A genome-wide search for alleles and haplotypes associated with autism and related pervasive developmental disorders on the Faroe Islands

The involvement of genetic factors in the etiology of autism has been clearly established. We undertook a genome-wide search for regions containing susceptibility genes for autism in 12 subjects with childhood autism and related pervasive developmental disorders (PDDs) and 44 controls from the relatively isolated population of the Faroe Islands. In total, 601 microsatellite markers distributed throughout the human genome with an average distance of 5.80 cM were genotyped, including 502 markers in the initial scan. The Faroese population structure and genetic relatedness of cases and controls were also evaluated. Based on a combined approach, including an assumption-free test as implemented in CLUMP, Fisher's exact test for specific alleles and haplotypes, and IBD(0) probability calculations, we found association between autism and microsatellite markers in regions on 2q, 3p, 6q, 15q, 16p, and 18q. The most significant finding was on 3p25.3 (P(T1)=0.00003 and P(T4)=0.00007), which was also supported by other genetic studies. Furthermore, no evidence of population substructure was found, and a higher degree of relatedness among cases could not be detected, decreasing the risk of inflated P-values. Our data suggest that markers in these regions are in linkage disequilibrium with genes involved in the etiology of autism, and we hypothesize susceptibility genes for autism and related PDDs to be localized within these regions.

Possible evidence for a common risk locus for bipolar affective disorder and schizophrenia on chromosome 4p16 in patients from the Faroe Islands

Patients with schizophrenia (n=11) and bipolar affective disorder (n=17) from the relatively isolated population of the Faroe Islands were genotyped for 34 polymorphic markers on chromosome 4 in a search for allelic association and haplotype sharing among distantly related patients. When considering bipolar patients only, there was no clearcut support for any region on chromosome 4. The two-marker segment D4S394-D4S2983 at 4p16.1 was, however, supported by a P-value of 0.0162. For patients with schizophrenia, there was reasonable support for 4p16.1 as marker D4S2281 (P=0.0019), a two-marker segment (D4S2281-D4S1605, P=0.0009) and a three-marker segment (D4S2923-D4S2928-D4S1582, P-0.0005) appeared to be associated with schizophrenia, with some alleles/haplotypes occurring with different frequencies in patients compared to controls. When combining both psychiatric disorders, chromosome 4p16.1 received further support from five partially overlapping two- and three-marker segments (D4S394-D4S2983, P=0.0039; D4S2281-D4S1605, P=0.0027 and D4S394-D4S2983-D4S2923, P=0.006; D4S2923-D4S2928-D4S1582, P=0.00007; D4S1582-D4S1599-D4S2281, P=0.005). Increased haplotype sharing in patients with schizophrenia and in the combined data set was partly supported by Fisher's exact test and tests based on the genealogy. Our study yields support for a common risk gene for schizophrenia and bipolar affective disorder on the short arm of chromosome 4, as suggested by previous findings in the neighbouring Scottish population.

Search for common haplotypes on chromosome 22q in patients with schizophrenia or bipolar disorder from the Faroe Islands

Chromosome 22q may harbor risk genes for schizophrenia and bipolar affective disorder. This is evidenced through genetic mapping studies, investigations of cytogenetic abnormalities, and direct examination of candidate genes. Patients with schizophrenia and bipolar affective disorder from the Faroe Islands were typed for 35 evenly distributed polymorphic markers on 22q in a search for shared risk genes in the two disorders. No single marker was strongly associated with either disease, but five two-marker segments that cluster within two regions on the chromosome have haplotypes occurring with different frequencies in patients compared to controls. Two segments were of most interest when the results of the association tests were combined with the probabilities of identity by descent of single haplotypes. For bipolar patients, the strongest evidence for a candidate region harboring a risk gene was found at a segment of at least 1.1 cM including markers D22S1161 and D22S922 (P=0.0081 in the test for association). Our results also support the a priori evidence of a susceptibility gene to schizophrenia at a segment of at least 0.45 cM including markers D22S279 and D22S276 (P=0.0075). Patients were tested for the presence of a missense mutation in the WKL1 gene encoding a putative cation channel close to segment D22S1161--D22S922, which has been associated with schizophrenia. We did not find this mutation in schizophrenic or bipolar patients or the controls from the Faroe Islands.

