Metastatic alveolar rhabdomyosarcoma on the fine-needle aspiration cytology of cervical lymph node in an elderly patient, with FISH confirmation: A case report.

INTRODUCTION: Alveolar rhabdomyosarcoma (RMS) usually occurs in adolescents and young adults, and most frequently arises in the extremities. CASE REPORT: We present a rare case of metastatic alveolar RMS from a nasal primary to cervical lymph nodes (LNs) in an elderly patient, diagnosed on the fine-needle aspiration (FNA) biopsy. Smears showed malignant round cells featuring focal rhabdoid appearance, with rhabdomyoblastic differentiation further supported by immunocytochemical stains. Diagnosis of alveolar RMS was confirmed by fluorescence in situ hybridization (FISH) identifying FOXO1 gene involvement with dual colour break-apart probes at locus 13q14. DISCUSSION: The differential diagnosis for a small round blue cell tumour in the elderly generally includes metastatic small cell carcinoma, lymphoma, malignant melanoma, RMS, desmoplastic small round cell tumour and Ewing's sarcoma/primitive neuroectodermal tumour. Subtle morphological analysis and expression pattern of immunostaining for skeletal muscle differentiation led to the diagnosis of RMS. Cytogenetic testing on the FOXO1 gene rearrangement helps definite subtyping of alveolar RMS.

A two-year follow-up of surgical and non-surgical treatments in patients with masticatory muscle tendon-aponeurosis hyperplasia.

This study re-examined the usefulness of surgery for the management of masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) through a comparison of the outcomes between patients who underwent surgery and those who did not. The duration of follow-up was 2 years. Twenty-eight patients who attended the study hospital and were given a diagnosis of MMTAH were included. Nineteen patients underwent surgery (surgical group) and nine patients were instructed to open their mouths wide once a day and did not undergo surgery (non-surgical group). Maximum mouth opening, impairment of daily activities, satisfaction, and the status of mouth opening training were evaluated after surgery. The mean increase in mouth opening after 2 years was 20.2mm in the surgical group and 2.4mm in the non-surgical group. Adequate mouth opening training led to satisfactory results 2 years postoperative, and sustained mouth opening training for 6 months after surgery was a key factor for obtaining good outcomes. The general condition and personality of individual patients should be evaluated carefully before surgery to estimate whether or not they can endure the pain associated with postoperative mouth opening training. The results of this study suggest that the surgical procedure is useful for the management of MMTAH.

Synchronous papillary thyroid carcinoma and medullary thyroid carcinoma - a pitfall waiting to happen.

Papillary thyroid carcinoma (PTC) is the most common thyroid carcinoma and is derived from thyroid follicular cells. In contrast, medullary thyroid carcinoma (MTC) is rare and originates from the parafollicular C-cells. Synchronous occurrence of these two carcinomas is uncommon and occurs as either discrete lesions or as a mixed lesion. The current case report describes a 50-year-old woman with synchronous multiple discrete MTC and PTC with lymph nodes metastasis. Pathologists and treating physicians should be aware of the synchronous coexistence of these entities to avoid possible misdiagnosis.

Detection of Francisella tularensis and analysis of bacterial growth in ticks in Japan.

UNLABELLED: Francisella tularensis is distributed in the Northern hemisphere and it is the bacterial agent responsible for tularaemia, a zoonotic disease. We collected 4 527 samples of DNA from ticks in Japan, which were then analysed by real-time PCR and nested PCR. Francisella DNA was detected by real-time PCR in 2·15% (45/2 093) of Ixodes ovatus, 0·66% (14/2 107) of I. persulcatus, 8·22% (6/73) of I. monospinosus and 0·72% (1/138) of Haemaphysalis flava specimens. Finally, Francisella DNA was detected by nested PCR in 42 and five samples I. ovatus and I. persulcatus, respectively, which were positive according to real-time PCR. Phylogenetic analysis showed that the sequence from I. ovatus and I. persulcatus were clustered with F. tularensis type B strains distributed in Eurasia. Microinjected live F. tularensis persisted in ticks, whereas heat-killed F. tularensis decreased. Microinjected F. tularensis hlyD mutant decreased in ticks significantly compared to parent strain, thereby suggesting that HlyD in F. tularensis contributes to the adaptation or survive of bacterial infection in ticks. SIGNIFICANCE AND IMPACTS OF THE STUDY: Francisella tularensis has been detected in ticks, suggesting that it is a tick-borne pathogen. However, F. tularensis has not been detected in ticks in Japan since 1991. In this study, we performed a large-scale analysis of DNA isolated from ticks in Japan and detected F. tularensis by real-time polymerase chain reaction (PCR) and nested PCR. We found that F. tularensis could survive in ticks based on an experimental tick-infection model. We also identified a bacterial factor that contributes to survival in ticks. Our results suggest that ticks are candidate vectors that mediate F. tularensis infection in Japan.

