Detection of widespread fluids in the Tibetan crust by magnetotelluric studies

Magnetotelluric exploration has shown that the middle and lower crust is anomalously conductive across most of the north-to-south width of the Tibetan plateau. The integrated conductivity (conductance) of the Tibetan crust ranges from 3000 to greater than 20,000 siemens. In contrast, stable continental regions typically exhibit conductances from 20 to 1000 siemens, averaging 100 siemens. Such pervasively high conductance suggests that partial melt and/or aqueous fluids are widespread within the Tibetan crust. In southern Tibet, the high-conductivity layer is at a depth of 15 to 20 kilometers and is probably due to partial melt and aqueous fluids in the crust. In northern Tibet, the conductive layer is at 30 to 40 kilometers and is due to partial melting. Zones of fluid may represent weaker areas that could accommodate deformation and lower crustal flow.

In vivo and in vitro gene transfer to mammalian somatic cells by particle bombardment

Chimeric chloramphenicol acetyltransferase and beta-galactosidase marker genes were coated onto fine gold particles and used to bombard a variety of mammalian tissues and cells. Transient expression of the genes was obtained in liver, skin, and muscle tissues of rat and mouse bombarded in vivo. Similar results were obtained with freshly isolated ductal segments of rat and human mammary glands and primary cultures derived from these explants. Gene transfer and transient expression were also observed in eight human cell culture lines, including cells of epithelial, endothelial, fibroblast, and lymphocyte origin. Using CHO and MCF-7 cell cultures as models, we obtained stable gene transfer at frequencies of 1.7 x 10(-3) and 6 x 10(-4), respectively. The particle bombardment technology thus provides a useful means to transfer foreign genes into a variety of mammalian somatic cell systems. The method is applicable to tissues in vivo as well as to isolated cells in culture and has proven effective with all cell or tissue types tested thus far. This technology may therefore prove to be applicable in various aspects of gene therapy.

The nucleoplasmin nuclear location sequence is larger and more complex than that of SV-40 large T antigen

The carboxy-terminal tail of nucleoplasmin, which specifies entry into the cell nucleus, contains four short sequences that are similar to previously identified nuclear location sequences. We show that none of these is able to locate chicken muscle pyruvate kinase to the cell nucleus. Deletion analysis was used to determine the limits of a nuclear location sequence and indicated that a 14-amino acid segment (RPAATKKAGQAKKK) should function as a minimal nuclear location sequence. When tested directly, however, this sequence was unable to locate pyruvate kinase to the cell nucleus. Restoration of three amino acids of nucleoplasmin sequence at either end of this sequence generated sequences that were able to locate pyruvate kinase to the cell nucleus. The 14-amino acid proposed minimal nuclear location sequence is present in the functional sequences, AVKRPAATKKAGQAKKK, RPAATKKAGQAKKKKLD, and the sequence AVKRPAATKKAGQAKKKKLD, which has additional amino acids at both ends. The minimal sequence element is therefore necessary but not sufficient for transport into the cell nucleus. This unusual feature of the nucleoplasmin nuclear location sequence suggests ways in which it could interact with the nuclear transport mechanism.

Immunizing patients with metastatic melanoma using recombinant adenoviruses encoding MART-1 or gp100 melanoma antigens

BACKGROUND

The characterization of the genes encoding melanoma-associated antigens MART-1 or gp100, recognized by T cells, has opened new possibilities for the development of immunization strategies for patients with metastatic melanoma. With the use of recombinant adenoviruses expressing either MART-1 or gp100 to immunize patients with metastatic melanoma, we evaluated the safety, immunologic, and potential therapeutic aspects of these immunizations.

METHODS

In phase I studies, 54 patients received escalating doses (between 10(7) and 10(11) plaque-forming units) of recombinant adenovirus encoding either MART-1 or gp100 melanoma antigen administered either alone or followed by the administration of interleukin 2 (IL-2). The immunologic impact of these immunizations on the development of cellular and antibody reactivity was assayed.

