Assessment of mitral annulus velocity by Doppler tissue imaging in the evaluation of left ventricular diastolic function

OBJECTIVES

This study assessed the clinical utility of mitral annulus velocity in the evaluation of left ventricular diastolic function.

BACKGROUND

Mitral inflow velocity recorded by Doppler echocardiography has been widely used to evaluate left ventricular diastolic function but is affected by other factors. The mitral annulus velocity profile during diastole may provide additional information about left ventricular diastolic function.

METHODS

Mitral annulus velocity during diastole was measured by Doppler tissue imaging (DTI) 1) in 59 normal volunteers (group 1); 2) in 20 patients with a relaxation abnormality as assessed by Doppler mitral inflow variables (group 2) at baseline and after saline loading; 3) in 11 patients (group 3) with normal diastolic function before and after intravenous nitroglycerin infusion; and 4) in 38 consecutive patients (group 4) undergoing cardiac catheterization in whom mitral inflow velocity and tau as well as mitral annulus velocity were measured simultaneously.

RESULTS

In group 1, mean +/- SD peak early and late diastolic mitral annulus velocity was 10.0 +/- 1.3 and 9.5 +/- 1.5 cm/s, respectively. In group 2, mitral inflow velocity profile changed toward the pseudonormalization pattern with saline loading (deceleration time 311 +/- 84 ms before to 216 +/- 40 ms after intervention, p < 0.001), whereas peak early diastolic mitral annulus velocity did not change significantly (5.3 +/- 1.2 cm/s to 5.7 +/- 1.4 cm/s, p = NS). In group 3, despite a significant change in mitral inflow velocity profile after nitroglycerin, peak early diastolic mitral annulus velocity did not change significantly (9.5 +/- 2.2 cm/s to 9.2 +/- 1.7 cm/s, p = NS). In group 4, peak early diastolic mitral annulus velocity (r = -0.56, p < 0.01) and the early/late ratio (r = -0.46, p < 0.01) correlated with tau. When the combination of normal mitral inflow variables with prolonged tau (> or = 50 ms) was classified as pseudonormalization, peak early diastolic mitral annulus velocity < 8.5 cm/s and the early/late ratio < 1 could identify the pseudonormalization with a sensitivity of 88% and specificity of 67%.

CONCLUSIONS

Mitral annulus velocity determined by DTI is a relatively preload-independent variable in evaluating diastolic function.

Activated STING in a vascular and pulmonary syndrome

BACKGROUND

The study of autoinflammatory diseases has uncovered mechanisms underlying cytokine dysregulation and inflammation.

METHODS

We analyzed the DNA of an index patient with early-onset systemic inflammation, cutaneous vasculopathy, and pulmonary inflammation. We sequenced a candidate gene, TMEM173, encoding the stimulator of interferon genes (STING), in this patient and in five unrelated children with similar clinical phenotypes. Four children were evaluated clinically and immunologically. With the STING ligand cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), we stimulated peripheral-blood mononuclear cells and fibroblasts from patients and controls, as well as commercially obtained endothelial cells, and then assayed transcription of IFNB1, the gene encoding interferon-β, in the stimulated cells. We analyzed IFNB1 reporter levels in HEK293T cells cotransfected with mutant or nonmutant STING constructs. Mutant STING leads to increased phosphorylation of signal transducer and activator of transcription 1 (STAT1), so we tested the effect of Janus kinase (JAK) inhibitors on STAT1 phosphorylation in lymphocytes from the affected children and controls.

RESULTS

We identified three mutations in exon 5 of TMEM173 in the six patients. Elevated transcription of IFNB1 and other gene targets of STING in peripheral-blood mononuclear cells from the patients indicated constitutive activation of the pathway that cannot be further up-regulated with stimulation. On stimulation with cGAMP, fibroblasts from the patients showed increased transcription of IFNB1 but not of the genes encoding interleukin-1 (IL1), interleukin-6 (IL6), or tumor necrosis factor (TNF). HEK293T cells transfected with mutant constructs show elevated IFNB1 reporter levels. STING is expressed in endothelial cells, and exposure of these cells to cGAMP resulted in endothelial activation and apoptosis. Constitutive up-regulation of phosphorylated STAT1 in patients' lymphocytes was reduced by JAK inhibitors.