Effect of overexpressing GLUT-1 and GLUT-4 on insulin- and contraction-stimulated glucose transport in muscle

To examine the effects of GLUT-1 on GLUT-4-dependent, insulin-stimulated, and contraction-stimulated 2-deoxy-D-glucose (2-DG) transport, we overexpressed GLUT-1 in metabolically heterogeneous skeletal muscles [red and white tibialis anterior (TA) and extensor digitorum longus (EDL)] via 7 days of chronic electrical stimulation. GLUT-1 was increased 1.6- to 16.4-fold (P < 0.05). Basal 2-DG transport was increased 1.7- to 3.0-fold (P < 0.05) and was equal to (red TA and EDL; P > 0.05) or exceeded insulin-stimulated 2-DG transport by 50% (white TA; P < 0.05) in the control muscles. GLUT-4 was concomitantly overexpressed (2.1- to 4.4-fold; P < 0.05). Insulin-stimulated 2-DG transport was increased 1.6- to 2.5-fold (P < 0.05). During muscle contractions, 2-DG transport increased 9- to 12-fold (P < 0.05) in control muscles, but this was reduced by approximately 25% (P < 0.05) in muscles overexpressing GLUT-1 and GLUT-4 (red TA and EDL). In contrast, in the experiment, white TA contraction-stimulated 2-DG transport was increased 1.7-fold (P < 0.05). Therefore, overexpression of GLUT-1, when GLUT-4 is also overexpressed, does not impair insulin-stimulated 2-DG transport, although contraction-stimulated transport may be reduced in some muscles.

Effect of electrical stimulation patterns on glucose transport in rat muscles

Transport of 2-[3H]deoxy-D-glucose (2-DG) was investigated during supramaximal stimulations of different muscles. In addition, we varied the net stimulation time (NST). In different treatments, NST occupied either 5, 7.5, 10, 15, 20, 30, or 50% of a 20-min stimulation period. After a bolus injection of 3H-labeled 2-DG, the greatest transport occurred in the extensor digitorum longus. In red gastrocnemius (RG; type IIa fibers) and white gastrocnemius (WG; type IIb fibers), the 2-DG transport rate was highest at 10% NST (8- to 12-fold increase) and decreased thereafter. In soleus (type I fibers), the 2-DG transport increased from 5 to 50% NST. Below 30% NST, 2-DG transport was greater in RG and WG muscles than in soleus (P < 0.05). GLUT-4 and 2-DG transport were not correlated during the contractions. Therefore, the percent NST affects 2-DG transport differentially in muscles of varying fiber types, and the transport rate is not related to the GLUT-4 content of the muscles.

Soccer injuries in Iceland

We investigated the frequency, cause and location of injuries in Icelandic elite soccer in 1991. The incidence of injuries for the individual player was 34.8 +/- 5.7 per 1000 game-hours and 5.9 +/- 1.1 per 1000 practice-hours. The most common types of injuries were muscle strains (29%), ligament sprains (22%), contusions (20%), and other injuries (29%). The frequency of reinjury was markedly high, where 44% of the strains and 58% of the sprains were registered as reinjuries. Strains occurred mainly during sprinting, sprains by tackling, and contusion during other contact. Significantly more injuries occurred on artificial turf than on grass or gravel in correlation to number of hours in games and practices. Teams who had the longest pre-season preparation period obtained significantly fewer injuries during the season.