Lower Respiratory Tract Adenoid Cystic Carcinoma: Its Management in the Past Decades.

AIMS: Adenoid cystic carcinoma of the lower respiratory tract is a rare indolent neoplasm with prolonged survival, propensity for recurrences and metastasis years after initial therapy. We aim to study a 1,700-bed single tertiary academic hospital's long-term experience with ACC of the lower respiratory tract from the larynx to the lungs and review published literature on this subject. MATERIALS AND METHODS: We analysed the clinicopathology, treatment options and outcome in 33 patients and reviewed the published literature over the last five decades. RESULTS: The tumour has no gender predilection, a peak incidence in the fifth decade and is not related to smoking. Insidious symptoms are often treated as benign obstructive airway disease and infection; negative signs and normal chest X-rays delayed diagnosis. The tumour was distributed most commonly in the trachea followed by main bronchi, lobar bronchi and larynx. About 22% of patients required emergent bronchoscopic intervention to secure airway patency before definitive therapy with surgery or/and radiotherapy. A high proportion of resected specimens had positive margins. Overall survival and disease-free survival rates at 5 years were 81 and 62%, respectively, and at 10 years 70 and 54%, respectively. Prolonged good palliation was achieved for patients with unresectable lesions with radiation and wide armamentarium of endoscopic therapy. CONCLUSIONS: In time, many patients eventually succumb to this disease. However, advances in medical skill and technology have prolonged survival while maintaining a good quality of life. Adenoid cystic carcinoma of the respiratory tract is a chronic life-long disease that may require interval intensive therapy. The challenge is to find the best therapeutic regimen aiming for a 'true' cure. Further study on the mutational landscape of adenoid cystic carcinoma may provide potential avenues for novel treatments to address a chemoresistant cancer.

Atomoxetine reverses locomotor hyperactivity, impaired novel object recognition, and prepulse inhibition impairment in mice lacking pituitary adenylate cyclase-activating polypeptide.

Attention-deficit/hyperactivity disorder (ADHD) is a complex neurobehavioral disorder that is characterized by attention difficulties, impulsivity, and hyperactivity. A non-stimulant drug, atomoxetine (ATX), which is a selective noradrenaline reuptake inhibitor, is widely used for ADHD because it exhibits fewer adverse effects compared to conventional psychostimulants. However, little is known about the therapeutic mechanisms of ATX. ATX treatment significantly alleviated hyperactivity of pituitary adenylate cyclase-activating polypeptide (PACAP)-deficient (PACAP(-/-)) mice with C57BL/6J and 129S6/SvEvTac hybrid background. ATX also improved impaired novel object recognition memory and prepulse inhibition in PACAP(-/-) mice with CD1 background. The ATX-induced increases in extracellular noradrenaline and dopamine levels were significantly higher in the prefrontal cortex of PACAP(-/-) mice compared to wild-type mice with C57BL/6J and 129S6/SvEvTac hybrid background. These results suggest that ATX treatment-induced increases in central monoamine metabolism may be involved in the rescue of ADHD-related abnormalities in PACAP(-/-) mice. Our current study suggests that PACAP(-/-) mice are an ideal rodent model with predictive validity for the study of ADHD etiology and drug development. Additionally, the potential effects of differences in genetic background of PACAP(-/-) mice on behaviors are discussed.

Peripheral circulation evaluation with near-infrared spectroscopy in skeletal muscle during cardiopulmonary bypass.