CONCLUSIONS

STING-associated vasculopathy with onset in infancy (SAVI) is an autoinflammatory disease caused by gain-of-function mutations in TMEM173. (Funded by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases; ClinicalTrials.gov number, NCT00059748.).

Tumor microsatellite instability and clinical outcome in young patients with colorectal cancer

BACKGROUND

Colorectal cancer can arise through two distinct mutational pathways: microsatellite instability or chromosomal instability. We tested the hypothesis that colorectal cancers arising from the microsatellite-instability pathway have distinctive clinical attributes that affect clinical outcome.

METHODS

We tested specimens of colorectal cancer from a population-based series of 607 patients (50 years of age or younger at diagnosis) for microsatellite instability. We compared the clinical features and survival of patients who had colorectal cancer characterized by high-frequency microsatellite instability with these characteristics in patients who had colorectal cancers with microsatellite stability.

RESULT

We found high-frequency microsatellite instability in 17 percent of the colorectal cancers in 607 patients, and in a multivariate analysis, microsatellite instability was associated with a significant survival advantage independently of all standard prognostic factors, including tumor stage (hazard ratio, 0.42; 95 percent confidence interval, 0.27 to 0.67; P< 0.001). Furthermore, regardless of the depth of tumor invasion, colorectal cancers with high-frequency microsatellite instability had a decreased likelihood of metastasizing to regional lymph nodes (odds ratio, 0.33; 95 percent confidence interval, 0.21 to 0.53; P< 0.001) or distant organs (odds ratio, 0.49; 95 percent confidence interval, 0.27 to 0.89; P=0.02).

CONCLUSION

High-frequency microsatellite instability in colorectal cancer is independently predictive of a relatively favorable outcome and, in addition, reduces the likelihood of metastases.

Dye efflux studies suggest that hematopoietic stem cells expressing low or undetectable levels of CD34 antigen exist in multiple species

We previously described a method for isolating murine hematopoietic stem cells capable of reconstituting lethally irradiated recipients, which depends solely on dual-wavelength flow cytometric analysis of murine bone marrow cells stained with the fluorescent DNA-binding dye Hoechst 33342. This method, which appears to rely on the differential ability of stem cells to efflux the Hoechst dye, defines an extremely small and homogeneous population of cells (termed SP cells). We show here that dual-wavelength analysis of Hoechst dye-stained human, rhesus and miniature swine bone marrow cells reveals a small, distinct population of cells that efflux the dye in a manner identical to murine SP cells. Like the murine SP cells, both human and rhesus SP cells are primarily CD34-negative and lineage marker-negative. In vitro culture studies demonstrated that rhesus SP cells are highly enriched for long-term culture-initiating cells (LTC-ICs), an indicator of primitive hematopoietic cells, and have the capacity for differentiation into T cells. Although rhesus SP cells do not initially possess any hematopoietic colony-forming capability, they acquire the ability to form colonies after long-term culture on bone marrow stroma, coincident with their conversion to a CD34-positive phenotype. These studies suggest the existence of a hitherto unrecognized population of hematopoietic stem cells that lack the CD34 surface marker classically associated with primitive hematopoietic cells.

Crystal structure of the cytochrome bc1 complex from bovine heart mitochondria

On the basis of x-ray diffraction data to a resolution of 2.9 angstroms, atomic models of most protein components of the bovine cytochrome bc1 complex were built, including core 1, core 2, cytochrome b, subunit 6, subunit 7, a carboxyl-terminal fragment of cytochrome c1, and an amino-terminal fragment of the iron-sulfur protein. The positions of the four iron centers within the bc1 complex and the binding sites of the two specific respiratory inhibitors antimycin A and myxothiazol were identified. The membrane-spanning region of each bc1 complex monomer consists of 13 transmembrane helices, eight of which belong to cytochrome b. Closely interacting monomers are arranged as symmetric dimers and form cavities through which the inhibitor binding pockets can be accessed. The proteins core 1 and core 2 are structurally similar to each other and consist of two domains of roughly equal size and identical folding topology.

