Lack of association between apolipoprotein E genotype and sporadic amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neuro-degenerative disorder with both sporadic and familial forms. Approximately 20% of autosomal dominant ALS is caused by mutations in the Cu/Zn superoxide dismutase (SOD1) gene. The causes of the remaining forms of ALS are unknown. The apolipoprotein E (APOE) gene is a known genetic risk factor for Alzheimer disease (AD), another neuro-degenerative disease. The APOE-4 allele increases risk and decreases age at onset in AD. Studies examining ALS and APOE have failed to show a significant effect of APOE on overall risk in ALS. Studies examining the effect of APOE-4 on site of onset in ALS (bulbar or limb) have been contradictory, with some studies showing an APOE association with bulbar onset and others showing no effect. Sample size was limited in these previous reports, particularly with respect to the number of bulbar onset cases (n = 33, 34 and 53). The present study examines a large collaborative data set of ALS patients (n = 363; 95 with bulbar onset) and age-matched neurologically normal controls. The results for these data showed no significant differences in the percentage of subjects with the APOE-4/4 and APOE-4/X genotypes (X = APOE-2 or APOE-3) when comparing cases and controls in both the overall data set or in the data set stratified by site of onset. Similarly, logistic regression analysis in the overall and stratified data set while controlling for sex showed no increase or decrease in risk of ALS associated with the APOE-4 allele. In addition, there were no significant differences in age at onset between patients with APOE-X/X, and APOE-4/4 or APOE-4/X genotypes, overall or stratified by site of onset. We conclude based on these data that the APOE gene is not a major genetic risk factor for site of onset in ALS.

Lack of detection of enteroviral RNA or bacterial DNA in magnetic resonance imaging-directed muscle biopsies from twenty children with active untreated juvenile dermatomyositis.

OBJECTIVE: To investigate for the presence of increased titers of circulating antibody to putative infectious agents and for detectable viral RNA or bacterial DNA in children with active recent-onset juvenile dermatomyositis (DM). METHODS: Magnetic resonance imaging-directed muscle biopsies were performed in 20 children with active, untreated, recent-onset juvenile DM and in age-matched children with neurologic disease. Sera were tested for complement-fixing antibody to Coxsackievirus B (CVB), influenza A and B, parainfluenza 1 and 3, Mycoplasma pneumoniae, mumps, respiratory syncytial virus, and Reovirus; and by immunofluorescence for IgG antibody to Toxoplasma gondii cytomegalovirus and IgM antibody to Epstein-Barr virus. Muscle from juvenile DM patients and control children, CD-1 Swiss mice with and without CVB1 infection, and viral stock positive for CVB1-6 were tested using reverse-transcriptase polymerase chain reaction with 5 primer sets, 4 probes (1 Coxsackievirus, 3 Enterovirus), and universal primers for DNA. RESULTS: No increased antibody, viral RNA, or bacterial DNA was present in the juvenile DM patients or the control children. CONCLUSION: Juvenile DM may be triggered by unidentified agent(s) in the genetically susceptible host.

Motor neuron degeneration in mice that express a human Cu,Zn superoxide dismutase mutation.

Mutations of human Cu,Zn superoxide dismutase (SOD) are found in about 20 percent of patients with familial amyotrophic lateral sclerosis (ALS). Expression of high levels of human SOD containing a substitution of glycine to alanine at position 93--a change that has little effect on enzyme activity--caused motor neuron disease in transgenic mice. The mice became paralyzed in one or more limbs as a result of motor neuron loss from the spinal cord and died by 5 to 6 months of age. The results show that dominant, gain-of-function mutations in SOD contribute to the pathogenesis of familial ALS.

Effects of continuous low-frequency pacing on immature canine diaphragm.

Although diaphragm pacing has been shown to be a practical method of supporting ventilation in children, its usefulness has been limited because of concern that continuous (24 h/day) diaphragm pacing would fatigue and damage the diaphragm. We examined the functional and structural effects of continuous low-frequency diaphragm pacing on the left hemidiaphragm of five immature dogs aged 65 +/- 2 (SD) days at onset of pacing. Stimulus parameters approximated those required to pace infants: frequency 11.1 Hz, inspiratory time 810 ms, and respiratory rate 20 breaths/min. Animals were paced 24 h/day for 24-28 days. Paced tidal volumes and airway occlusion pressures were unchanged at low (less than 15 Hz) stimulus frequencies but were reduced at high (greater than 20 Hz) stimulus frequencies. Although histologically the paced hemidiaphragms appeared normal, histochemical studies showed a conversion from a mixture of type I (54%) and type II (46%) fibers to a uniform population of type I fibers with high oxidative enzyme activity. Transformation of muscle type was also demonstrated by pyrophosphate gel electrophoresis; fast and slow isomyosin bands were noted in control specimens, whereas only slow isomyosin was identified in paced specimens. Thus, in immature dogs, continuous low-frequency pacing affects both function and structure of the diaphragm.

Changes in respiratory burst activity during human monocyte differentiation in suspension culture.