BACKGROUND: We designed a non-invasive, observational, real-time study, using near-infrared spectroscopy (NIRS) to assess the in vivo effects of cardiopulmonary bypass (CPB) on patients' skeletal muscle as well as the effects of hemodilution and hypothermia on tissue oxygen delivery during CPB. METHODS: The study included 20 consecutive adult patients undergoing open-heart surgery with CPB. Evaluation parameters for peripheral circulation were measured using the NIRO-200NX and recorded every 30 seconds. To assess how hemodilution influences peripheral circulation parameters, we compared data between a group of patients with hematocrit (Hct) values >22% (high Hct group) and those with Hct values ⩽22% (low Hct group). RESULTS: Changes in the concentration of oxygenated hemoglobin (ΔO2Hb, µmol/L), which flows into the skeletal muscle, was an important factor for deciding the tissue oxygenation index (TOI%), showing the tissue oxygen saturation. The low Hct group showed a significant increase in the normalized tissue hemoglobin index (nTHI), showing the percentage change in the amount of initial hemoglobin and TOI compared to the high Hct group. Changes in the concentration of oxygenated hemoglobin (ΔO2Hb, µmol/L) and deoxygenated hemoglobin (ΔHHb, µmol/L) were significantly less in the low Hct group than in the high Hct group, thus, showing good peripheral circulation despite the low hematocrit levels. CONCLUSION: Our study indicated the presence of a compensatory mechanism in which increased blood flow of the microcirculation is in compensation for the lack of oxyhemoglobin delivery caused by hemodilution.

Synthesis and biological evaluation of [¹¹C]AZ12504948; a novel tracer for imaging of glucokinase in pancreas and liver.

INTRODUCTION: Glucokinase (GK) is potentially a target for imaging of islets of Langerhans. Here we report the radiosynthesis and preclinical evaluation of the GK activator, [(11)C]AZ12504948, for in vivo imaging of GK. METHODS: [(11)C]AZ12504948 was synthesized by O-methylation of the precursor, AZ125555620, using carbon-11 methyl iodide ([(11)C]CH3I). Preclinical evaluation was performed by autoradiography (ARG) of human tissues and PET/CT studies in pig and non-human primate. RESULT: [(11)C]AZ12504948 was produced in reproducible good radiochemical yield in 28-30 min. Radiochemical purity of the formulated product was >98% for up to 2 h with specific radioactivities 855 ± 209 GBq/µmol (n=8). The preclinical evaluation showed some specificity for GK in liver, but not in pancreas. CONCLUSION: [(11)C]AZ12504948 images GK in liver, but the low specificity impedes the visualization of GK in pancreas. Improved target specificity is required for further progress using PET probes based on this class of GK activators.

A radiometabolite study of the serotonin transporter PET radioligand [(11)C]MADAM.

INTRODUCTION: (11)C]MADAM is a radioligand suitable for PET studies of the serotonin transporter (SERT). Metabolite analysis in human and non-human plasma samples using HPLC separation has shown that [(11)C]MADAM was rapidly metabolized. A possible metabolic pathway is the S-oxidation which could lead to SOMADAM and SO2MADAM. In vitro evaluation of these two potential metabolites has shown that SOMADAM exhibited a good affinity for SERT and a good selectivity for SERT over NET and DAT. METHODS: Comparative PET imaging studies in non-human primate brain with [(11)C]MADAM and [(11)C]SOMADAM were carried out, and plasma samples were analyzed using reverse phase HPLC. We have explored the metabolism of [(11)C]MADAM in rat brain with a view to understand its possible interference for brain imaging with PET. RESULTS: PET imaging studies in non-human primate brain using [(11)C]SOMADAM indicated that this tracer does not bind with high amounts to brain regions known to be rich in SERT. The fraction of [(11)C]SOMADAM in non-human primate plasma was approximately 5% at 4min and 1% at 15min after [(11)C]MADAM injection. HPLC analysis of brain sample after [(11)C]MADAM injection to rats demonstrated that [(11)C]SOMADAM was not detected in the brain. CONCLUSIONS: (11)C]SOMADAM is not superior over [(11)C]MADAM as a SERT PET radioligand. Nevertheless, [(11)C]SOMADAM has been identified as a minor labeled metabolite of [(11)C]MADAM measured in monkey plasma. [(11)C]SOMADAM was not detected in rat brain.

Suppressive effects of neutrophil by Salp16-like salivary gland proteins from Ixodes persulcatus†Schulze tick.

Salp16, a 16-kDa tick salivary gland protein, is known to be the molecule involved in the transmission of Anaplasma phagocytophilum, an obligate intracellular pathogen causing zoonotic anaplasmosis, from its mammalian hosts to Ixodes scapularis. Recently, the presence of A. phagocytophilum was documented in Japan and Ixodes persulcatus was identified as one of its vectors. The purpose of this study was to identify Salp16 genes in I. persulcatus and characterize their function. Two cDNA clones encoding the Salp16-like sequences were obtained from the salivary glands of fed female I. persulcatus ticks and designated Salp16 Iper1 and Iper2. Gene expression analyses showed that the Salp16 Iper genes were expressed specifically in the salivary glands and were up-regulated by blood feeding. These proteins attenuated the oxidative burst of activated bovine neutrophils and inhibited their migration induced by the chemoattractant interleukin-8 (IL-8). These results demonstrate that Salp16 Iper proteins contribute to the establishment of blood feeding as an immunosuppressant of neutrophil, an essential factor in innate host immunity. Further examination of the role of Salp16 Iper in the transmission of pathogens, including A. phagocytophilum, will increase our understanding of the tick-host-pathogen interface.

