Novel Pathogenesis of Hypertension and Diastolic Dysfunction Caused by M3R (Muscarinic Cholinergic 3 Receptor) Signaling

Multiple quantitative trait loci for blood pressure (BP) are localized in humans and rodent models. Model studies have not only produced human quantitative trait loci homologues but also provided unforeseen mechanistic insights into the function modality of quantitative trait loci actions. Presently, congenic knockins, gene-specific knockout, and in vitro and in vivo function studies were used in a rat model of polygenic hypertension, DSS (Dahl salt sensitive) rats. One gene previously unknown in regulating BP was detected with 1 structural mutation(s) for each of 2 quantitative trait loci classified into 2 separate epistatic modules 1 and 3. C17QTL1 in epistatic module 2 was identified to be the gene Chrm3 encoding the M3R (muscarinic cholinergic 3 receptor), since a single function-enhancing M3R^T556M conversion correlated with elevated BP. To definitively prove that the enhanced M3R function is responsible for BP changes by the DSS alleles of C17QTL1, we generated a Chrm3 gene-specific rat knockout. We observed a reduction in BP without tachycardia in both sexes, regardless of the amount of dietary salt, and an improvement in diastolic and kidney dysfunctions. All occurred in spite of a significant reduction in M3R-dependent vasodilation. The previously seen sexual dimorphism for C17QTL1 on BP disappeared in the absence of M3R. A Chrm3-coding variation increased M3R signaling, correlating with higher BP. Removing the M3R signaling led to a decrease in BP and improvements in cardiac and renal malfunctions. A novel pathogenic pathway accounted for a portion of polygenic hypertension and has implications in applying new diagnostic and therapeutic uses against hypertension and diastolic dysfunction.

Regulation of vertebrate nervous system alternative splicing and development by an SR-related protein

Alternative splicing is a key process underlying the evolution of increased proteomic and functional complexity and is especially prevalent in the mammalian nervous system. However, the factors and mechanisms governing nervous system-specific alternative splicing are not well understood. Through a genome-wide computational and expression profiling strategy, we have identified a tissue- and vertebrate-restricted Ser/Arg (SR) repeat splicing factor, the neural-specific SR-related protein of 100 kDa (nSR100). We show that nSR100 regulates an extensive network of brain-specific alternative exons enriched in genes that function in neural cell differentiation. nSR100 acts by increasing the levels of the neural/brain-enriched polypyrimidine tract binding protein and by interacting with its target transcripts. Disruption of nSR100 prevents neural cell differentiation in cell culture and in the developing zebrafish. Our results thus reveal a critical neural-specific alternative splicing regulator, the evolution of which has contributed to increased complexity in the vertebrate nervous system.

A fully automated robotic system for microinjection of zebrafish embryos

As an important embodiment of biomanipulation, injection of foreign materials (e.g., DNA, RNAi, sperm, protein, and drug compounds) into individual cells has significant implications in genetics, transgenics, assisted reproduction, and drug discovery. This paper presents a microrobotic system for fully automated zebrafish embryo injection, which overcomes the problems inherent in manual operation, such as human fatigue and large variations in success rates due to poor reproducibility. Based on computer vision and motion control, the microrobotic system performs injection at a speed of 15 zebrafish embryos (chorion unremoved) per minute, with a survival rate of 98% (n = 350 embryos), a success rate of 99% (n = 350 embryos), and a phenotypic rate of 98.5% (n = 210 embryos). The sample immobilization technique and microrobotic control method are applicable to other biological injection applications such as the injection of mouse oocytes/embryos and Drosophila embryos to enable high-throughput biological and pharmaceutical research.

High-frequency chest wall oscillation in ALS: An exploratory randomized, controlled trial

OBJECTIVES

To evaluate changes in respiratory function in patients with ALS after using high-frequency chest wall oscillation (HFCWO).

METHODS

This was a 12-week randomized, controlled trial of HFCWO in patients with probable or definite ALS, an Amyotrophic Lateral Sclerosis Functional Rating Scale respiratory subscale score < or = 11 and > or = 5, and forced vital capacity (FVC) > or = 40% predicted.

