Effects of motilin on intracellular free calcium in cultured smooth muscle cells from the antrum of neonatal rats

AIM

The aim of this study was to determine the effects of motilin on [Ca(2+)](i) regulation and its underlying molecular mechanism in cultured antral smooth muscle cells (ASMCs).

METHODS

Antral cells were isolated and cultured from neonatal rats, and then the [Ca(2+)](i) in these cells was evaluated by calcium fluorescent probe Fluo-3/AM on a laser scanning confocal microscope.

RESULTS

We show that motilin dose-dependently increased [Ca(2+)](i) concentration in cultured ASMCs. Pre-incubation of cells with either the calcium antagonist verapamil (10(-5) mol L(-1)) or the calcium chelator Egtazic (EGTA, 0.1 mmol L(-1)) significantly suppressed motilin (10(-6) mol L(-1)) induced [Ca(2+)](i) increase as indicated by fluorescent intensity. Interestingly, after mixing with the non-selective intracellular calcium release blocker TMB-8 (10(-5) mol L(-1)), guanosine triphosphate regulatory protein antagonist NEM (10(-5) mol L(-1)), phospholipase C (PLC) inhibitor compound 48/80 (1.2 microg mL(-1)) and ryanodine at high concentration (10(-5) mol L(-1)), the motilin-induced [Ca(2+)](i) increase was only partially blocked. The protein kinase C inhibitor d-sphingosine (10(-6) mol L(-1)), however, did not show any inhibitory effect on motilin-induced [Ca(2+)](i) elevation.

CONCLUSIONS

Our study suggests that motilin-stimulated [Ca(2+)](i) elevation in ASMCs is probably due to sustained extracellular Ca(2+) influx and Ca(2+) release from Ca(2+) stores via inositol tris-phosphate receptors and ryanodine receptors. Specifically, motilin-induced [Ca(2+)](i) release is accompanied with guanosine triphosphate-binding protein-coupled receptor-PLC-inositol tris-phosphate signalling cascades.

Specific mutations in methyl-CpG-binding protein 2 confer different severity in Rett syndrome

OBJECTIVE

To determine if a relationship exists between the clinical features of Rett syndrome, an X-linked dominant neurodevelopmental disorder, and specific mutations in MECP2.

METHOD

Cross-sectional study of 245 girls and women with typical Rett syndrome seen between 1990 and 2004 in tertiary academic outpatient specialty clinics and who had complete MECP2 mutation analysis. A structured clinical evaluation was completed for each participant. The results were grouped by MECP2 mutation and compared.

RESULTS

Participants with the R133C mutation are less severely affected than those with R168X or large DNA deletions (p < 0.05). Likewise, individuals with the R168X mutation are more severely affected than those with R294X and late carboxy-terminal truncating mutations (p < 0.05). Clinical differences are notable in ambulation, hand use, and language (p < 0.004), three cardinal features of Rett syndrome. Individuals with R168X are less likely to walk (p = 0.008), retain hand use (p = 0.002), or use words (p = 0.001). In contrast, those with carboxy-terminal truncations are more likely to walk (p = 0.007) and use words (p < 0.001). The R306C mutation, previously found to confer milder features, adversely affects only one clinical feature, language (p < 0.05).

CONCLUSIONS

Specific mutations in MECP2 confer different severity. These results allow the design of therapies targeted toward the amelioration of expected problems. Furthermore, the distinct effects of MECP2 mutations on clinical severity must be considered in clinical intervention trials.

Clinical phenotype of Brazilian families with spinocerebellar ataxia 10

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant ataxia caused by an ATTCT repeat expansion in an intron of the SCA10 gene. SCA10 has been reported only in Mexican families, in which the disease showed a combination of cerebellar ataxia and epilepsy. The authors report 28 SCA10 patients from five new Brazilian families. All 28 patients showed cerebellar ataxia without epilepsy, suggesting that the phenotypic expression of the SCA10 mutation differs between Brazilian and Mexican families.

Comparison of effects of acetylcholine on electromechanical characteristics in guinea-pig atrium and ventricle

The direct negative effects of acetylcholine (ACh) on guinea-pig atria and ventricles were investigated using standard microelectrodes, a force transducer and a video edge-detection system. It was found that: (1) ACh (at 0.001-100 microm) decreased the force of contraction and shortened the action potential duration (APD) in both atria and ventricles in a concentration-dependent manner, and that the atria were more sensitive to ACh than the ventricles; and (2) the direct negative inotropic effect of ACh (1 microm) on an isolated cardiac cell was similar to that on the isolated myocardium. But this effect was not present in all isolated ventricular cells, while all the atrial cells responded to ACh. In conclusion, ACh had direct inhibitory effects on both atrial and ventricular tissue and myocytes, although the effects were greater in atria than in ventricles; and the negative inotropic effect of ACh was closely related to the shortening of the APD.