RESULTS

Recombinant adenoviruses expressing MART-1 or gp100 were safely administered. One of 16 patients with metastatic melanoma receiving the recombinant adenovirus MART-1 alone experienced a complete response. Other patients achieved objective responses, but they had received IL-2 along with an adenovirus, and their responses could be attributed to the cytokine. Immunologic assays showed no consistent immunization to the MART-1 or gp100 transgenes expressed by the recombinant adenoviruses. High levels of neutralizing antibody were found in the pretreatment sera of the patients.

CONCLUSIONS

High doses of recombinant adenoviruses could be safely administered to cancer patients. High levels of neutralizing antibody present in patients' sera prior to treatment may have impaired the ability of these viruses to immunize patients against melanoma antigens.

Selective glial vulnerability following transient global ischemia in rat brain

Global cerebral ischemia selectively damages neurons, but its contribution to glial cell death is uncertain. Accordingly, adult male rats were sacrificed by perfusion fixation at 1, 2, 3, 5, and 14 days following 10 minutes of global ischemia. This insult produces CA1 hippocampal neuronal death at post-ischemic (PI) day 3, but minor or no damage to neurons in other regions. In situ end labeling (ISEL) and immunohistochemistry identified fragmented DNA of dead or dying glia and distinguished glial subtypes. Rare ISEL-positive oligodendroglia, astrocytes, and microglia were present in control brain. Apoptotic bodies and ISEL-positive glia significantly increased at PI day 1 in cortex and thalamus (p < 0.05), but were similar to controls in other regions and at other PI intervals. Most were oligodendroglia, although ISEL-positive microglia and astrocytes were also observed. These results show that oligodendroglia die rapidly after brief global ischemia and are more sensitive than neurons in certain brain regions. Their selective vulnerability to ischemia may be responsible for the delayed white matter damage following anoxia or CO poisoning or that associated with white matter arteriopathies. Glial apoptosis could contribute to the DNA ladders of apoptotic oligonucleosomes that have been found in post-ischemic brain.

Brevetoxicosis in manatees (Trichechus manatus latirostris) from the 1996 epizootic: gross, histologic, and immunohistochemical features

In 1996, at least 149 manatees (Trichechus manatus latirostris) died in an unprecedented epizootic along the southwest coast of Florida. At about the same time, a bloom of the brevetoxin-producing dinoflagellates, Gymnodinium breve, was present in the same area. Grossly, severe nasopharyngeal, pulmonary, hepatic, renal, and cerebral congestion was present in all cases. Nasopharyngeal and pulmonary edema and hemorrhage were also seen. Consistent microscopic lesions consisted of catarrhal rhinitis, pulmonary hemorrhage and edema, multiorgan hemosiderosis, and nonsuppurative leptomeningitis. Immunohistochemical staining using a polyclonal primary antibody to brevetoxin (GAB) showed intense positive staining of lymphocytes and macrophages in the lung, liver, and secondary lymphoid tissues. Additionally, lymphocytes and macrophages associated with the inflammatory lesions of the nasal mucosa and meninges were also positive for brevetoxin. These findings implicate brevetoxicosis as a component of and the likely primary etiology for the epizootic. The data suggest that mortality resulting from brevetoxicosis may not necessarily be acute but may occur after chronic inhalation and/or ingestion. Immunohistochemical staining with interleukin-1-beta-converting enzyme showed positive staining with a cellular tropism similar to GAB. This suggests that brevetoxicosis may initiate apoptosis and/or the release of inflammatory mediators that culminate in fatal toxic shock.

Popliteal artery aneurysms: current management and outcome

PURPOSE

Thrombosis of popliteal artery aneurysms can produce limb-threatening ischemia. In this setting we have found preoperative thrombolytic therapy to be beneficial.

METHODS

Thirty-three patients with 54 popliteal artery aneurysms were studied (mean follow-up 62 months). Twenty-one patients (62%) had bilateral popliteal artery aneurysms, and 20 patients (61%) had extrapopliteal arterial aneurysms. Thirty-three (61%) aneurysms had symptoms of compression or ischemia, and 21 (39%) aneurysms had thrombosis. A trend toward thrombosis for larger aneurysms was noted (p < 0.068).