RESULTS

We enrolled 46 patients (58.0 +/- 9.8 years; 21 men, 25 women); 22 used HFCWO and 24 were untreated. Thirty-five completed the trial: 19 used HFCWO and 16 untreated. HFCWO users had less breathlessness (p = 0.021) and coughed more at night (p = 0.048) at 12 weeks compared to baseline. At 12 weeks, HFCWO users reported a decline in breathlessness (p = 0.048); nonusers reported more noise when breathing (p = 0.027). There were no significant differences in FVC change, peak expiratory flow, capnography, oxygen saturation, fatigue, or transitional dyspnea index. When patients with FVC between 40 and 70% predicted were analyzed, FVC showed a significant mean decrease in untreated patients but not in HFCWO patients; HFCWO patients had significantly less increased fatigue and breathlessness. Satisfaction with HFCWO was 79%.

CONCLUSION

High-frequency chest wall oscillation was well tolerated, considered helpful by a majority of patients, and decreased symptoms of breathlessness. In patients with impaired breathing, high-frequency chest wall oscillation decreased fatigue and showed a trend toward slowing the decline of forced vital capacity.

Functional relationships of central and peripheral muscle alterations in multiple sclerosis

The functional implications of central motor impairment and peripheral muscle alterations in multiple sclerosis are unclear. Muscle strength, central and peripheral activation, and symptomatic fatigue were investigated in 16 patients with multiple sclerosis (MS) and 18 control subjects. Voluntary and electrically stimulated isometric contractions were obtained from the ankle dorsiflexor muscles. Maximal voluntary contraction (MVC) was 27% lower in MS patients than controls, although electrically stimulated force was similar. Muscle fat-free cross-sectional area (CSA) was similar in both groups. These data indicate central activation impairment in MS. Such impairment in MS was further demonstrated by decreased foot-tap speed, rate of voluntary force development, and central activation ratio. Peripheral activation changes in MS patients were modest. Although stimulated tetanic force was similar, force relaxation was slower in MS patients compared to controls, resulting in a left-shifted force-frequency relationship in MS. Motor function changes were not associated with fatigue but were associated with impaired ambulation. Thus, weakness and walking impairment, but not fatigue, were related to impaired central activation in MS. These findings may help optimize rehabilitation strategies designed to improve function in persons with MS.

Early detection and longitudinal changes in amyotrophic lateral sclerosis by (1)H MRSI

OBJECTIVE

To determine 1) the reproducibility of metabolite measurements by (1)H MRS in the motor cortex; 2) the extent to which (1)H MRS imaging (MRSI) detects abnormal concentrations of N-acetylaspartate (NAA)-, choline (Cho)-, and creatine (Cre)-containing compounds in early stages of ALS; and 3) the metabolite changes over time in ALS.

METHODS

Sixteen patients with definite or probable ALS, 12 with possible or suspected ALS, and 12 healthy controls underwent structural MRI and multislice (1)H MRSI. (1)H MRSI data were coregistered with tissue-segmented MRI data to obtain concentrations of NAA, Cre, and Cho in the left and right motor cortex and in gray matter and white matter of nonmotor regions in the brain.

RESULTS

The interclass correlation coefficient of NAA was 0.53 in the motor cortex tissue and 0.83 in nonmotor cortex tissue. When cross-sectional data for patients were compared with those for controls, the NAA/(Cre + Cho) ratio in the motor cortex region was significantly reduced, primarily due to increases in Cre and Cho and a decrease in NAA concentrations. A similar, although not significant, trend of increased Cho and Cre and reduced NAA levels was also observed for patients with possible or suspected ALS. Furthermore, in longitudinal studies, decreases in NAA, Cre, and Cho concentrations were detected in motor cortex but not in nonmotor regions in ALS.

CONCLUSION

Metabolite changes measured by (1)H MRSI may provide a surrogate marker of ALS that can aid detection of early disease and monitor progression and treatment response.