Different beta-adrenergic receptor density in different rat skeletal muscle fibre types

The effects of adrenaline on skeletal muscle differ between fibre types. The aim of the present study was to investigate the beta-adrenoceptor density, affinity and subtype in rat skeletal muscles with different fibre type composition. beta-Adrenoceptors were determined in cryostat sections to avoid methodological problems with variable recovery, using the non-selective beta-adrenoceptor ligand [3H]CGP-12177 and beta 1- and beta 2-selective cold ligands CGP 20712A and ICI 118,551. In the presence of protease inhibitors [3H]CGP-12177 binding was stable, saturable, reversible, and displaceable. Scatchard analysis of binding saturation data was compatible with a single class of specific binding sites. Binding site density (Bmax) was higher (P < 0.02) in adult soleus (9.38 +/- 1.13 fmol x mg protein-1) than in adult extensor digitorum longus (4.74 +/- 0.39 fmol x mg protein-1), whereas the dissociation constants (Kd), 0.37 +/- 0.05 and 0.31 +/- 0.04 nM for soleus and extensor digitorum longus, respectively, were not significantly different. For young rats (5-6 weeks), Bmax was 11.21 +/- 0.33 and 5.45 +/- 0.11 fmol x mg protein-1 (P < 0.05), and Kd was 0.27 +/- 0.02 and 0.24 +/- 0.04 nM for soleus and epitrochlearis, respectively. These results correspond to a receptor density of 2 and 1 pmol x g w.wt.-1 in muscles containing.mainly type I and type II fibres, respectively. Displacement studies with CGP 20712A and ICI 118,551 were compatible with mainly beta 2-adrenoceptors, but 7-10% beta 1-adrenoceptors were present in both types of muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenaline stimulated glycogen breakdown in rat epitrochlearis muscles: fibre type specificity and relation to phosphorylase transformation

The effect of adrenaline on glycogen breakdown in different skeletal muscle fibre types was investigated in the epitrochlearis muscle in vitro. Histochemical studies showed that adrenaline stimulated glycogen breakdown in all three major fibre types, with a higher absolute glycogen breakdown in type IIB fibres compared to type IIA and type I fibres. In biochemical studies we found that the glycogenolytic rate decreased during prolonged incubation with adrenaline, although the percentage phosphorylase in the a form and the concentration of glucose-6-phosphate (G-6-P) remained high. In the dose response studies we found an EC50 of 2.2 x 10(-8) M adrenaline for adrenaline stimulated glycogen breakdown, with an EC50 of 2.0 x 10(-7) M for adrenaline stimulated accumulation of G-6-P, excluding G-6-P as the key inhibitor of phosphorylase a activity.

Different effects of physical training on the morphology of motor nerve terminals in the rat extensor digitorum longus and soleus muscles

The morphology of nerve terminals in the rat extensor digitorum longus and soleus muscles was studied with light microscopy in 13-week-old male animals after 6 weeks of treadmill running and compared with data from untrained controls. The terminals were stained with methylene blue. Physical training tended to increase the area and length of the nerve terminals in relation to the corresponding muscle fiber diameter, and to reduce the density of nerve terminal varicosities, but significant differences between the trained group and the control group were obtained only in the extensor digitorum longus muscle. The different degrees of effect on the nerve terminals in the two muscles may be due to different abilities to respond to the training, but may also be due to differences in work load caused by the training. The effect of training on extensor digitorum longus junctions may reflect some transformation from fast to slow morphological characteristics.

How unequivocal is the muscle fibre type concept?

Different histochemical identification methods for muscle fibre types have been introduced over the years. Most of them have been based on myosin ATPase activity after different kinds of preincubations, alone or in combination with oxidative enzymes. Comparative studies have shown, however, that the different methods result in nonidentical subgroups of type II fibres. Optical density values of individual fibres after incubation of serial sections for alkali- or copper-preincubated ATPase, NADH-TR, and fibre diameter, combined in two-dimensional plots, have for a long time been used in our laboratory to separate three subgroups of type II fibres. A cluster analysis, based on the data mentioned above, results in three subgroups of type II fibres in rat plantaris muscle. In comparison, earlier studies comparing different histochemical methods and reporting lack of correspondence between them have been based on two subgroups of type II fibres only. It is suggested that part of the lack of correspondence is due to unequal and incomplete separation by the methods used in the comparative studies, and that the three subgroups of type II fibres identified in the cluster analysis are type IIA, IIX and IIB, respectively. The need for a consensus on a common basis for histochemical identification of muscle fibre types is emphasized.