Histochemical and ultrastructural demonstration of gamma-glutamyl transpeptidase activity

A simultaneous coupling azo dye method for the histochemical demonstration of γ-glutamyl transpeptidase activity using the new substrate γ-glutamyl-4-methoxy-2-naphthylamide has been described. The method appears superior to previously reported methods for γ-glutamyl transpeptidase activity and can easily be modified for the electron microscopic localization of the enzyme by bridging osmium to the copper chelate of the azo dye via thiocarbohydrazide. The optimum conditions for the histochemical reaction were developed and the distribution of enzymatic activity in the tissues of the rat is described for light microscopy and with rat pancreas for electron microscopy. The electron-opaque deposits were seen in the endoplasmic reticulum in the vicinity of the zymogen granules in the apical portion of the acinar cell.

MADR2 maps to 18q21 and encodes a TGFbeta-regulated MAD-related protein that is functionally mutated in colorectal carcinoma

The MAD-related (MADR) family of proteins are essential components in the signaling pathways of serine/threonine kinase receptors for the transforming growth factor beta (TGFbeta) superfamily. We demonstrate that MADR2 is specifically regulated by TGFbeta and not bone morphogenetic proteins. The gene for MADR2 was found to reside on chromosome 18q21, near DPC4, another MADR protein implicated in pancreatic cancer. Mutational analysis of MADR2 in sporadic tumors identified four missense mutations in colorectal carcinomas, two of which display a loss of heterozygosity. Biochemical and functional analysis of three of these demonstrates that the mutations are inactivating. These findings suggest that MADR2 is a tumor suppressor and that mutations acquired in colorectal carcinomas may function to disrupt TGFbeta signaling.

The full-length leptin receptor has signaling capabilities of interleukin 6-type cytokine receptors

The leptin receptor (OB-R) is a single membrane-spanning protein that mediates the weight regulatory effects of leptin (OB protein). The mutant allele (db) of the OB-R gene encodes a protein with a truncated cytoplasmic domain that is predicted to be functionally inactive. Several mRNA splice variants encoding OB-Rs with different length cytoplasmic domains have been detected in various tissues. Here we demonstrate that the full-length OB-R (predominantly expressed in the hypothalamus), but not a major naturally occurring truncated form or a mutant from found in db/db mice, can mediate activation of signal transducer and activator of transcription (STAT) proteins and stimulate transcription through interleukin 6 responsive gene elements. Reconstitution experiments suggest that, although OB-R mediates intracellular signals with a specificity similar to interleukin 6-type cytokine receptors, signaling appears to be independent of the gp130 signal transducing component of the interleukin 6-type cytokine receptors.

Phylogenetic affiliation of the pseudomonads based on 16S rRNA sequence

The broad and vague phenotypic definition allowed the genus Pseudomonas to become a dumping ground for incompletely characterized polarly flagellated, gram-negative, rod-shaped, aerobic bacteria, and a large number of species have been accommodated in the genus Pseudomonas. The 16S rRNA sequences of 128 valid and invalid Pseudomonas species, which included almost valid species of the genus Pseudomonas listed in the Approved Lists of Bacterial Names, were obtained: sequences of 59 species were determined and those of 69 species were obtained from the GenBank/EMBL/DDBJ databases. These sequences were compared with the sequences of other species of the Proteobacteria. Fifty-seven valid or invalid species including Pseudomonas aeruginosa (type species of the genus Pseudomonas Migula 1894) belonged to the genus Pseudomonas (sensu stricto). Seven subclusters were formed in the cluster of the genus Pseudomonas (sensu stricto), and the resulting clusters conformed well to the rRNA-DNA hybridization study by Palleroni (1984). The other species did not belong to the genus Pseudomonas (sensu stricto) and were related to other genera, which were placed in four subclasses of the Proteobacteria (alpha, beta, gamma and gamma-beta subclasses). Twenty-six examined species, which were not included in the cluster of the Pseudomonas (sensu stricto) and have not been transferred to other genera as yet, are listed alphabetically: 'Pseudomonas abikonensis', Pseudomonas antimicrobica, Pseudomonas beijerinckii, Pseudomonas beteli, Pseudomonas boreopolis, 'Pseudomonas butanovora', Pseudomonas carboxydohydrogena, Pseudomonas cissicola, Pseudomonas doudoroffii, Pseudomonas echinoides, Pseudomonas elongata, Pseudomonas flectens, Pseudomonas geniculata, Pseudomonas halophila, Pseudomonas hibiscicola, Pseudomonas huttiensis, Pseudomonas iners, Pseudomonas lanceolata, Pseudomonas lemoignei, Pseudomonas mephitica, Pseudomonas pictorum, Pseudomonas saccharophila, Pseudomonas spinosa, Pseudomonas stanier, Pseudomonas syzygii and Pseudomonas woodsii. The phylogenetic affiliations of these 26 pseudomonads species are shown.