A preliminary evaluation of a prospective study of pulmonary function studies and symptoms of hypoventilation in ALS/MND patients

There is still no consensus as to which physiologic marker should be used as a trigger for the initiation of non-invasive positive pressure ventilation (NPPV) in patients with amyotrophic lateral sclerosis (ALS). Current practice parameters recommend that the decision to begin treatment be based upon forced vital capacity (FVC) measurements. A prospective, randomized study was performed in 20 ALS patients who had an FVC of 70-100%. Patients received baseline assessments including: ALS functional rating scale-respiratory version (ALSFRS-R), pulmonary symptom scale, Short form 36 (SF-36), FVC%, maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and nocturnal oximetry. Patients were randomized to receive NPPV based upon nocturnal oximetry studies suggesting oxygen desaturation <90% for one cumulative minute ("early intervention") or a FVC <50% ("standard of care"). At enrollment, there was no significant correlation between FVC% and the ALSFRS-R, symptom score, MEP, MIP, or duration of nocturnal desaturation <90%. An increase in the vitality subscale of the SF-36 was demonstrated in 5/6 patients randomized to "early intervention" with NPPV. Our data indicate that FVC% correlates poorly with respiratory symptoms and suggests that MIP and nocturnal oximetry may be more sensitive measures of early respiratory insufficiency. In addition, intervention with NPPV earlier than our current standard of care may result in improved quality of life.

Effects of the early diagnosis of amyotrophic lateral sclerosis on the patient: advantages

Advantages of early diagnoses in amyotrophic lateral sclerosis include validation of symptoms, avoidance of unnecessary procedures, enhanced preparation for disability and medical education. Most importantly, earlier in the course of the disease--while there is a greater motor neuron pool survival--diagnosis would enable earlier treatment intervention.

Conceptual approach to diagnostic delay in ALS: a United States perspective

The mean time from onset of symptoms to confirmation of diagnosis of amyotrophic lateral sclerosis (ALS) in the United States, as elsewhere, is 16-18 months. Delays may arise from the complex referral pathway, caused at least in part by the multiple types of insurance and health-care services available in the United States and also because physicians sometimes attempt to avoid medicolegal responsibility for a very undesirable diagnosis. In addition, initial symptoms are often intermittent and nonspecific and may be denied or not recognized by the patient. In the United States, the primary care physician is increasingly viewed by health maintenance organizations as a gatekeeper, with incentives to keep the diagnosis within the primary care realm. This may lead to misdiagnosis and inappropriate referral. Even after the patient reaches a neurologist, the differential diagnosis of ALS is large and may involve many tests, all of which may incur scheduling and reporting delays. Reluctance to give a bad diagnosis before it is absolutely certain may also cause delay. Delays after diagnosis may be the result of health insurance constraints, the prejudices of the neurologist in favor of or against particular therapies, and the patient's willingness to accept or ability to pay for therapy. Many of these delays may be lessened by both professional and lay educational initiatives to raise awareness of the symptoms of ALS and encourage more rapid presentation and referral to the neurologist. The availability of credible treatment options would undoubtedly encourage physicians to have hope and to seek an earlier diagnosis.

Reduced MTR in the corticospinal tract and normal T2 in amyotrophic lateral sclerosis

The objective of this study was to test the hypothesis that magnetization transfer ratios (MTR) are decreased in the corticospinal tract of patients with amyotrophic lateral sclerosis (ALS); to determine if T2 is increased in corticospinal tract or reduced in motor cortex in ALS; to determine if corticospinal tract MTR correlates with a clinical measure of motor neuron function in ALS. Ten ALS patients and 17 age-matched controls were studied. Double spin echo MRI and 3D gradient echo MRI with and without off-resonance saturation were acquired on each subject. 3D data sets were coregistered and resliced to match the spin echo data set. MTR was calculated for corticospinal and non-corticospinal tract white matter. T2 was calculated for corticospinal and non-corticospinal tract white matter, motor cortex and non-motor cortex. MTR was reduced by 2.6% (p < .02) in corticospinal, but not in non-corticospinal, tract white matter in ALS. There was no difference in T2 in any brain region. The correlation between a clinical measure of motor neuron function and corticospinal tract MTR was statistically significant. These findings are consistent with the known pathology in ALS and suggest that MTR is more sensitive than T2 for detecting involvement of the corticospinal tract. Quantitative MTR of the corticospinal tract may be a useful, objective marker of upper motor neuron pathology in ALS.