Comparison of changes in testosterone concentrations after strength and endurance exercise in well trained men

Changes in the testosterone concentrations after single sessions of endurance and strength training were measured in seven well trained men, experienced in both forms of training. Both training sessions were rated as hard to very hard on the Borg scale. Blood samples for testosterone measurements were taken before, immediately after, and 2, 4 and 6 h after the training sessions as well as the next morning. The mean testosterone concentration increased 27% (P less than 0.02) and 37% (P less than 0.02) during the strength and endurance training session, respectively. Two hours after the training sessions the mean testosterone concentration had returned to the pre-training level and remained at that level for the length of the observation period. There were no significant differences in the changes in testosterone concentration after strength and endurance training but there were large differences in the testosterone response at the level of the individual. A high correlation (r = 0.98; P less than 0.001) for individuals was found between increases in testosterone concentration after strength and after endurance training. It was concluded that the changes in mean testosterone values followed the same timecourse after single sessions of strength and endurance training of the same duration and perceived exertion. The interindividual differences in testosterone response may be of importance for individual adaptation to training.

Adrenaline-mediated glycogenolysis in different skeletal muscle fibre types in the anaesthetized rat

The effect of adrenaline infusion on glycogen breakdown in different muscle fibres types in resting extensor digitorum longus (EDL) and soleus was investigated with histochemical methods. During adrenaline infusion the glycogen content in type IIB and type IIA fibres in EDL, as measured in PAS-stained sections, decreased 24.5% and 11.5% respectively. The glycogen content in type I fibres in EDL and in type I, type IIA and T-fibres in soleus did not change during adrenaline infusion. The present study shows that adrenaline infusion has different effects on glycogen breakdown in the different fibre types in EDL and a different effect on type IIA fibres in EDL and soleus. So far, the reason for these differences is unknown.

Oxidative capacity of tissues contributing to thermogenesis in eider (Somateria mollissima) ducklings: changes associated with hatching

1. The development of liver and skeletal muscle oxidative capacities during hatching of the common eider (Somateria mollissima) in the Arctic has been investigated by monitoring tissue cytochrome c oxidase activity. 2. The specific activity of the liver enzyme did not change as the embryo underwent hatching, nor during subsequent growth of the duckling into adulthood. 3. Thigh muscle enzyme specific activity increased by a factor of 3.4 during the 24 h prehatching period, remained elevated for at least 48 h after hatching, and then returned to the embryonic (-24 h) level in adults. 4. Histochemically visualized NADH-tetrazolium reductase of a typical red thigh muscle, M. vastus lateralis, showed a distinct increase in activity as the hatching process progressed to completion. 5. Electron microscopy of sectioned M. vastus lateralis revealed a dramatic increase in the density of the myofibrillar structure (number of mitochondrial profiles per unit area), and in the surface area of mitochondrial crista membranes in the course of the 48 h interval from 1 day prehatching to 1 day after hatching. 6. The significance of these changes for the scaling of thermoregulatory heat generation in the newly hatched eider duckling is discussed.

Experimental laryngeal reinnervation by phrenic nerve implantation into the posterior cricoarytenoid muscle

Under general anaesthesia, 5 dogs underwent sectioning of the right recurrent nerve followed by implantation of the phrenic nerve into the posterior cricoarytenoid (PCA) muscle. Some 6-7 months later the dogs were sacrificed after registration of vocal cord motility. Still photographs and movie film of the larynx were taken during quiet and forced respiration and at electrical stimulation of the implanted phrenic nerve. The PCA and vocal muscles were removed for histochemical studies. We found practically no abductory movement of the vocal cord on the reinnervated side, either during quiet or forced respiration. During forced inspiration there was, however, a slight medial bowing of the right vocal cord. At electrical stimulation there was a sphincteric movement of the entire larynx. Histochemistry showed a reinnervation picture of both the PCA and the vocal muscles on the experimental side. The conclusion drawn from this study is that axonal escape, probably from the implantation site, results in an unwanted reinnervation of laryngeal adductor muscles, which neutralize the abducting effect of the PCA muscle during inspiration. This method therefore does not seem to be suitable as a treatment alternative for bilateral recurrent nerve paralysis.