Allelic loss of chromosome 18q and prognosis in colorectal cancer

BACKGROUND

Colorectal cancer occurs in approximately 150,000 people each year in the United States. Prognostic assessment influences the treatment of patients with colorectal cancer, including decisions about adjuvant therapy. We evaluated chromosome 18q allelic loss, a genetic event associated with tumor progression, as a prognostic marker for this disease.

METHODS

We developed procedures to examine the status of chromosome 18q with microsatellite markers and DNA from formalin-fixed, paraffin-embedded tumors. Allelic loss of chromosome 18q was assessed in 145 consecutively resected stage II or III colorectal carcinomas.

RESULTS

Among patients with stage II disease, the five-year survival rate was 93 percent in those whose tumor had no evidence of allelic loss of chromosome 18q and 54 percent in those with allelic loss; among patients with stage III disease, survival was 52 and 38 percent, respectively. The overall estimated hazard ratio for death in patients whose tumor had chromosome 18q allelic loss was 2.83 (P = 0.008) according to univariate analysis. Furthermore, chromosome 18q allelic loss remained a strong predictive factor (hazard ratio for death, 2.46; 95 percent confidence interval, 1.06 to 5.71; P = 0.036) after adjustment for all other evaluated factors, including tumor differentiation, vein invasion, and TNM stage.

CONCLUSIONS

The status of chromosome 18q has strong prognostic value in patients with stage II colorectal cancer. The prognosis in patients with stage II cancer and chromosome 18q allelic loss is similar to that in patients with stage III cancer, who are thought to benefit from adjuvant therapy. In contrast, patients with stage II disease who do not have chromosome 18q allelic loss in their tumor have a survival rate similar to that of patients with stage I disease and may not require additional therapy.

The periodic association of MAP2 with brain microtubules in vitro

Several high molecular weight polypeptides have been shown to quantitatively copurify with brain tubulin during cycles of in vitro assembly-disassembly. These microtubule-associated proteins (MAPs) have been shown to influence the rate and extent of microtubule assembly in vitro. We report here that a heat-stable fraction highly enriched for one of the MAPs, MAP2 (mol wt approximately 300,000 daltons), devoid of MAP1 (mol wt approximately 350,000 daltons), has been purified from calf neurotubules. This MAP2 fraction stoichiometrically promotes microtubule assembly, lowering the critical concentration for tubulin assembly to 0.05 mg/ml. Microtubules saturated with MAP2 contain MAP2 and tubulin in a molar ratio of approximately 1 mole of MAP2 to 9 moles of tubulin dimer. Electron microscopy of thin sections of the MAP2-saturated microtubules fixed in the presence of tannic acid demonstrates a striking axial periodicity of 32 +/- 8 nm.