Decreased N-acetylaspartate in motor cortex and corticospinal tract in ALS

The primary objectives of this study were to test whether 1) N-acetylaspartate (NAA), a neuronal marker, is reduced in motor cortex and corticospinal-tract (CST) brain regions of ALS patients; and 2) motor cortex NAA correlates to a clinical measurement of upper motor neuron function in ALS patients. Ten probable or definite ALS patients and nine neurologically normal control subjects were studied. Three axial planes of two-dimensional 1H MRSI data were collected, using a single spin-echo multislice sequence (TE140/TR2000). Two of the 1H MRSI planes were positioned superior to the lateral ventricles, and one plane was positioned at the level of the internal capsule. Spectroscopy voxels were selected from motor cortex, frontal cortex, parietal cortex, medial gray matter, centrum semiovale white matter, anterior internal capsule, and posterior internal capsule. Peak integrals were obtained for the three major 1H MRSI singlet resonances, NAA, creatine and phosphocreatine (Cr), and cholines (Cho). Maximum finger-tap rate was used as a clinical measurement of upper motor neuron function. In ALS, brain NAA/(Cho+Cr) was reduced 19% (p=0.024) in the motor cortex and 16% (p=0.021) in the CST (centrum semiovale and posterior internal capsule) regions. NAA/ (Cho+Cr) was not reduced in frontal cortex, parietal cortex, medial gray matter, or anterior internal capsule. There was a significant relation between ALS motor cortex NAA/(Cho+Cr) and maximum finger-tap rate (r=0.80; p=0.014). NAA/(Cho+Cr) was reduced in motor cortex and CST regions and unchanged in other brain regions of ALS patients when compared with controls. These findings are consistent with the known distribution of neuronal loss in ALS. The positive correlation between motor cortex NAA/(Cho+Cr) and maximum finger-tap rate suggests that reduced NAA/(Cho+Cr) is a surrogate marker of motor cortex neuron loss in ALS. These findings support the study of 1H MRSI NAA measurement as an objective and quantitative measurement of upper motor neuron dysfunction in ALS.

Isolation of a goldfish brain cytochrome P450 aromatase cDNA: mRNA expression during the seasonal cycle and after steroid treatment

To investigate the molecular basis and physiological regulation of exceptionally high levels of aromatase (P450arom) activity in the brain of teleost fish, a 2927 bp P450arom cDNA encoding a 510 amino acid protein was isolated from a goldfish brain cDNA library. The brain-derived cDNA had 53% and 61-62% sequence identity when compared with human placental and fish ovarian P450arom forms, respectively, and higher homologies in conserved functional domains. Goldfish brain poly(A) RNA was translatable in vitro to a 56 kDa P450arom immunoprecipitation product. Northern blot analysis using the brain cDNA revealed a major 3.0 kb transcript of high abundance in brain (FB, forebrain > M/HB, mid/hindbrain), but no signal in ovary, testis or liver. P450arom mRNA varied seasonally in brain, with a peak at the onset of gonadal regrowth (February) that preceded the annual rise in enzyme levels and was 4-fold (FB) or 50-fold (M/HB) higher than during reproductive inactivity (July-December). Known markers of neurogenesis and estrogen action in brain (28S rRNA, beta-actin and beta-tubulin transcripts) each had unique seasonal patterns which differed from P450arom mRNA. In vivo steroid treatment showed that estrogen and aromatizable androgen increase FB and M/HB levels of P450arom mRNA 8- and 4-fold, respectively. P450arom mRNA in pituitary and retina had a different regulation. Southern analysis provided no evidence for multiple genes encoding the brain derived cDNA or for brain-specific gene amplification. Results imply that high accumulated levels of P450arom mRNA are the major determinant of high measured enzyme activity in goldfish brain, and that physiological regulation of mRNA expression in the natural environment is mediated by aromatization of androgen to estrogen.