Experimental laryngeal reinnervation by phrenic nerve implantation into the posterior cricoarytenoid muscle

Under general anaesthesia, 5 dogs underwent sectioning of the right recurrent nerve followed by implantation of the phrenic nerve into the posterior cricoarytenoid (PCA) muscle. Some 6-7 months later the dogs were sacrificed after registration of vocal cord motility. Still photographs and movie film of the larynx were taken during quiet and forced respiration and at electrical stimulation of the implanted phrenic nerve. The PCA and vocal muscles were removed for histochemical studies. We found practically no abductory movement of the vocal cord on the reinnervated side, either during quiet or forced respiration. During forced inspiration there was, however, a slight medial bowing of the right vocal cord. At electrical stimulation there was a sphincteric movement of the entire larynx. Histochemistry showed a reinnervation picture of both the PCA and the vocal muscles on the experimental side. The conclusion drawn from this study is that axonal escape, probably from the implantation site, results in an unwanted reinnervation of laryngeal adductor muscles, which neutralize the abducting effect of the PCA muscle during inspiration. This method therefore does not seem to be suitable as a treatment alternative for bilateral recurrent nerve paralysis.

The human posterior cricoarytenoid (PCA) muscle and diaphragm. A histochemical comparison as a basis for reinnervation attempts

PCA (posterior cricoarytenoid) muscles and biopsies from the SCM (sterno-cleidomastoid) muscles as well as the diaphragm were serially sectioned and incubated for myofibrillar ATPase and selected metabolic enzymes. The three main fibre types were present in all muscles, although some PCA muscles seemed to lack IIB fibres. The mean fibre type pattern of the PCA muscle was 57% type I, 36% type IIA and 7% type IIB, as compared with 42% type I, 42% type IIA and 16% type IIB in the diaphragm. All fibre types of the PCA muscle and the diaphragm were significantly more oxidative and less glycolytic than the corresponding SCM muscle fibres. Most striking was the finding of high 3-HBDH activity in the PCA and diaphragm muscle fibres, especially in type I.

Functional results after experimental reinnervation of the posterior cricoarytenoid muscle in dogs

The purpose of the present investigation was to test and compare three different types of experimental posterior cricoarytenoid (PCA) muscle reinnervation. Dogs were subjected to reinnervation by the recurrent nerve itself (self-reinnervation) (n = 6), by the ansa cervicalis nerve (n = 5) or by the phrenic nerve (n = 5). In all but three of the self-reinnervation cases the adductor branch of the nerve was cut and ligated. Three to seven months postoperatively--depending upon the experimental approach--the animals were anesthetized and the function of the vocal cords was tested, visually evaluated and photographed. In the self--reinnervated larynges there were no observable movements on the reinnervated side during quiet inspiration, while during forced inspiration there were small but inconsistent movements. In the larynges reinnervated by the ansa cervicalis nerve no movements could be observed on the reinnervated side during either quiet or forced respiration. In four out of five larynges reinnervated by the phrenic nerve there were larger excursions on the reinnervated side as compared to the normal side during quiet respiration. During forced inspiration the excursions increased on both sides, but relatively more on the normal side. In all experiments indirect electrical stimulation gave large excursions on the experimental side indicating successful reinnervation. It is concluded that the phrenic nerve appears to be the best alternative if reinnervation of the PCA muscle in paralyzed larynges is attempted.

A histochemical evaluation of experimentally reinnervated canine laryngeal muscles

Sixteen dogs underwent different types of experimental reinnervation procedures of the posterior cricoarytenoid (PCA) muscle - reinnervation by the recurrent nerve itself (self-reinnervation) (n = 6), by the ansa cervicalis nerve (n = 5) or by the phrenic nerve (n = 5). After functional evaluation the normal left and the reinnervated right PCA muscles were removed for histochemical analysis. Cryostat sections were incubated for actomyosin ATPase, NADH-TR and alpha-GPDH. All muscles showed microscopical evidence of successful reinnervation. There was a slight change in the muscle fiber type composition in the reinnervated muscle as compared to the normal side. Incubations for the NADH-TR and alpha-GPDH showed less staining intensity in the reinnervated muscles. The histochemical differences between normal and reinnervated muscles were small, however, and probably of minor importance with regard to the function of the muscles.