Accuracy evaluation of a two-wire technique for osteotomy positioning in the tibial plateau levelling procedure.

OBJECTIVE: To evaluate a tibial plateau levelling osteotomy (TPLO) saw blade positioning technique and to retrospectively evaluate the accuracy of the osteotomy position. METHOD: Preoperative and postoperative radiographs of 72 cases that had a TPLO surgery using a two-wire technique were reviewed. Three measurements (A1, B1, C1) were obtained in preoperative planning using a computer template system (Orthoview Vet) which mapped the intended osteotomy position. The postoperative radiographs were analysed to determine the variability of these three measurements (A2, B2, C2) and therefore the accuracy of the osteotomy. RESULTS: On average the least variable measurement was B2 (5%) followed by C2 (7%) and then A2 (13%). The maximum mean difference between the intended position and achieved position was 1.5 mm. CLINICAL SIGNIFICANCE: Despite there being a significant difference between the intended and the actual position of the osteotomy, the variation between the intended and actual tibial tuberosity width was small (5%). None of the cases suffered a tibial tuberosity fracture, which also supports the clinical value of this technique. Care must be taken to avoid inadvertent cutting of the Kirschner guide wires.

A comprehensive pathological survey of duodenal biopsies from dogs with diet-responsive chronic enteropathy.

BACKGROUND: The detailed pathological phenotype of diet-responsive chronic enteropathy (CE) and its modulation with dietary therapy remain poorly characterized. HYPOTHESIS/OBJECTIVES: Key mucosal lesions of diet-responsive CE resolve with dietary therapy. METHODS: This was a prospective observational study of 20 dogs with diet-responsive CE. Endoscopic duodenal biopsies collected before and 6 weeks after the start of a dietary trial were assessed by means of qualitative and quantitative histopathological, immunohistochemical, and ultrastructural criteria. Control duodenal biopsies were obtained from 10 healthy Beagle dogs on 1 occasion. RESULTS: Compared with control dogs, the CE dogs had higher villus stunting scores and higher overall WSAVA scores, a lower villus height-to-width ratio, and higher lamina propria density of eosinophils. The CE dogs also had ultrastructural lesions of the mitochondria and brush border. In common with other studies in which the disease and control populations are not matched for breed, age, sex, and environment, these comparisons should be interpreted with caution. Comparing biopsies collected at presentation and 6 weeks after starting the dietary trial, mean lamina propria mononuclear cell score and lamina propria densities of eosinophils and mononuclear cells decreased. Dietary therapy also improved ultrastructural lesions of the mitochondria and brush border, eliciting a decrease in intermicrovillar space and an increase in microvillus height. CONCLUSIONS AND CLINICAL IMPORTANCE: In dogs with diet-responsive CE, the remission of clinical signs with dietary therapy is associated with subtle decreases in lamina propria density of eosinophils and mononuclear cells, and resolution of ultrastructural lesions of the enterocyte.

A systematic approach to the development of novel therapeutics for lung cancer using genomic analyses.

Molecularly targeted drugs for cancer therapy represent a therapeutic advance, but the proportion of patients who receive clinical benefit is still very limited. We present here the rationale and initial results of our program to define molecules involved in lung carcinogenesis with the goal of identifying new therapeutic targets and/or predictive biomarkers for drug response. We have used gene expression analysis of 120 lung cancers followed by RNA interference, tumor-tissue microarray analysis, and functional analyses to systematically distinguish potential target molecules specifically expressed in cancer cells. Through this approach, we have identified oncoproteins that provide the starting point for the development of therapeutic antibodies, dominant negative peptides, small-molecule inhibitors, and therapeutic cancer vaccines. We believe that the approach we describe should result in new molecularly targeted therapies with minimal risk of adverse events.

Two novel Salp15-like immunosuppressant genes from salivary glands of Ixodes persulcatus Schulze tick.