Analysis of expressed sequence tag loci on wheat chromosome group 4

A total of 1918 loci, detected by the hybridization of 938 expressed sequence tag unigenes (ESTs) from 26 Triticeae cDNA libraries, were mapped to wheat (Triticum aestivum L.) homoeologous group 4 chromosomes using a set of deletion, ditelosomic, and nulli-tetrasomic lines. The 1918 EST loci were not distributed uniformly among the three group 4 chromosomes; 41, 28, and 31% mapped to chromosomes 4A, 4B, and 4D, respectively. This pattern is in contrast to the cumulative results of EST mapping in all homoeologous groups, as reported elsewhere, that found the highest proportion of loci mapped to the B genome. Sixty-five percent of these 1918 loci mapped to the long arms of homoeologous group 4 chromosomes, while 35% mapped to the short arms. The distal regions of chromosome arms showed higher numbers of loci than the proximal regions, with the exception of 4DL. This study confirmed the complex structure of chromosome 4A that contains two reciprocal translocations and two inversions, previously identified. An additional inversion in the centromeric region of 4A was revealed. A consensus map for homoeologous group 4 was developed from 119 ESTs unique to group 4. Forty-nine percent of these ESTs were found to be homoeologous to sequences on rice chromosome 3, 12% had matches with sequences on other rice chromosomes, and 39% had no matches with rice sequences at all. Limited homology (only 26 of the 119 consensus ESTs) was found between wheat ESTs on homoeologous group 4 and the Arabidopsis genome. Forty-two percent of the homoeologous group 4 ESTs could be classified into functional categories on the basis of blastX searches against all protein databases.

Dermatome setting for autografts to cover INTEGRA

Using the INTEGRA Dermal Regeneration Template requires the outer silastic layer to be replaced with an autograft. We followed the manufacturer's directions for epidermal autografting and frequently obtained shredded, useless grafts, therefore, it seemed important to determine the proper dermatome setting. We evaluated dermatome settings from 0.002 to 0.012 inches. First, with feeler gauges, we verified the dermatome settings. Second, we harvested skin at various dermatome settings and measured the thickness histologically. We found that 1) the dermatome settings are reasonably accurate; 2) harvesting useful sheets at 0.002 and 0.004 inches is virtually impossible; 3) the variability of histologic graft thickness is enormous; and 4) a dermatome setting of 0.006 inches yields useful grafts. We no longer use the term epidermal autografting but rather ultrathin split-thickness grafting. To harvest these grafts, we now merely set the dermatome to 0.006 inches and make whatever midcourse corrections are necessary to obtain translucent grafts.

Dermatome setting for autografts to cover INTEGRA

Using the INTEGRA Dermal Regeneration Template requires the outer silastic layer to be replaced with an autograft. We followed the manufacturer's directions for epidermal autografting and frequently obtained shredded, useless grafts, therefore, it seemed important to determine the proper dermatome setting. We evaluated dermatome settings from 0.002 to 0.012 inches. First, with feeler gauges, we verified the dermatome settings. Second, we harvested skin at various dermatome settings and measured the thickness histologically. We found that 1) the dermatome settings are reasonably accurate; 2) harvesting useful sheets at 0.002 and 0.004 inches is virtually impossible; 3) the variability of histologic graft thickness is enormous; and 4) a dermatome setting of 0.006 inches yields useful grafts. We no longer use the term epidermal autografting but rather ultrathin split-thickness grafting. To harvest these grafts, we now merely set the dermatome to 0.006 inches and make whatever midcourse corrections are necessary to obtain translucent grafts.

[Use of ultrasonography to evaluate carotid atherosclerosis and hemodynamics]

One hundred and one cases of carotid atherosclerosis(CAS) were diagnosed by ultrasonography. The intermediate(IMT) of common carotid endomembrane in CAS group was much thicker than that in the healthy group(P < 0.01). There was no significant difference between the two groups in the peak velocity in systolic stage(MAX), the velocity in diastolic stage(MIN), resistance index(RI) and vessel size. The atheromatous plagues were usually flat plaques, seen at the bifurcation of common carotid artery. They belong to early pathological changes. It seems that the plaques don't affect MAX, MIN and RI of the common carotid artery.