The histochemistry of the posterior cricoarytenoid (PCA) muscle in the dog, compared with the diaphragm, the sternothyroid and the sternomastoid muscle

The canine posterior cricoarytenoid (PCA) muscle was compared histochemically with pieces of the diaphragm (Dia), an infrahyoid muscle (the sternothyroid, ST), and with a reference skeletal muscle (the sternomastoid, SM) taken from the same animal. The muscle fibre type composition in the PCA, Dia and ST differed very little and showed a slight type II preponderance. In the SM there was a strong type II preponderance. A subgrouping of the type II muscle fibres could not be carried out in any of the muscles. The oxidative activity was greater in the PCA than in the other three muscles and greater in type I than in type II fibres for all muscles except the Dia. In the Dia, some type I fibres had a larger cross-sectional area and showed a greater oxidative activity and contained less glycogen than the rest of the type I fibres in the muscle. These fibres seemed to represent a separate subgroup of type I fibres possibly serving quiet respiration.

Histochemical characteristics of the tensor tympani muscle in relation to the medial gastrocnemius muscle of the cat

Serial 10-micron cryostat cross-sections of the tensor tympani muscle and of the medial gastrocnemius muscle from adult domestic cats were incubated for myofibrillar ATPase, NADH tetrazolium reductase (NADH-TR), succinic dehydrogenase (SDH), malate dehydrogenase (MDH) and menadione-linked alpha-glycerophosphate dehydrogenase (alpha GPDH). The optical density of individual tensor tympani and gastrocnemius muscle fibres after different incubation procedures was measured photometrically. The absorbance values of the tensor tympani fibres were related to the values of the type I, type IIA and type IIB fibres of the gastrocnemius muscle. Only two different types of fibre could be demonstrated in the tensor tympani, one type resembling the type I and another resembling the type IIA of the gastrocnemius muscle. The findings are discussed in relation to other, recent immunohistochemical studies on cat tensor tympani muscle fibres.

Actomyosin ATPase activity of human laryngeal muscles

The muscles from seven human larynxes removed by laryngectomy have been examined for actomyosin ATPase by histochemical methods. The various muscles contained a mixture of ATPase low (type I) and ATPase high (type II) muscle fibres. The thyreoarytenoid muscle had the highest proportion of type II fibres (65%) and the posterior cricoarytenoid muscle had the highest proportion of type I fibres (67%). The other laryngeal muscles had intermediate valves. All human laryngeal muscles had a higher percetage of type I fibres than the corresponding muscles in animals so far examined, a finding which may be related to the development of speech.

Histochemical definition of muscle fibre types in the trunk musculature of a teleost fish (cod, Gadus morhua, L.)

Cryostat sections incubated for myofibrillar ATPase, SDH, LDH, and alpha-GPDH as well as p-phenylene-diamine stained semithin sections were used to define muscle fibre types in the trunk musculature of the cod (Gadus morhua, L.). Three zones (superficial, intermediate, deep) containing different muscle fibre types are present within both epaxial and hypaxial parts of each myomere subjacent to the lateral line. Atypical relations concerning myofibrillar ATPase activity probably reflects instability of myosin during storage of frozen tissue. The histochemical reaction does not distinguish between myofibrillar and mitochondrial ATPase in cod muscle. Based on ATPase and SDH activities, seven different histochemical profiles of muscle fibres can be identified in trunk musculature of this teleost fish. Attempts to homologize these fibre types with those in cyclostomes or those in higher animals proved futile. The higher number of histochemically defined muscle fibre types in cod might be explained by developmental processes and an admixture of immature fibres throughout life.

Contractile properties of muscle: control by pattern of muscle activity in the rat

The denervated slow twitch rat soleus muscle was stimulated electrically for 3-6 weeks with brief trains of stimuli at 100 Hz or long trains at 10 Hz. In both cases the mean stimulation frequency was 2 Hz. Muscles stimulated at 100 Hz acquired several properties characteristic of fast muscle, whereas muscles stimulated at 10 Hz remained slow. The results demonstrate the importance of pattern of muscle activity in determining the contractile properties of muscle.