Salp15, a 15-kDa tick salivary gland protein, is known for several suppressive activities against host immunity and critical functions for the transmission of Lyme borrelia in Ixodes scapularis and Ixodes ricinus, the major vectors found in North America and Western Europe. Salp15 inhibits the activation of cluster of differentiation (CD)4(+)T-cells through the repression of T-cell receptor (TCR)-triggered calcium fluxes and interleukin (IL)-2 production. Furthermore, Salp15 adheres to the spirochaeta and specifically interacts with its outer surface protein C. The binding of Salp15 to Borrelia burgdorferi protects it from antibody-mediated killing in vitro. The aim of this study is to identify the Salp15 genes in Ixodes persulcatus Schulze, the specific vector for human Lyme borreliosis in Japan. Two cDNA clones encoding the Salp15-like sequence were obtained from salivary glands of fed female ticks. These genes encode 135- and 132-amino acid proteins, designated Salp15 Iper-1 and Salp15 Iper-2, respectively, both having signal peptide sequences and predicted to be secretory proteins. Salp15 Iper-1 and -2 showed 51.8 and 68.2% similarity to I. scapularis Salp15, respectively. Reverse transcriptase PCR analysis showed that Salp15 Iper genes were expressed specifically in the salivary glands throughout life cycle stages of the ticks and were up-regulated by blood feeding. In the I. persulcatus-derived sequences, the C-terminal part, which is the binding domain to the CD4 molecule of T-cells in I. scapularis Salp15, was well conserved. In the future, it will be necessary to analyse immunosuppressive functions of I. persulcatus Salp15 and their interaction with Borrelia spp. in Japan.

Screening of Nepalese crude drugs traditionally used to treat hyperpigmentation: in vitro tyrosinase inhibition.

South-East Asian population is daily exposed to strong sunlight. As a result, the majority of population will have darker, ethnic skin. Moreover, many people suffer from dark spots, hyperpigmentation, which is considered to be a skin disorder and causes psychological disturbance. To treat dark spots, most of the population will still rely on traditionally used crude drugs, knowledge about which is transferred from generation to generation. Fifty-two crude drugs were selected based on the survey performed among local healers and beauticians of different ethnic origin. These crude drugs were screened for mushroom tyrosinase inhibitory activity, as tyrosinase inhibitors are becoming increasingly important as cosmetic and medicinal products, primarily to control hyperpigmentation. Among the tested crude drugs, methanolic extracts of Glycyrrhiza glabra, Morus alba, Syzygium aromaticum, Citrus aurantifolia, Cypreae moneta, Punica granatum and Citrus aurantium, at the final concentration of 50 microg mL(-1), showed mushroom tyrosinase inhibitory activity of 78.9%, 71.0%, 69.4%, 59.0%, 56.0%, 53.4 and 51.9%, respectively, with 91.4% inhibitory activity of kojic acid taken as positive control. To our knowledge, this is the first report that extracts of Cypreae moneta shell and Syzygium aromaticum flowering bud have tyrosinase inhibitory activity. These potent extracts were further evaluated at different concentration. The final concentration of the extracts in reaction mixtures was 50, 25 and 5 microg mL(-1) for the initial concentration of 1000, 500 and 100 microg mL(-1), respectively. They showed concentration-dependent inhibition of mushroom tyrosinase. Those extracts expressing relatively weak tyrosinase inhibitory activity may act through different inhibition pathway which is not based on tyrosinase activity. Further evaluation of the most potent tyrosinase inhibitors in in vivo conditions would be recommended.

Genomic organization and promoter analysis of the bovine ADAM12 gene.

A disintegrin and metalloprotease (ADAM) 12 is a member of the ADAM family possessing a putative role in a variety of biological processes such as modulation of proteolytic processing, cell adhesion, cell fusion, and signaling. Recently, it has been suggested that ADAM12 is involved in regulation of adipogenesis as well as myogenesis. In this study, we have determined the genomic structure of 5'- and 3'-regions in the bovine ADAM12 gene. We could obtain characteristics of lower homology of its exon 2 with human counterpart. Human exon S19 encodes for the sequence specific to a shorter secreted form of ADAM12S. The bovine ADAM12 gene had no canonical 3'-splice acceptor site at 5'-side of the putative exon S19, suggesting that the cattle could not produce a ADAM12S counterpart. To identify the regulatory elements, a 12 kb 5'-flanking region of the gene was cloned and luciferase reporter assay was carried out. Reporter plasmids with different length of proximal promoter region indicated the similar patterns of promoter activities between 3T3-L1 preadipose and Cos-1 nonadipose cells. However, 2.0 and 0.2 kb fragments located at - 8 and - 4.5 kb upstream of the putative transcription start site, respectively, increased the ADAM12 promoter activity about 1.5- to 2-fold in 3T3-L1, but not in Cos-1. These results suggested that the two distal regions might contribute to the preadipocyte-specific expression of ADAM12 gene.