RESULTS

Forty-five aneurysms were treated with bypass grafting. Five-year graft patency and limb salvage rates were 71% and 90%, respectively. Factors favoring graft patency and limb salvage included presence of two- or three-vessel runoff compared with patients with single- or no-vessel runoff (p < 0.025 graft patency; p < 0.003 limb salvage) and presence of a patent aneurysm (p < 0.005 graft patency and limb salvage). Seven patients diagnosed with thrombosis of their aneurysm and all runoff vessels were treated with preoperative thrombolytic therapy. Complete clearing of thrombus from these arteries was achieved in six of these patients (and from two of these runoff vessels in the remaining patient). These patients had better graft patency (p < 0.005) and limb salvage (p < 0.01) than comparable patients treated with emergency operations. Six amputations were performed in the follow-up interval, none of which were performed in patients having undergone thrombolytic therapy.

CONCLUSIONS

It is concluded that popliteal aneurysms are managed best by elective repair of patent aneurysms with good runoff. In that difficult situation of the thrombosed popliteal artery aneurysm associated with acute leg ischemia, thrombolytic therapy safely and effectively provides patients with a more favorable alternative than emergency surgery.

DNA fragmentation follows delayed neuronal death in CA1 neurons exposed to transient global ischemia in the rat

Apoptosis is an active, gene-directed process of cell death in which early fragmentation of nuclear DNA precedes morphological changes in the nucleus and, later, in the cytoplasm. In ischemia, biochemical studies have detected oligonucleosomes of apoptosis whereas sequential morphological studies show changes consistent with necrosis rather than apoptosis. To resolve this apparent discrepancy, we subjected rats to 10 minutes of transient forebrain ischemia followed by 1 to 14 days of reperfusion. Parameters evaluated in the CA1 region of the hippocampus included morphology, in situ end labeling (ISEL) of fragmented DNA, and expression of p53. Neurons were indistinguishable from controls at postischemic day 1 but displayed cytoplasmic basophilia or focal condensations at day 2; some neurons were slightly swollen and a few appeared normal. In situ end labeling was absent. At days 3 and 5, approximately 40 to 60% of CA1 neurons had shrunken eosinophilic cytoplasm and pyknotic nuclei, but only half of these were ISEL. By day 14, many of the necrotic neurons had been removed by phagocytes; those remaining retained mild ISEL. Neither p53 protein nor mRNA were identified in control or postischemic brain by in situ hybridization with riboprobes or by northern blot analysis. These results show that DNA fragmentation occurs after the development of delayed neuronal death in CA1 neurons subjected to 10 minutes of global ischemia. They suggest that mechanisms other than apoptosis may mediate the irreversible changes in the CA1 neurons in this model.

Non-Hodgkin's lymphoma: case control epidemiological study in Yorkshire

This paper reports the results of a case control study of non-Hodgkin's lymphoma in the Yorkshire Health Region. In all, 437 cases and 724 controls were interviewed. Risk factors associated with past skin conditions, family history of cancer and infectious mononucleosis, aspects of social life and contact with wood dust and epoxy glues all emerge. A comparison of high and low grade morphological forms of disease reveal contrasting risks and suggest separate aetiologies for these conditions.

Seroprevalence of HTLV-1 and HTLV-2 among intravenous drug users and persons in clinics for sexually transmitted diseases

Background. The human T-cell lymphotropic virus Type I (HTLV-I) is associated with adult T-cell leukemia and myelopathy, whereas HTLV-II infection has uncertain clinical consequences. We assessed the seroprevalence of these retroviruses among intravenous drug users and among patients seen at clinics for sexually transmitted diseases (STD clinics).

METHODS

We used serum samples that were collected in eight cities in 1988 and 1989 during surveys of human immunodeficiency virus infection among intravenous drug users entering treatment and persons seen in STD clinics. The serum samples were tested for antibodies to HTLV, and positive specimens were tested further by a synthetic peptide-based enzyme-linked immunosorbent assay to differentiate between HTLV-I and HTLV-II.