Strength, skeletal muscle composition, and enzyme activity in multiple sclerosis

This study examined functional, biochemical, and morphological characteristics of skeletal muscle in nine multiple sclerosis (MS) patients and eight healthy controls in an effort to ascertain whether intramuscular adaptations could account for excessive fatigue in this disease. Analyses of biopsies of the tibialis anterior muscle showed that there were fewer type I fibers (66 +/- 6 vs. 76 +/- 6%), and that fibers of all types were smaller (average downward arrow26%) and had lower succinic dehydrogenase (SDH; average downward arrow40%) and SDH/alpha-glycerol-phosphate dehydrogenase (GPDH) but not GPDH activities in MS vs. control subjects, suggesting that muscle in this disease is smaller and relies more on anaerobic than aerobic-oxidative energy supply than does muscle of healthy individuals. Maximal voluntary isometric force for dorsiflexion was associated with both average fiber cross-sectional area (r = 0.71, P = 0.005) and muscle fat-free cross-sectional area by magnetic resonance imaging (r = 0.80, P < 0. 001). Physical activity, assessed by accelerometer, was associated with average fiber SDH/GPDH (r = 0.78, P = 0.008). There was a tendency for symptomatic fatigue to be inversely associated with average fiber SDH activity (r = -0.57, P = 0.068). The results of this study suggest that the inherent characteristics of skeletal muscle fibers per se and of skeletal muscle as a whole are altered in the direction of disuse in MS. They also suggest that changes in skeletal muscle in MS may significantly affect function.

Immunolocalization of aromatase- and androgen receptor-positive neurons in the goldfish brain

Full expression of testosterone (T) actions in the brain requires both direct binding to androgen receptors (AR) and in situ aromatization to estradiol (E2). To determine the cellular basis of constitutively high aromatase and AR binding activities in teleost fish brain, and the neuroanatomic location and spatial relations of cells of each type, an immunocytochemical mapping study of goldfish (Carassius auratus) brain was carried out using antibodies to human placental aromatase and human/rat AR peptide and the avidin-biotin-peroxidase technique. Both antibodies specifically labeled cells that were neuronal in appearance and were most numerous in reproductive control centers: medial and ventral telencephalon (TEL) and preoptic and hypothalamic periventricular nuclei. Additional populations of aromatase- and AR-labeled cells were present in the olfactory bulbs, central telencephalon, and stratum periventriculare of the optic tectum. Anti-aromatase, but not anti-AR, labeled fiber tracts and fibrous layers in visual and auditory pathways, and perikarya and processes of premotor neurons known to integrate sensory input (reticulospinal neurons, Mauthner cells). Anti-AR selectively labeled lateral TEL regions, the nucleus ventromedialis thalami, and discrete cell clusters in the medial tegmental nucleus. Aromatase-immunoreactivity (-ir) was primarily cytoplasmic, whereas AR-ir was primarily nuclear, but relative intensity of nuclear vs cytoplasmic labeling with each antibody differed by brain region. Aromatase- and AR-ir cells were not obviously more numerous in goldfish brain than previously seen in birds and mammals, suggesting that enhanced expression occurs on a per cell basis. We conclude that T exerts its actions coordinately via direct and indirect pathways in most brain regions but independently via AR- or aromatase-mediated mechanisms in selected areas. These studies point to a wide role for androgen in modulating primary sensory signals as well as in classical reproductive processes.

Clinical trials of riluzole in patients with ALS. ALS/Riluzole Study Group-II

Two double-blinded, placebo-controlled clinical trials of riluzole have now been carried out in more than 1,100 patients with ALS. The results of both studies show a modest benefit in prolonging survival that is statistically significant. These results led to the availability of this drug by the Food and Drug Administration for use in the United States beginning in early 1996. This is the first drug that has been available for ALS. It begins a new era in both basic and clinical research in an attempt to find a cure for this disease.

