWM) with or without hydrocortisone (HC) to inhibit HC-sensitive suppressor cells. The patient, her mother, and one sister, all of them having del(Xp), generated very few PFC induced by PWM, even in the presence of HC, whereas normal PFC responses were found in the patient's cytogenetically normal sisters. The B cells of the subjects with del(Xp) secreted very low amounts, if any, of IgA, IgG, and IgM. Co-culture experiments with B cells from del(Xp) subjects and normal OKT 4+ cells revealed no or very low Ig production. The function of the del(Xp) subjects' OKT 4+ cells was slightly reduced, whereas the activity of their OKT 8+ cells was normal. The cell subset analysis in the peripheral blood revealed decreased OKT 4+:8+ ratios in all del(Xp) subjects. The results indicate an intrinsic B cell defect with a possible concomitant immunoregulatory defect associated with del(Xp). Moreover, the results support the hypothesis that antibody production is at least partially controlled by genes located in the short arm of the X chromosome.

Defective B cell function associated with inherited interstitial deletion of the short arm of the X chromosome

The B cell function of a patient with low serum immunoglobulin (Ig) levels and with an interstitial deletion in the short arm of one of her X chromosomes (del(Xp] and the B cell function of her relatives were analyzed by indirect protein A plaque-forming cell (PFC) assay and by measuring immunoglobulin secretion in vitro by ELISA. B cells were activated by pokeweed mitogen (PWM) with or without hydrocortisone (HC) to inhibit HC-sensitive suppressor cells. The patient, her mother, and one sister, all of them having del(Xp), generated very few PFC induced by PWM, even in the presence of HC, whereas normal PFC responses were found in the patient's cytogenetically normal sisters. The B cells of the subjects with del(Xp) secreted very low amounts, if any, of IgA, IgG, and IgM. Co-culture experiments with B cells from del(Xp) subjects and normal OKT 4+ cells revealed no or very low Ig production. The function of the del(Xp) subjects' OKT 4+ cells was slightly reduced, whereas the activity of their OKT 8+ cells was normal. The cell subset analysis in the peripheral blood revealed decreased OKT 4+:8+ ratios in all del(Xp) subjects. The results indicate an intrinsic B cell defect with a possible concomitant immunoregulatory defect associated with del(Xp). Moreover, the results support the hypothesis that antibody production is at least partially controlled by genes located in the short arm of the X chromosome.

Serum iron, copper, zinc, ferritin, and ceruloplasmin after intense heat exposure

Twelve voluntary adult subjects twice took a 30-min sauna bath, at a temperature of 80 degrees C with a 30-min rest between each, every 12 h for 1 week. Measurements of serum iron, copper, zinc, ferritin and ceruloplasmin were performed before the experiment, after the first and second 30 min in the sauna and at the end of the week. The first two sauna baths did not significantly change the concentrations of the trace elements measured. After the week the mean serum copper concentration had decreased from 15.0 (SD 1.7) mumol x 1-1 to 13.5 (SD 2.0) mumol x 1-1 (p less than 0.02). The mean zinc concentration decreased from 13.8 (SD 2.4) mumol x 1-1 to 9.8 (SD 1.8) mumol x 1-1 (p less than 0.001) during the week of the experiment. At the beginning of the study period two subjects had zinc concentrations below the reference values and after the week nine subjects had zinc concentrations below the reference values. The concentration of serum ferritin decreased from 142.2 (SD 103) micrograms x 1-1 to 111.3 (SD 89) micrograms x 1-1 (p less than 0.02) whereas the values of ceruloplasmin remained unchanged. Our findings confirm the earlier suggestion that heavy exposure to heat can cause a loss of some trace elements, especially zinc.

Plasmid associated antibody production against Yersinia enterocolitica in man

The presence of plasmids was studied in 46 Yersinia enterocolitica strains isolated from human fecal specimens. In the 36 cases where specific antibodies were detected, 33 of the isolated bacteria were harbouring a 45-48 Mdalton plasmid responsible for autoagglutination and Ca2+ dependent growth at 37 degrees C. Symptoms compatible with yersiniosis were present in all patients where information was available. In the 10 cases with clinical symptoms but without specific antibodies only 2 of the isolated yersinia strains contained plasmids which were of another size. These results indicate an association between the presence of the 45-48 Mdalton plasmid in Y. enterocolitica strains and the pathogenicity of the strains to human hosts.

Rapid detection of rotavirus in stool by latex agglutination: comparison with radioimmunoassay and electron microscopy and clinical evaluation of the test

A latex agglutination test (LX) using antisera prepared against Nebraska calf diarrhea virus (NCDV) is described for the detection of rotavirus in stool of children with acute gastroenteritis. The test was compared with electron microscopy (EM) and radioimmunoassay (RIA) with 100 stools positive or negative for rotavirus. Out of 53 stools positive in RIA or EM, 49 were positive in LX and 4 were negative. Two specimens negative in EM and RIA were falsely positive in LX. The method was also tested in two clinical series with 115 stools from 101 children. Altogether 67/115 stools were positive in RIA, and 62/115 in LX. Out of 7 stools with contradictory results, 6 were negative in LX but positive in RIA, and 1 was positive in LX but negative in RIA. The results indicate that the LX is suitable for rapid screening of rotavirus gastroenteritis in clinical practice.