Monocytes undergo a process of differentiation following their accumulation into extravascular spaces. This process has been examined previously by culturing monocytes and identifying changes in cell morphology, metabolism, and function over time. The present study was designed to characterize mononuclear phagocyte respiratory burst activity as related to differentiation by measuring chemiluminescence and superoxide anion generation in cultured human monocytes. Monocytes maintained in Teflon vials for up to 12 days increased in size, were positive for nonspecific esterase, and retained the ability to ingest latex particles. During culture, however, cells progressively lost their peroxidase-positive granules. When monocytes were cultured for one or five days, they elicited less than 50% of the luminol-enhanced chemiluminescence produced by fresh monocytes following PMA stimulation. By day 7, less than 20% of day 0 PMA-elicited chemiluminescence was observed. A comparable loss of serum-opsonized zymosan-induced chemiluminescence occurred during monocyte culture. Since it is recognized that luminol-enhanced chemiluminescence is, in large part, dependent upon myeloperoxidase and since differentiated mononuclear phagocytes are only minimally peroxidase-positive, cultured monocyte respiratory burst activity was also assessed by directly quantifying superoxide anion generation. When monocytes were cultured for three or five days, they elicited 38% more superoxide anion than did fresh monocytes following PMA stimulation. At day 7, PMA-induced superoxide anion release was comparable to day 0 levels. These data indicate that monocytes allowed to differentiate under nonadherent conditions maintain the ability to undergo a respiratory burst response as measured by superoxide anion release, but they concomitantly lose peroxidase-dependent luminol-enhanced chemiluminescence. In this regard, monocytes cultured in suspension metabolically resemble macrophages that have undergone differentiation within sites of inflammation.

Hypothalamo-adenohypophyseal-thyroid interrelationships in the developing chick embryo. VII. Immunocytochemical demonstration of thyrotrophin-releasing hormone.

Thyrotrophin-releasing hormone (TRH) was demonstrated immunocytochemically in the infundibulum of the chick embryo as early as Day 4.5 of incubation. From Days 4.5 through 19.5 of embryonic development there is a gradual increase within the developing hypothalamus in the number of TRH-positive perikarya as well as the amount of immunoreactive-TRH (IR-TRH) per cell. There are no abrupt changes in either parameter during the critical time period (Days 10.5-13.5 of incubation) in the maturation of the pituitary-thyroid axis. Thus, although TRH is probably not directly responsible for the dramatic increase in the number of thyrotrophin-producing cells which occurs in the pars distalis of 10.5- to 11.5-day-old embryos (R. C. Thommes, J. B. Martens, W. E. Hopkins, J. Caliendo, M. J. Sorrentino, and J. E. Woods (1983). Gen. Comp. Endocrinol. 51, 434-443) the marked change in the activity of the pituitary-thyroid unit at this time may well reflect the response of these newly differentiated thyrothrophs to low levels of plasma TRH. This hypothesis is supported by the observations that between Days 10.5 and 11.5 the hypothalamic-adenohypophyseal-thyroid (HAT) axis is first responsive to cold (R. C. Thommes, J. B. Martens, J. B. Hopkins, D. A. Griesbach, D. J. Williams, M. J. Sorrentino, P. Wernke, and J. E. Woods. In "Proceedings, Ninth International Symposium on Comparative Endocrinology Hong Kong, 7-11 December 1981" (B. Lofts, ed.). Hong Kong Univ. Press, Hong Kong, in press) and also that the pituitary-thyroid unit exhibits a marked increase in its sensitivity to exogenous TRH (R. C. Thommes, D. J. Williams, and J. E. Woods (1984). Gen. Comp. Endocrinol. 55, 275-279).

Hypothalamo-adenohypophyseal-thyroid interrelationships in the chick embryo. IV. Immunocytochemical demonstration of TSH in the hypophyseal pars distalis.

The cells that synthesize thyroid-stimulating hormone (TSH) in the pars distalis of the chick embryo were identified immunocytochemically (immunoperoxidase and immunofluorescence) using anti-bovine TSH-beta and anti-human TSH-beta sera. TSH cells are first demonstrable on Day 6.5 of incubation. By Day 11.5, when the two lobes (rostral and caudal) of the pars distalis are easily recognized, TSH cells are confined exclusively to the rostral lobe. TSH cells identified by means of immunofluorescence were stained with the periodic acid-Schiff component of the performic acid-Alcian blue periodic acid-Schiff's Orange G stain. Immunoreactive TSH cells in the pares distales of Day 13.5 chick embryos, injected at 5.5 days of incubation with thiourea, were more intensively stained than their normal counterparts. The marked change in immunocytochemically demonstrable TSH on Day 11.5 corresponds with physiological and morphological events occurring within the hypothalamus, adenohypophysis, and the thyroid gland of the developing chick during this midincubational (midgestational) period. The data suggest that not only is hypophyseal TSH present in greater quantities after Day 10.5, but that adenohypophyseal synthesis and secretion of TSH may be stimulated by another factor (hypothalamic TRH) at this time, signaling functional maturation of the hypothalamo-adenohypophyseal-thyroid axis.