Immunocytochemical and biochemical evidence for aromatase in neurons of the retina, optic tectum and retinotectal pathways in goldfish

Using an animal model in which neural aromatase is apparently overexpressed (the goldfish, Carassius auratus) and an anti-human placental antibody which specifically crossreacts with goldfish brain aromatase, aromatase-immunoreactive neuronal cell bodies and fibers have been localized within the retina. These include a subset of horizontal cells, bipolar cells, and amacrine cells of the inner nuclear layer, some fibers of the outer and inner synaptic layers and certain cells of the ganglion cell layer; photoreceptors were never labeled. Some ganglion cell projections to the brain via the optic nerve and optic tract were aromatase-positive, as were small neurons of the stratum periventriculare (SPV) and fibers of two other strata of the optic tectum. Aromatase activity, as measured by [3H]androgen by tissue homogenates and cell cultures, confirmed the presence of aromatase in retina and in brain regions containing the optic tectum. This localization of the rate-limiting enzyme in estrogen biosynthesis suggests that neuroestrogen derived from circulating androgen m ay modulate transmission and integration of visual information important for reproduction in this species.

Molecular and cellular physiology of aromatase in the brain and retina

Due to exceptionally high brain aromatase activity, teleost fish are advantageous for studying neural aromatase regulation, localization, and physiology. To determine the molecular mechanism of enhanced expression, we have isolated, cloned and sequenced a 3 kb full-length aromatase cDNA from a goldfish (Carassius auratus) brain library using a human placental aromatase cDNA as probe. The deduced sequence of goldfish aromatase is 510 amino acids (predicted Mw, 58 kDa) with 69% overall sequence similarity, when compared to human placental aromatase, and higher homologies in presumptive functional domains. A major 3 kb mRNA species was abundant in brain and low or non-detectable in non-neural tissues, reflecting the order of enzyme activities. To determine the cellular basis of high enzyme activity in goldfish brain, a human placental aromatase antibody was used to immunolocalize labeled cells. This antibody immunoprecipitated a single 56 kDa in vitro translation product of goldfish brain poly(A+)RNA and revealed discrete clusters of intensely stained neurons, processes, and terminals concentrated in, but not limited to, reproductive brain centers. Close proximity of aromatase- and androgen receptor-positive neurons in certain regions provides anatomic evidence of a functional relationship between direct and indirect pathways of neural androgen action. Aromatase-positive neurons and fibers formed interconnected networks in novel loci (e.g. retina-->optic tract-->optic tectum), and catalytic activity was confirmed biochemically in these tissues, indicating that neuroestrogen may have a role in visual input and integration. Availability of goldfish-specific nucleotide and antibody probes will facilitate further studies using this model.

IAA Oxidase Inhibitors from Normal and Mutant Maize Plants

Extracts of maize (Zea mays L.) plants contain substances which, in vitro, inhibit an indoleacetic acid (IAA) oxidase enzyme from maize. The extracts can be freed of inhibitors by dialysis or by passage through columns of polyvinylpyrrolidone powder. Inhibitor-free extracts contain an IAA oxidase enzyme which requires a phenolic co-factor and is stimulated by Mn(2+).IAA oxidase inhibitor and total phenol levels were compared for normal maize and for the maize mutant Knotted (Kn). In plants up to 18 days old the level of heat stable, water soluble IAA oxidase inhibitors increases with increasing dosage of the Kn allele. Increased inhibitor content is accompanied, but not paralleled, by increased content of total phenols. Although several inhibitors are present in crude extracts, most inhibition can be attributed to 1 compound. This compound is not destroyed by horseradish peroxidase in the absence of IAA. At pH 3.5 it is not extracted into ether, but it is rendered ether-extractable by incubation in 2 n KOH for 5 hr at room temperature. This compound is tentatively identified as an ester of ferulic acid and some unknown moiety.