Acute phase proteins, humoral and cell mediated immunity in environmentally-induced hyperthermia in man

The effects of repeated hyperthermia, caused by a Finnish sauna bath over 1 week, on the serum levels of some acute phase reactant proteins and on both humoral and cell-mediated immunity on twelve healthy young volunteers are presented. The mean rise in rectal temperature during each 30-min period in the bath was about 1.3 degrees C. Heat exposure caused significant increases in the serum concentrations of two of the acute phase reactant proteins, alpha1-antitrypsin (from a mean value of 1.8 (0.1) to 1.9 (0.2) g X l-1, p less than 0.01) and transferrin (from a mean value of 36.9 (3.4) to 38.3 (4.4) mumol X l-1, p less than 0.05), but no changes occurred in immunoglobulins or cell-mediated immunity. These findings suggest that environmentally induced hyperthermia can initiate the acute phase reaction associated with fever.

The association of serum IgM and IgG levels with the number of X chromosomes in patients with abnormal number of X chromosomes

The following attributes of the immune response were studied from nine patients with different numbers of X chromosomes: serum immunoglobulin levels, C3 and C4 concentrations, the presence of autoantibodies, phagocytosis, killing of bacteria, the chemotactic response of neutrophils, the in vitro response of lymphocytes to PHA, ConA, PwM, PPD and oidiomycin; and the proportion of T lymphocytes was determined. The number of X chromosomes varied from one (45,X) to four (48,XXXX). No evidence of severe dysfunction in the immune system was found in any of the patients. The correlation coefficients between the serum concentration of IgM and IgG and the number of X chromosomes present were statistically significant (r = 0.691, P less than 0.05, and r = 0.714, P less than 0.05, respectively). The serum IgA concentration showed a tendency towards a negative correlation. The concentrations of neither IgD nor IgE correlated to the number of X chromosomes. It seems obvious that the number of X chromosomes is positively associated with the concentration of serum IgG and IgM. The results support the hypothesis that antibody production is at least partially controlled by genes located in the X chromosome.

Antibody response to pneumococcal vaccine in patients with trisomy-21 (Down's syndrome)

The antibody response to pneumococcal vaccine was lower in adults with trisomy-21 (Down's syndrome) than in controls. Males gave lower response than females, significantly so among the 21-trisomic patients. The antibody response to different polysaccharides differed between the groups.

Immune function in patients with chromosome deletions

Non-specific, cell-mediated and humoral immunity were evaluated in six patients with different autosomal deletions, and in two patients with X-chromosome deletions. Six had an increased number of bacterial, viral, and mycotic infections. Mild disturbances were found in the immunological functions of almost every patient. Granulocyte phagocytosis and killing of bacteria were normal in all patients. The chemotactic response was increased in two, and normal in the others. The responses to phytohaemagglutinin and pokeweed mitogen were normal in all patients and the response to concanavalin A was decreased in one patient. The lymphocyte response to purified protein derivative was decreased in the patients as a group when compared to the controls (P less than 0 . 005), but normal to oidiomycin. The number of acid-alpha-naphthyl acetate esterase positive cells was low in four patients. One had a high titre of antinuclear and antithyroid antibodies. One had a low concentration of serum IgA, C3 and C4. One had a high concentration of IgM. Two had elevated levels of C3 and C4. Our results show that several different chromosomal deletions are associated with immunological abnormality.

Natural killer cell function in trisomy-21 (Down's syndrome)

Natural killer (NK) activity and antibody-dependent cell mediated cytotoxicity (ADCC) against a human myeloid target cell line (K 562) was measured in adult patients with trisomy-21 (Down's syndrome) and in chromosomally normal age and sex matched control subjects. The effect of human leucocyte interferon (IFN-alpha) on the NK activity was also estimated. Spontaneous NK activity was stronger in the adult patients with trisomy-21 than in the healthy controls, but the difference did not reach statistical significance. The augmentation of NK activity by IFN-alpha, measured using lymphocytes not depleted of monocytes as effector cells, was statistically significant in both the trisomic patients (P less than 0.004) and the healthy controls (P less than 0.0005). Using monocyte and macrophage depleted lymphocytes in the patients with trisomy-21 the NK activity proved stronger than in the healthy controls, but not significantly and IFN-alpha did not augment it as it did in the healthy controls (P = n.s., P less than 0.05), for augmentations respectively). These results support the view that monocytes and macrophages are connected with the NK cell system. ADCC correlated with NK activity in both groups. Since NK cells are important components of many immune processes, including tumour and virus and/or bacteria-infected cell elimination, and have regulatory functions in immune reactions, the deficient augmentation of trisomic NK cells shown in vitro with extrinsic human leucocyte interferon may, paradoxically be an explanation for the greater susceptibility of trisomic individuals to lymphatic leukaemia and virus and bacterial infections. In vivo, this could be explained by the more potent secondary suppression by the 'immune' interferon produced by the virus, bacteria and malignant cells. In other words, the potential of the 'fighting couple' of the immune system, NK cell/interferon, is perhaps disturbed genetically due to the chromosome 21.