Cones of skin occur where hypertrophic scar occurs

Hypertrophic scarring is devastating for the patient, however the pathophysiology and treatment remain unknown after decades of research. The process follows deep dermal injury, occurs only on certain body parts, does not occur in the early fetus or in animals, and is a localized event. This suggests that an anatomic structure in human, deep dermis may be involved. The dermis is a matrix perforated by cones containing many structures including skin appendages and fat domes. We hypothesized that studying the cones might reveal a structure related to scarring. We examined tangential wounds from various body parts on human cadavers along with skin histology from various human body parts, the early fetus, partial thickness burns, hypertrophic scars, and two other species-rats and rabbits. We found that the cones may in fact be the structure. They exist where hypertrophic scar occurs-cheek, neck, chest, abdomen, back, buttock, arm, forearm, dorsal hand, thigh, leg, dorsal foot, helix and ear lobe. They do not exist where hypertrophic scar does not occur-scalp, forehead, concha, eyelid, palm, early fetus, and in rat, or rabbit. It also became apparent that the cones have been omitted from most considerations of skin histology. We suggest that the cones need to be studied in relation to hypertrophic scarring and restored to skin diagrams.

Absence of aquaporin-4 water channels from kidneys of the desert rodent Dipodomys merriami merriami

Recently, we found that aquaporin-4 (AQP4) is expressed in the S3 segment of renal proximal tubules of mice but not in rat proximal tubules. Because mice have relatively larger papillae than rats, it was proposed that the renal distribution of AQP4 in various species could be related to their maximum urinary concentrating ability. Therefore, kidneys and other tissues of Merriam's desert kangaroo rat, Dipodomys merriami merriami, which produce extremely concentrated urine (up to 5,000 mosmol/kgH(2)O), were examined for AQP4 expression and localization. Contrary to our expectation, AQP4 immunostaining was undetectable in any region of the kidney, and the absence of AQP4 protein was confirmed by Western blotting. By freeze fracture electron microscopy, orthogonal arrays of intramembraneous particles (OAPs) were not detectable in plasma membranes of principal cells and proximal tubules. However, AQP4 protein was readily detectable in gastric parietal and brain astroglial cells. Northern blotting failed to detect AQP4 mRNA in kangaroo rat kidneys, whereas both in situ hybridization and RT-PCR experiments did reveal AQP4 mRNA in collecting ducts and proximal tubules of the S3 segment. These results suggest that renal expression of AQP4 in the kangaroo rat kidney is regulated at the transcriptional or translational level, and the absence of AQP4 may be critical for the extreme urinary concentration that occurs in this species.

Imaging of dopamine transporters with technetium-99m TRODAT-1 and single photon emission computed tomography

The authors wanted to evaluate the usefulness of 99Tcm-TRODAT-1 as an imaging agent for measuring changes in dopamine transporter concentrations in Parkinson disease (PD) and correlate the findings to the severity of the disease as measured by the Hoehn and Yahr scale (H/Y). Twenty-two healthy volunteers and 27 patients with PD of H/Y stage I-IV were evaluated. Acquisitions were performed 2 hours after injection of 99Tcm-TRODAT-1. Regions of interest were drawn over the striatum and the cerebellum, and the ratios of striatum-to-cerebellum (ST/CB) were calculated. Patients with PD showed a significant decrease in the striatal uptake of 99Tcm-TRODAT-1 compared to healthy volunteers, and the ST/CB ratios were closely related to the stage of PD. The present study demonstrates that it is possible to visualize and quantify changes in dopamine transporter in the striatum of patients with PD using 99Tcm-TRODAT-1 and SPECT with good correlation to H/Y stage and unified Parkinson's disease rating scale (UPDRS) scale.

Evolutionarily conserved features of the arginine attenuator peptide provide the necessary requirements for its function in translational regulation

Neurospora crassa arg-2 mRNA contains an evolutionarily conserved upstream open reading frame (uORF) encoding the Arg attenuator peptide (AAP) that confers negative translational regulation in response to Arg. We examined the regulatory role of the AAP and the RNA encoding it using an N. crassa cell-free translation system. AAPs encoded by uORFs in four fungal mRNAs each conferred negative regulation in response to Arg by causing ribosome stalling at the uORF termination codon. Deleting the AAP non-conserved N terminus did not impair regulation, but deletions extending into the conserved region eliminated it. Introducing many silent mutations into a functional AAP coding region did not eliminate regulation, but a single additional nucleotide change altering the conserved AAP sequence abolished regulation. Therefore, the conserved peptide sequence, but not the mRNA sequence, appeared responsible for regulation. AAP extension at its C terminus resulted in Arg-mediated ribosomal stalling during translational elongation within the extended region and during termination. Comparison of Arg-mediated stalling at a rare or common codon revealed more stalling at the rare codon. These data indicate that the highly evolutionarily conserved peptide core functions within the ribosome to cause stalling; translational events at a potential stall site can influence the extent of stalling there.