RESULTS

Among 3217 intravenous drug users in 29-drug-treatment centers, the median seroprevalence rates of HTLV varied widely according to city (range, 0.4 percent in Atlanta to 17.6 percent in Los Angeles). Seroprevalence increased sharply with age, to 32 percent in persons over 44 years of age. HTLV infection was more common among blacks (15.5 percent) and Hispanics (10.7 percent) than among whites (4.1 percent), and it was strongly associated with a history of heroin injection (P less than or equal to 0.001). Among 5264 patients in 24 STD clinics, the median rates of HTLV infection were much lower (range, 0.1 percent in Atlanta and Newark to 2.0 percent in Los Angeles). Again, this infection was more common among intravenous drug users (7.6 percent) than among non-drug users (0.7 percent). Eighty-four percent of the seropositive samples from drug-treatment centers and 69 percent of those from STD clinics were due to HTLV-II infection (P = 0.03).

CONCLUSIONS

HTLV infections are common among intravenous drug users and are primarily caused by HTLV-II. Among patients seen at STD clinics, HTLV is strongly associated with intravenous drug use, but the retrovirus is also prevalent among non-drug users.

Rhesus macaques previously infected with simian/human immunodeficiency virus are protected from vaginal challenge with pathogenic SIVmac239

Nontraumatic vaginal inoculation of rhesus macaques with a simian/human immunodeficiency virus (SIV/HIV) chimera containing the envelope gene from HIV-1 89.6 (SHIV 89.6) results in systemic infection (Y. Lu, B. Brosio, M. Lafaile, J. Li, R. G. Collman, J. Sodroski, and C. J. Miller, J. Virol. 70:3045-3050, 1996). A total of five rhesus macaques have each been infected by exposure to at least three intravaginal inoculations of SHIV 89.6. The SHIV 89.6 infection is characterized by a transient viremia that evokes humoral and cellular immune responses to HIV and SIV antigens, but disease does not develop in animals infected with SHIV 89.6. To determine if a previous infection with SHIV 89.6 by vaginal inoculation could protect animals from vaginal challenge with pathogenic SIV, all five animals were intravaginally inoculated twice with pathogenic SIV-mac239. After challenge, all of the SHIV-immunized animals had low or undetectable viral RNA levels in plasma compared to control animals. Three of the five of the SHIV-immunized animals remained virus isolation negative for more than 8 months, while two became virus isolation positive. The presence of SIV Gag-specific cytotoxic T lymphocytes in peripheral blood mononuclear cells and SIV-specific antibodies in cervicovaginal secretions at the time of challenge was associated with resistance to pathogenic SIV infection after vaginal challenge. These results suggest that protection from sexual transmission of HIV may be possible by effectively stimulating both humoral and cellular antiviral immunity in the systemic and genital mucosal immune compartments.

Clinical evaluation of USCOM ultrasonic cardiac output monitor in cardiac surgical patients in intensive care unit

BACKGROUND

The USCOM ultrasonic cardiac output monitor (USCOM Pty Ltd, Coffs Harbour, NSW, Australia) is a non-invasive device that determines cardiac output by continuous-wave Doppler ultrasound. The aim of this study was to evaluate the accuracy of the USCOM device compared with the thermodilution technique in intensive care patients who had just undergone cardiac surgery.

METHODS

We conducted a prospective study in the 18-bed intensive care unit of a 600-bed tertiary referral hospital. Twenty-four mechanically ventilated patients were studied immediately following cardiac surgery. We evaluated the USCOM monitor by comparing its output with paired measurements obtained by the standard thermodilution technique using a pulmonary artery catheter.

RESULTS

Forty paired measurements were obtained in 22 patients. We were unable to obtain an acceptable signal in the remaining two patients. Comparison of the two techniques showed a bias of 0.18 and limits of agreement of -1.43 to 1.78. The agreement may not be as good between techniques at higher cardiac output values.