The landscape and therapeutic relevance of cancer-associated transcript fusions

Transcript fusions as a result of chromosomal rearrangements have been a focus of attention in cancer as they provide attractive therapeutic targets. To identify novel fusion transcripts with the potential to be exploited therapeutically, we analyzed RNA sequencing, DNA copy number and gene mutation data from 4,366 primary tumor samples. To avoid false positives, we implemented stringent quality criteria that included filtering of fusions detected in RNAseq data from 364 normal tissue samples. Our analysis identified 7,887 high confidence fusion transcripts across 13 tumor types. Our fusion prediction was validated by evidence of a genomic rearrangement for 78 of 79 fusions in 48 glioma samples where whole genome sequencing data was available. Cancers with higher levels of genomic instability showed a corresponding increase in fusion transcript frequency, whereas tumor samples harboring fusions contained statistically significantly fewer driver gene mutations, suggesting an important role for tumorigenesis. We identified at least one in-frame protein kinase fusion in 324 of 4,366 samples (7.4%). Potentially druggable kinase fusions involving ALK, ROS, RET, NTRK, and FGFR gene families were detected in bladder carcinoma (3.3%), glioblastoma (4.4%), head and neck cancer (1.0%), low grade glioma (1.5%), lung adenocarcinoma (1.6%), lung squamous cell carcinoma (2.3%), and thyroid carcinoma (8.7%), suggesting a potential for application of kinase inhibitors across tumor types. In-frame fusion transcripts involving histone methyltransferase or histone demethylase genes were detected in 111 samples (2.5%) and may additionally be considered as therapeutic targets. In summary, we described the landscape of transcript fusions detected across a large number of tumor samples and revealed fusion events with clinical relevance that have not been previously recognized. Our results support the concept of basket clinical trials where patients are matched with experimental therapies based on their genomic profile rather than the tissue where the tumor originated.

Malignant lymphoma, lymphoblastic

Among the malignant lymphomas of the diffuse, poorly differentiated lymphocytic type, a cytologically distinctive form can be recognized. It is composed of immature lymphoid cells that are indistinguishable from the cells of acute lymphoblastic leukemia (ALL). Although these neoplasms usually have been classified as malignant lymphoma, lymphoblastic type, they contain, in addition to lymphoblasts, prolymphocytes in varying proportions. On the basis of the nuclear morphology, malignant lymphoma of the lymphoblastic type, (MLLB) can be further divided into those with and those without convoluted nuclei. In our series both groups had the following clinical features in common: 1) frequent occurrence in children and adolescents; 2) clinical presentation with mediastinal masses in 50% of cases; 3) a high incidence of bone marrow and perpheral blood involvement during the course of the disease; and 4) rapid progression of the disease with a median survival of 8 months. Our observations indicate that nuclear convolutions are helpful but not essential for the recognition of a clinicopathologic entity which is histologically and cytologically characterized by 1) the immaturity of the lymphoid cells indistinguishable from the lymphoblasts and prolymphocytes of ALL and 2) a high mitotic index. Because of the frequency with which MLLB progresses into ALL, systemic therapy may be indicated even before this progression is hematologically evident. This indicates the need for morphologic recognition of this malignant lymphoma regardless of the presence of nuclear convolution, age of the patient, and site of presentation.

Nasal obstruction as a risk factor for sleep-disordered breathing. The University of Wisconsin Sleep and Respiratory Research Group

Nasal obstruction frequently has been associated with sleep-disordered breathing as a potential etiologic factor. Nasal obstruction results in pathologic changes in airflow velocity and resistance. Experimentally produced nasal obstruction increases resistance and leads to sleep-disordered breathing events, including apnea, hypopnea, and snoring. Clinical research examining the correlation between nasal obstruction and sleep-disordered breathing is limited, especially in regard to patients with conditions that increase nasal resistance, such as rhinitis and sinusitis. To further identify risk factors for sleep-disordered breathing, the role of chronic and acute nasal congestion was investigated in a population-based sample. Data on nasal congestion history and sleep problems were obtained by questionnaire (n = 4927) and by objective inlaboratory measurement (n = 911). Participants who often or almost always experienced nighttime symptoms of rhinitis (5 or more nights a month) were significantly (p < 0.0001) more likely to report habitual snoring (3 to 7 nights a week), chronic excessive daytime sleepiness, or chronic nonrestorative sleep than were those who rarely or never had symptoms. Habitual snorers had significantly (p < 0.02) lower air flow than nonsnorers, although a linear relation between decreased airflow and sleep-disordered breathing severity did not exist. Participants who reported nasal congestion due to allergy were 1.8 times more likely to have moderate to severe sleep-disordered breathing than were those without nasal congestion due to allergy. Men and women with nasal obstruction, especially chronic nighttime symptoms of rhinitis, are significantly more likely to be habitual snorers, and a proportion also may have frequent episodes of apnea and hypopnea, indicative of severe sleep-disordered breathing. Because allergic rhinitis is a common cause of nasal obstruction and it is a modifiable risk factor, further study of this association is warranted.