[The role of PMNs in early progressive injury of deep partial-thickness burn wound]

OBJECTIVE

To examine the role of polymorphonuclear neutrophils (PMNs) in early progressive injury of deep partial-thickness burn wound.

METHODS

After deep partial-thickness burn, the count of PMNs in beripheral circulation, activity of myeloperoxidase (MPO) and content of MDA in wound tissue of Spraque Dawley rats, were measured. Sections of wound biopsies were stained with Masson's thrichromatic staining and anti-vimentin immunohistopathologic staining for identifying the injured tissue.

RESULTS

PMNs counts increased immediately and reached a peak at 4 h postburn, and MPO activity peaked at 24 h postburn. MDA content was lowe at 0.5 h and higher at 48 h postburn than that of normal control. Histologic analysis showed that there was more necrotic tissue at 48 hr postburn than that at 24 h.

CONCLUSION

It was after 24 h postburn that PMNs induced tissue damage. The results suggest that intervention of PMNs adhesion should be under taken in about 4 h after thermal injury and anti-oxidizing agent should be given before 24 h postburn in order to prevent early progressive injury to the wound.

The preclinical pharmacologic study of dopamine transporter imaging agent [99mTc]TRODAT-1

The purpose of this study was to investigate the pharmacologic characteristics of TRODAT-1 (2beta-((N,N'-bis(2-mercaptoethyl)ethylene diamino)methyl), 3beta-(4-chlorophenyl)tropane) labeled with [99mTc] as an imaging agent for dopamine transporter (DAT). Radiochemical purity of [99mTc]TRODAT-1 was over 90%. The partition coefficients in octanol and buffer were 2.12 and 2.19 at pH 7.0 and 7.4, respectively. Animal studies have been performed in rats, rabbits, and normal and hemi-Parkinsonian model monkeys. Biodistribution displayed moderate uptake in rat brain (0.28 %ID/organ at 2 min) and the striatal uptake was 0.193, 0.142, and 0.136 %ID/g at 2, 60, and 120 min, respectively. The ratios of striatal/cerebellar (ST/CB) uptake were 2.4, 4.45, and 2.45 %ID/g at 60, 120, and 240 min, respectively. The major radioactivity was excreted by the hepatobiliary system. Blood clearance kinetics was performed in rabbits, and the initial half-life of 1.18 min and late half-life of 367.8 min were obtained. Brain single photon emission computed tomography imaging studies in normal monkeys showed the ratios of ST/CB uptake were 1.56-2.0 %ID/g and indicated that both uptake and retention in the striatal area were associated with the DAT. The imaging of hemi-Parkinsonian model monkeys also displayed the expected selectivity, the highest uptake being observed in the basal ganglia area of the normal side. Thereby, it is suggested that [99mTc]TRODAT-1 is a safe and useful imaging agent for localization of the presynaptic DAT in the brain.

Pharmacology study of the neutral myocardial imaging agent technetium-99m-N(NOEt)2

OBJECTIVE

The biological properties of a new neutral myocardial imaging agent 99mTcN(NOEt)2 were evaluated.

METHODS

Blood clearance in rabbits, biodistribution in rats, and initial myocardial imaging in dogs were performed.

RESULTS

Radiochemical purity of 99mTcN(NOEt)2 was more than 90% and stable for 6 h at room temperature. Blood disappearance was analyzed with a biexponential model and T1/2(alpha) = 2.53 min, T1/2(beta) = 330 min and CI = 378 ml/h were obtained. Biodistribution studies demonstrated that 99mTcN(NOEt)2 localized selectively in the rat myocardium. Cardiac uptakes were 4.69, 4.20, 3.95 and 3.43% ID/g at 5, 30, 60 and 90 min postinjection, respectively. The mean heart-to-lung activity ratios were 1.69, 2.40 and 2.55 at 10 min, 30 min and 60 min postinjection, respectively.

CONCLUSION

Technetium-99m-N(NOEt)2 exhibited favorable stability and biological properties. Further study in humans is required.