CONCLUSIONS

The USCOM monitor has a place in intensive care monitoring. It is accurate, rapid, safe, well-tolerated, non-invasive and cost-effective. The learning curve for skill acquisition is very short. However, during the learning phase the USCOM monitor measurements are rather 'operator dependent'. Its suitability for use in high and low cardiac output states requires further validation.

Psychiatric research ethics: an overview of evolving guidelines and current ethical dilemmas in the study of mental illness

The field of psychiatry has an opportunity to construct a more refined, perhaps more enduring understanding of the ethical basis of mental illness research. The aim of this paper is to help advance this understanding by 1) tracing the evolution of the emerging ethic for biomedical experimentation, including recent recommendations of the President's National Bioethics Advisory Commission, and 2) reviewing data and concepts related to compelling ethical questions now faced in the study of mental disorders. Empirical findings on informed consent, the ethical safeguards of institutional review and surrogate decision making, and the relationship between scientific and ethical imperatives are outlined. Psychiatric researchers will increasingly be called upon to justify their scientific approaches and to seek ways of safeguarding the well-being of people with mental illness who participate in experiments. Most importantly, psychiatric investigators will need to demonstrate their appreciation and respect for ethical dimensions of investigation with special populations. Further empirical study and greater sophistication with respect to the distinct ethical issues in psychiatric research are needed. Although such measures present many challenges, they should not interfere with progress in neuropsychiatric science so long as researchers in our field seek to guide the process of reflection and implementation.

Detection of HIV-1 gene sequences in hippocampal neurons isolated from postmortem AIDS brains by laser capture microdissection

We employed laser capture microdissection to remove individual pyramidal neurons from the CA1, CA3, and CA4 regions of formalin-fixed, paraffin-embedded hippocampus from 8 AIDS brains and 2 HIV-1-seronegative normal brains. We amplified HIV-1 gag and nef gene sequences using separate, double round PCR reactions for each of the primer sets. In all 3 hippocampal regions, amplification efficiency was best with sequence length between 284 and 324 bp; HIV-1 nef gene sequences were more common than HIV-1 gag sequences; and rank order for percent positive amplification was CA3 > CA4 > CA1 samples. These results are the first to detect HIV-1 gene sequences in microdissected human tissue. They indicate that brain neurons in vivo contain HIV-1 DNA sequences consistent with latent infection by this virus, and suggest that neurons display a selective vulnerability for HIV infection. Neuronal HIV infection could contribute to neuronal injury and death or act as a potential viral reservoir if reactivated.

Cloning and characterization of the genes encoding the murine homologues of the human melanoma antigens MART1 and gp100

The recent identification of genes encoding melanoma-associated antigens has opened new possibilities for the development of cancer vaccines designed to cause the rejection of established tumors. To develop a syngeneic animal model for evaluating antigen-specific vaccines in cancer therapy, the murine homologues of the human melanoma antigens MART1 and gp100, which were specifically recognized by tumor-infiltrating lymphocytes from patients with melanoma, were cloned and sequenced from a murine B16 melanoma cDNA library. The open reading frames of murine MART1 and gp100 encode proteins of 113- and 626-amino acids with 68.8 and 77% identity to the respective human proteins. Comparison of the DNA sequences of the murine MART1 genes, derived from normal melanocytes, the immortalized nontumorgenic melanocyte line Melan-a and the B16 melanoma, showed all to be identical. Northern and Western blot analyses confirmed that both genes encoded products that were melanocyte lineage proteins. Mice immunized with murine MART1 or gp100 using recombinant vaccinia virus failed to produce any detectable T-cell responses or protective immunity against B16 melanoma. In contrast, immunization of mice with human gp100 using recombinant adenoviruses elicited T cells specific for hgp100, but these T cells also cross reacted with B16 tumor in vitro and induced significant but weak protection against B16 challenge. Immunization with human and mouse gp100 together [adenovirus type 2 (Ad2)-hgp100 plus recombinant vaccinia virus (rVV)-mgp100], or immunization with human gp100 (Ad2-hgp100) and boosting with heterologous vector (rVV-hgp100 or rVV-mgp100) or homologous vector (Ad2-hgp100), did not significantly enhance the protective response against B16 melanoma. These results may suggest that immunization with heterologous tumor antigen, rather than self, may be more effective as an immunotherapeutic reagent in designing antigen-specific cancer vaccines.