Prevention of pulmonary morbidity for patients with Duchenne muscular dystrophy

STUDY OBJECTIVE

To evaluate the effects of a new respiratory management protocol on respiratory morbidity and hospitalization rates for patients with Duchenne muscular dystrophy (DMD).

DESIGN

A retrospective cohort study.

METHODS

Using a protocol in which oxyhemoglobin desaturation was prevented or reversed by the use of noninvasive intermittent positive pressure ventilation (IPPV) and assisted coughing as needed, the hospitalization rates and days for 24 protocol DMD ventilator users were compared with those of 22 nonprotocol DMD tracheostomy IPPV users.

RESULTS

The 22 conventionally managed patients were hospitalized a mean of 72.2+/-112 days when undergoing tracheostomy. This included a 16.1+/-5.4-day period of translaryngeal intubation. The 24 protocol patients were hospitalized a mean of 6.0+/-2.4 days (p<0.005) when beginning ventilator use. Over their next 126.2 patient-years of ventilator use, the 24 protocol patients had significantly lower rates of hospitalization (p<0.008) and hospitalization days (p<0.005) than had the tracheostomy IPPV users over a 167.2 patient-year period. This is true although 14 of the 24 protocol patients went on to require 24-h noninvasive IPPV for 4.5+/-3.6 years. Five of the 14 have yet to be hospitalized.

CONCLUSION

The use of inspiratory and expiratory aids can prolong survival while significantly decreasing the pulmonary morbidity and hospitalization rates associated with conventional resort to tracheostomy IPPV.

Malignant histiocytosis (histiocytic medullary reticulosis). I. Clinicopatholigic study of 29 cases

The clinical records and histologic material from 29 cases of malignant histiocytosis (MH) have been reviewed, as well as autopsy findings in 14 cases. The mean age was 31 years, with a 2.2:1 male to female preponderance. Major physical findings included temperature elevation, lymphadenopathy, hepatomegaly, splenomegaly, and preterminal jaundice. Common laboratory findings were anemia, leukopenia, and thrombocytopenia. The median survival was 6 months, the mean 14 months, and the range from 1 month to 8 years. The histologic features observed in lymph nodes, liver, spleen, and bone marrow have been emphasized, as well as features useful in differential diagnosis. In contrast to our experience with the non-Hodgkin's lymphomas, bone marrow aspiration was superior to biopsy in assessing marrow involvement. Unusual manifestations included soft tissue infiltration in 5 cases; 2 of these patients presented with a soft tissue mass. The distinctive clinical as well as histologic findings warrant recognition and separation of MH from other hematopoietic disorders.

A functional bone morphogenetic protein system in the ovary

Bone morphogenetic proteins (BMPs) comprise a large group of polypeptides in the transforming growth factor beta superfamily with essential physiological functions in morphogenesis and organogenesis in both vertebrates and invertebrates. At present, the role of BMPs in the reproductive system of any species is poorly understood. Here, we have established the existence of a functional BMP system in the ovary, replete with ligand, receptor, and novel cellular functions. In situ hybridization histochemistry identified strong mRNA labeling for BMP-4 and -7 in the theca cells and BMP receptor types IA, IB, and II in the granulosa cells and oocytes of most follicles in ovaries of normal cycling rats. To explore the paracrine function of this BMP system, we examined the effects of recombinant BMP-4 and -7 on FSH (follicle-stimulating hormone)-induced rat granulosa cytodifferentiation in serum-free medium. Both BMP-4 and -7 regulated FSH action in positive and negative ways. Specifically, physiological concentrations of the BMPs enhanced and attenuated the stimulatory action of FSH on estradiol and progesterone production, respectively. These effects were dose- and time-dependent. Furthermore, the BMPs increased granulosa cell sensitivity to FSH. Thus, BMPs have now been identified as molecules that differentially regulate FSH-dependent estradiol and progesterone production in a way that reflects steroidogenesis during the normal estrous cycle. As such, it can be hypothesized that BMPs might be the long-sought "luteinization inhibitor" in Graafian follicles during their growth and development.