Linkage disequilibrium structures in cattle and their application to breed identification testing.

We examined the extent of linkage disequilibrium (LD) block lengths in four breed populations: Japanese Black, Angus, Hereford and Holstein. Three chromosomal regions in which QTL were previously mapped in Japanese Black populations were scanned with 84 microsatellite markers. The estimated LD lengths in these four purebred populations varied from 535 to 683 kb, which is much shorter than the values reported previously. Our findings suggest that QTL can be mapped in sub-centimorgan regions in these populations using an LD-mapping method. We also developed breed identification methods to distinguish Japanese Black from Angus, Hereford, Holstein and F(1) animals (Japanese Black x Holstein) respectively using the haplotypic frequencies of a pair of markers in the breed populations. After assessing the distributions of posterior probabilities to be Japanese Black, we obtained several pairs of markers that completely distinguished Japanese Black from the other breeds. We also obtained several combinations of six markers that completely distinguished Japanese Black animals from F(1) animals.

Trans-Tenon's retrobulbar triamcinolone acetonide injection for macular oedema related to branch retinal vein occlusion.

BACKGROUND: The aim of the study was to evaluate the safety and effectiveness of trans-Tenon's retrobulbar triamcinolone acetonide (TA) injection for macular oedema associated with branch retinal vein occlusion (BRVO). METHODS: We reviewed the medical records of 50 consecutive patients with macular oedema associated with BRVO who were treated with trans-Tenon's retrobulbar TA injection (20 mg) as initial treatment for a follow-up period of at least 12 months. Foveal thickness determined by optical coherence tomography, visual acuity, intraocular pressure (IOP) and cataract progression were measured. RESULTS: The mean duration between oedema onset and TA injection was 4.9 months. Foveal thickness decreased significantly at 3 months after injection (p<0.0001). Furthermore, the percentage reduction in foveal thickness in eyes with posterior vitreous detachment (PVD; n = 23) was significantly greater than that without PVD (n = 27, p = 0.003). Improved visual acuity by at least 0.20 log minimum angle of resolution (logMAR) was seen in 22 eyes (44%; 11 eyes with PVD and 11 eyes without PVD). After completion of the 3-month follow-up, 29 eyes (58%) needed additional treatment including TA injections or pars plana vitrectomy (PPV). PPV seemed to be effective for macular oedema resistant to TA. IOP elevation and cataract progression occurred in less than 10% of all patients. CONCLUSIONS: Trans-Tenon's retrobulbar TA injection appeared safe and relatively effective for macular oedema associated with BRVO. In eyes resistant to TA injection, PPV may be effective as an adjunctive treatment.

Chain elongation suppression of cyclic block copolymers in lamellar microphase-separated bulk.

Chain elongation suppression of cyclic block copolymers in microphase-separated bulk was determined quantitatively. Solvent-cast and annealed films are confirmed to show alternating lamellar structure and their microdomain spacing D increases with increasing total molecular weight M according to the relationship D proportional, variant M0.59, which agrees quite consistently with the theoretically predicted power law, i.e., D proportional, variant M3/5. This result is in contrast to the well-established issue for linear block copolymers, where the relationship D proportional, variant M2/3 has been confirmed to hold both experimentally and theoretically. This means that chain elongation of each component block is suppressed considerably, owing to their looped conformation in strongly segregated bulk.

Two cell-counting factors regulate the aggregate size of the cellular slime mold Dictyostelium discoideum.

Countin, a cell-counting factor in Dictyostelium discoideum, is considered to limit the maximum size of the multicellular structure, because a countin null strain forms a huge fruiting body compared to that of the wild-type. A novel gene, countin2, that is highly homologous to countin (40% identity in amino acid sequence) was identified in the D. discoideum genome. The countin2 null strain formed a 1.7-fold higher number of the aggregates, resulting in smaller fruiting bodies compared with those of wild-type cells. Thus, the Countin2 protein is thought to limit the minimum size of the multicellular structure. The size and number of aggregates formed by a mixture of countin null and countin2 null strains were the same as those of the wild-type. These findings demonstrate that a combination of Countin and Countin2 proteins determines the appropriate size of the multicellular structure of D. discoideum.