Cloning of the goat beta-casein-encoding gene and expression in transgenic mice

The goat beta-casein-encoding gene (CSN2), which encodes the most abundant protein of goat milk, has been cloned and sequenced. The intron/exon organization of the 9.0-kb goat CSN2 gene is similar to that of other CSN2 genes. Expression of the goat gene was principally restricted to the mammary gland of lactating transgenic animals. A low level of expression was also observed in skeletal muscle and skin. In contrast to a rat CSN2 transgene [Lee et al., Nucleic Acids Res. 16 (1988) 1027-1041], the goat gene was expressed to a high degree in the lactating mammary gland. Differences in the content or context of regulatory elements may account for the enhanced performance of the goat relative to the rat CSN2 gene in transgenic mice.

Patients' experiences of Parkinson's disease

Patients' (n = 101) experiences of Parkinson's disease (PD) were studied through structured interviews. Oblique factor analysis produced three moderately intercorrelated clusters of items reflecting reported severity of motoric, cognitive, and psychological problems, respectively. Scales formed from the factors were correlated with demographic, disease-related, and psychosocial variables. The demographic variables were not significantly correlated with the scales or with any other variables in the set. Hoehn and Yahr staging was significantly related to scores only on the motoric severity scale. Measures of functional capacity, in contrast, were significantly associated with all three scales. Although the addition of the psychosocial variables as a set significantly increased multiple Rs for each of the three scales, the specific patterns of correlation varied from scale to scale. The findings indicate that from the viewpoint of the patient the problems created by PD were not restricted to the motoric domain. Too narrow a focus by clinicians and researchers on medical symptomatology may give insufficient recognition to the multidimensional nature of the patient's experience.

Detection of viral ribonucleic acid and histologic analysis of inflamed synovium in Ross River virus infection

OBJECTIVE

To document the histology of Ross River virus (RRV) arthritis and to examine inflamed synovium for viral RNA.

METHODS

Biopsy tissue from the inflamed knees of 12 patients with RRV infection was studied using conventional and immunostaining techniques. Reverse transcriptase-polymerase chain reaction technology was used to probe for the presence of viral RNA in the synovial biopsy samples and in serum.

RESULTS

Hyperplasia of the synovial lining layer, vascular proliferation, and mononuclear cell infiltration were the main histologic changes. RRV RNA was found in knee biopsy tissue that was obtained from 2 patients at 5 weeks after the onset of symptoms.

CONCLUSION

RRV RNA was identified in inflamed synovium more than a month after symptoms began. Inflammation was apparent in the absence of detectable virus in the majority of patients.

Diesel exhaust particles suppress macrophage function and slow the pulmonary clearance of Listeria monocytogenes in rats

In this study, we tested the hypothesis that exposure to diesel exhaust particles (DEP) may increase susceptibility of the host to pulmonary infection. Male Sprague-Dawley rats received a single dose of DEP (5 mg/kg), carbon black (CB, 5 mg/kg), or saline intratracheally. Three days later, the rats were inoculated intratracheally with approximately 5,000 Listeria monocytogenes and sacrificed at 3, 5, and 7 days postinfection, and we determined the number of viable Listeria in the left lobe of lungs. The remaining lungs underwent bronchoalveolar lavage (BAL) and the retrieved BAL cells were identified and counted. Luminol-dependent chemiluminescence, a measure of reactive oxygen species (ROS) formation, generated by BAL cells was monitored and the levels of nitric oxide and tumor necrosis factor (TNF)-[alpha] produced by macrophages in culture were determined. At 7 days postinfection, we excised the lung-draining lymph nodes and phenotyped the lymphocyte subpopulations. Exposure of rats to DEP, but not to CB, decreased the clearance of Listeria from the lungs. Listeria-induced generation of luminol-dependent chemiluminescence by pulmonary phagocytes decreased by exposure to DEP but not CB. Similarly, Listeria-induced production of NO by alveolar macrophages was negated at 3, 5, and 7 days after inoculation in DEP-exposed rats. In contrast, CB exposure had no effect on Listeria-induced NO production at 3 days after infection and had a substantially smaller effect than DEP at later days. Exposure to DEP or CB resulted in enlarged lung-draining lymph nodes and increased the number and percentage of CD4(+) and CD8(+) T cells. These results showed that exposure to DEP decreased the ability of macrophages to produce antimicrobial oxidants in response to Listeria, which may play a role in the increased susceptibility of rats to pulmonary infection. This DEP-induced suppression is caused partially by chemicals adsorbed onto the carbon core of DEP, because impaired macrophage function and decreased Listeria clearance were not observed following exposure to CB.