Twisted gastrulation is a conserved extracellular BMP antagonist

Bone morphogenetic protein (BMP) signalling regulates embryonic dorsal-ventral cell fate decisions in flies, frogs and fish. BMP activity is controlled by several secreted factors including the antagonists chordin and short gastrulation (SOG). Here we show that a second secreted protein, Twisted gastrulation (Tsg), enhances the antagonistic activity of Sog/chordin. In Drosophila, visualization of BMP signalling using anti-phospho-Smad staining shows that the tsg and sog loss-of-function phenotypes are very similar. In S2 cells and imaginal discs, TSG and SOG together make a more effective inhibitor of BMP signalling than either of them alone. Blocking Tsg function in zebrafish with morpholino oligonucleotides causes ventralization similar to that produced by chordin mutants. Co-injection of sub-inhibitory levels of morpholines directed against both Tsg and chordin synergistically enhances the penetrance of the ventralized phenotype. We show that Tsgs from different species are functionally equivalent, and conclude that Tsg is a conserved protein that functions with SOG/chordin to antagonize BMP signalling.

Mechanisms of action of the soy isoflavone genistein: emerging role for its effects via transforming growth factor beta signaling pathways

The soy isoflavone genistein attenuates growth factor- and cytokine-stimulated proliferation of both normal and cancer cells. This article reviews our current understanding of the potential mechanisms of action of genistein. In membrane preparations from mammalian cells, genistein is a potent and specific inhibitor of tyrosine autophosphorylation of the epidermal growth factor (EGF) receptor. However, in several cell systems in which it inhibits growth, genistein does not alter tyrosine phosphorylation of the EGF receptor or other tyrosine kinase substrates thought to be involved in signal transduction pathways, suggesting that other mechanisms may be responsible for its action. Alternatives include inhibition of DNA topoisomerase II activity, regulation of cell cycle checkpoints, and antiangiogenic and antioxidant activity. Experiments in our laboratory suggest a new concept, that genistein may inhibit cell growth by modulating transforming growth factor (TGF) beta1 signaling pathways. Such a link between genistein action and TGFbeta1 function is supported by preliminary results of studies in patients with hereditary hemorrhagic telangiectasia (a genetic disorder involving mutations in proteins that regulate TGFbeta receptor complex formation and signaling) in which several patients had dramatic attenuation of their symptoms after 1 wk of ingesting soy-based beverages. These preclinical studies in combination with our cell culture data suggest that the mechanism of genistein involves, if not requires, TGFbeta1-signaling.

Early results of laparoscopic surgery for colorectal cancer. Retrospective analysis of 372 patients treated by Clinical Outcomes of Surgical Therapy (COST) Study Group

This study was undertaken to determine the early experience of the embers of the COST Study Group with colorectal cancer treated by laparoscopic approaches.

METHOD

A retrospective review was performed of all patients with colorectal cancer treated with laparoscopy by the COST Study Group before August 1994. Tumor site, stage, differentiation, procedure completion, presence of recurrence (local, distant, trocar site), and cause of death were analyzed.

RESULTS

A total of 372 patients with adenocarcinoma of the colon and rectum were treated by laparoscopic approach between October 1991 and August 1994 (170 men and 192 women): right colectomy, 170; sigmoid colectomy, 55; low anterior resection, 56; abdominoperineal resection, 44; left colectomy, 22; colostomy, 8; total colectomy, 6; transverse colectomy, 7; exploration, 2. Conversion to an open procedure was required in 15.6 percent of cases. Operative mortality was 2 percent. Tumor characteristics were as follows: TNM state: I, 40 percent; II, 25 percent; III, 18 percent; IV, 17 percent; Differentiation: well-moderate, 88 percent; poor, 12 percent; carcinomatosis, 5 percent. Local (3.6 percent) and distant implantation occurred in four patients (1.1 percent). Only one of these patients died a cancer-related death (Stage III at 36 months). Cancer-related death rates increased with increasing stage of tumor: I, -4 percent; II, 17 percent; III, 31 percent; IV, 70 percent.