Enduringness and change in creative personality and the prediction of occupational creativity

Participants in a longitudinal study of women's adult development were scored at midlife on the Occupational Creativity Scale (OCS), which draws on J. L. Holland's (1985) model of vocational environments in the assessment of participants' creative achievement. College measures of cognitive-affective style and career aspirations predicted OCS scores at age 52, and consistency of creative temperament (H. G. Gough, 1992), motivation, and overall attributes of creative personality were demonstrated with both self-report and observer data over several times of testing. However, there was change along with this enduringness: Large fluctuations in creative temperament over one period of life or another were common in individuals, and OCS scores were associated with an increase in level of effective functioning over 30 years.

DAN is a secreted glycoprotein related to Xenopus cerberus

We report that DAN, a potential cell cycle regulator and tumour suppressor, is a secreted glycoprotein related to Xenopus cerberus. DAN, cerberus, its mouse relative Cer-1/cer-l/Cerberus-like/Cerr1, and the recently described factor DRM/Gremlin, appear to be members of the cystine knot superfamily, which includes TGFbetas and BMPs. Like cerberus and mCer-1, DAN-induced cement glands as well as markers of anterior neural tissue and endoderm in Xenopus animal cap assays, features of BMP signalling blockade. During mouse embryogenesis, Dan was expressed from E8.5 in cranial mesenchyme and somites, then later in limb and facial mesenchyme. The pattern in somites was highly dynamic, with transcripts initially localized to the caudal half of the nascent epithelial somite, then, after maturation, to sclerotomal cells adjacent to the neural tube. Dan was also expressed in the developing myotome. The expression domains include sites in which BMP inhibition is known to be important for development. Thus, DAN appears to be a secreted factor belonging to the cystine knot superfamily, and one of a growing number of antagonists acting to modulate BMP signalling during development.

Effects of differences in timbre on sequential grouping

Differences in the timbre of sounds in a sequence can affect their perceptual organization. Using a performance measure, Hartmann and Johnson (1991) concluded that streaming could be predicted primarily by the extent to which sounds were passed by different peripheral channels. However, results from a rating task by Dannenbring and Bregman (1976) suggested that sounds in the same spectral region (passed by the same peripheral channels) can be allocated to different streams. In Experiment 1, it was found, using an interleaved melody task, that target sounds could be selected from distractors in the same spectral region more easily when they differed in timbre. This finding might result from primitive stream segregation or schema-driven selection, but not from peripheral channeling. In Experiment 2, a rhythm discrimination task was used, requiring the sounds to be integrated for good performance. Differences in timbre impaired performance, indicating the occurrence of primitive stream segregation.

Hodgkin's disease: case control epidemiological study in Yorkshire

This is the first report of a case-control epidemiological study on lymphomas and leukaemias occurring in Yorkshire during 1979-84. This paper deals with the results of the Hodgkin's disease analysis comprising 248 cases and 489 controls. The results indicate support for previous work with respect to small family size and past history of infectious mononucleosis. Positive observations made in a previous pilot study are also confirmed and extended with respect to associations with certain chronic skin lesions, dental anaesthesia and familial factors. Negative associations are described with respect to X-ray exposures and cigarette smoking. It is proposed that these results fit into a general hypothesis that these conditions are the result of interaction between infectious agents and altered immunity in those persons genetically predisposed.