CONCLUSION

A laparoscopic approach to colorectal cancer results in early outcome after treatment that is comparable with conventional therapy for colorectal cancer. A randomized trial is needed to compare long-term outcomes of open and laparoscopic approaches with colorectal cancer.

Mitral annulus velocity in the evaluation of left ventricular diastolic function in atrial fibrillation

This study assessed the clinical utility of mitral annulus velocity in the evaluation of left ventricular diastolic function in patients with atrial fibrillation. Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice. The clinical usefulness of conventional Doppler indexes is limited in atrial fibrillation because of the altered left atrial pressure and loss of synchronized atrial contraction. Mitral inflow and mitral annulus velocities were measured simultaneously with tau in 27 patients with nonrheumatic atrial fibrillation at the cardiac catheterization laboratory. Among deceleration time of mitral inflow, peak mitral inflow velocity (E), and peak diastolic mitral annulus velocity (E), only E correlated with tau (r = 0.51, P =.007). Prolonged tau (>/=50 ms) could be predicted by E <8 cm/s with a sensitivity of 73% (16 of 22) and a specificity of 100% (5 of 5). The E/E ratio correlated with left ventricular filling pressure (r = 0.79, P <.001). The E/E ratio of >/=11 could predict elevated left ventricular filling pressure (>/=15 mm Hg) with a sensitivity of 75% (9 of 12) and a specificity of 93% (14 of 15). Mitral annulus velocity is useful in the detection of impaired left ventricular relaxation and estimation of filling pressure even in patients with atrial fibrillation.

Inhibitor binding changes domain mobility in the iron-sulfur protein of the mitochondrial bc1 complex from bovine heart

We have analyzed crystal structures of cytochrome bc1 complexes with electron transfer inhibitors bound to the ubiquinone binding pockets Qi and/or Qo in the cytochrome b subunit. The presence or absence of the Qi inhibitor antimycin A did not affect the binding of the Qo inhibitors. Different subtypes of Qo inhibitors had dramatically different effects on the mobility of the extramembrane domain of the iron-sulfur protein (ISP): Binding of 5-undecyl-6-hydroxy-4, 7-dioxobenzothiazol and stigmatellin (subtype Qo-II and Qo-III, respectively) led to a fixation of the ISP domain on the surface of cytochrome b, whereas binding of myxothiazol and methoxyacrylate-stilbene (subtype Qo-I) favored release of this domain. The native structure has an empty Qo pocket and is intermediate between these extremes. On the basis of these observations we propose a model of quinone oxidation in the bc1 complex, which incorporates fixed and loose states of the ISP as features important for electron transfer and, possibly, also proton transport.

Sleep-disordered breathing and neuropsychological deficits. A population-based study

The relationship of sleep-disordered breathing (SOB) to neuropsychological deficits was investigated with cross-sectional data from the Wisconsin Sleep Cohort Study, a population-based study of the natural history of SDB. A sample of 841 employed men and women ages 30 to 60 yr was studied by overnight polysomnography to assess the frequency of apneas and hypopneas per hour of sleep (apnea-hypopnea index, AHI). Prior to overnight polysomnography, the participants were given a battery of neuropsychological tests for functionally important capacities including motor skills, attention, concentration, information processing, and memory. Principal factor analysis of all the neuro-psychological test data revealed a psychomotor efficiency and a memory factor. Multiple regression analysis showed a significant negative association between logarithmically transformed AHI (LogAHI) and psychomotor efficiency score independent of age, gender, and educational status (p = 0.017). The relationship was not explained by self-reported sleepiness. No significant relationship was seen between LogAHI and memory score. In assessing the clinical significance of mild SDB, we estimate that an AHI of 15 is equivalent to the decrement in psychomotor efficiency associated with 5 additional yr of age, or to 50% of the decrement associated with hypnosedative use.