Retinoic acid as a chemotactic molecule in neuronal development.

We describe the results of experiments on dissociated cultures of embryonic chick neural tissue which were designed to investigate further the role of all-trans-retinoic acid (tRA) on neurite outgrowth and, by inference, on the developing nervous system in vivo. We show that tRA increases both the number of neurites and the length of neurites extending from these chick neural tube cells at nM concentrations. Secondly, using the newly designed Dunn chamber in which stable gradients of compounds can be generated, we show that neurites respond to a gradient of tRA by growing up the gradient. These observations indicate a role for RA in vivo, not only in the initial outgrowth of neurites, but also in their guidance to the appropriate targets.

Apoptosis in cerebellar granule neurones: involvement of interleukin-1 beta converting enzyme-like proteases.

Proteases of the interleukin-1 beta converting enzyme (ICE) family have been implicated as mediators of apoptosis in several cell types. Here we report the ability of peptide inhibitors of ICE-like proteases to inhibit apoptosis of cultured cerebellar granule neurones caused by reduction of extracellular K+ levels and by the broad-spectrum protein kinase inhibitor staurosporine. Unlike apoptosis induced by K+ deprivation, staurosporine-induced neuronal death does not require new protein synthesis. The ICE-like protease inhibitor benzyloxycarbonyl-Val-Ala-Asp (O-methyl)fluoromethyl ketone (zVAD-fmk) was found to be extremely effective at preventing staurosporine-induced death of cerebellar granule neurones and yet was completely ineffective in preventing K+ deprivation-induced death. Staurosporine induced cleavage of the 116-kDa poly (ADP-ribose) polymerase enzyme, a substrate of ICE-like proteases, to the 85-kDa product, and this cleavage was also blocked by zVAD. By comparison, K+ deprivation led to the disappearance of the 116-kDa protein, with no detectable increase in level of the 85-kDa cleavage product. Taken together, these results imply the existence of divergent ICE-like protease pathways in a CNS model of neuronal apoptosis.

The Genome Sequence DataBase version 1.0 (GSDB): from low pass sequences to complete genomes.

The Genome Sequence DataBase (GSDB) has completed its conversion to an improved relational database. The new database, GSDB 1.0, is fully operational and publicly available. Data contributions, including both original sequence submissions and community annotation, are being accomplished through the use of a graphical client-server interface tool, the GSDB Annotator, and via GIO (GSDB Input/Output) files. Data retrieval services are being provided through a new Web Query Tool and direct SQL. All methods of data contribution and data retrieval fully support the new data types that have been incorporated into GSDB, including discontiguous sequences, multiple sequence alignments, and community annotation.

The Genome Sequence DataBase (GSDB): meeting the challenge of genomic sequencing.

The genome sequence database (GSDB) is a complete, publicly available relational database of DNA sequences and annotation maintained by the National Center for Genome Resources (NCGR) under a Cooperative Agreement with the US Department of Energy (DOE). GSDB provides direct, client- server access to the database for data contributions, community annotation and SQL queries. The GSDB Annotator, a multi-platform graphic user interface, is freely available. Automatically updated relational replicates of GSDB are also freely available.

Eradication of poliomyelitis in South Africa.

An international campaign under the leadership of the World Health Organisation is underway to eradicate polio from the world by the year 2000. South Africa may already be free of polio. However, to ensure eradication we need to move from a polio control programme to a polio eradication programme. This necessitates the institution of a surveillance programme for acute flaccid paralysis (AFP) and improvement of the delivery of polio vaccine. All children with AFP (including those with suspected Guillain-Barré syndrome) should be investigated with stool culture to exclude polio. Primary care services need strengthening so that oral polio vaccine coverage greater than 90% is achieved in all regions by all authorities. Outbreak response activities need to be developed. Consideration needs to be given to national immunisation days and mopping-up activities.

Laboratory surveillance of viral meningitis by examination of cerebrospinal fluid in Cape Town, 1981-9.

Nine years accumulated laboratory data derived from the culture of the cerebrospinal fluid of 11,360 aseptic meningitis cases were retrospectively reviewed to establish the epidemiology of viral meningitis in Cape Town. Virus was isolated from 3406 of the cases (91% enteroviruses and 9% mumps). Five major summer viral meningitis episodes were documented: two of echovirus 4 (706 and 445 cases), echovirus 9 (223), coxsackie A9 (104) and one of unidentified enterovirus (324 cases--probably echo 9). Although coxsackie B was endemic, clusters of one or other type were dominant at any one time. Mumps was endemic. Sixty-two percent of all viral cases were < 5 years old. The median ages of 4 and 5 years in echoviruses 9 and 4 (the epidemic strains) contrasted with that of 1 year in coxsackie B (with many cases < 3 months old). Mumps peaked at 3-4 years of age. Males dominated overall, particularly in mumps.

GenBank.

The GenBank nucleotide sequence database now contains sequence data and associated annotation corresponding to 85,000,000 nucleotides in 67,000 entries from a total of 3,000 organisms. The input stream of data coming into the database is primarily as direct submissions from the scientific community on electronic media, with little or no data being keyboarded from the printed page by the databank staff. The data are maintained in a relational database management system and are made available in flatfile form through on-line access, and through various network and off-line computer-readable media. The data are also distributed in relational form through satellite copies at a number of institutions in the U.S. and elsewhere. In addition, GenBank provides the U.S. distribution center for the BIOSCI electronic bulletin board service.

GenBank.

The GenBank nucleotide sequence database now contains sequence data and associated annotation corresponding to 56,000,000 nucleotides in 45,000 entries. The input stream of data coming into the database has largely been shifted to direct submissions from the scientific community on electronic media. The data have been installed in a relational database management system and are made available in this form through on-line access, and through various network and off-line computer-readable media. In addition, GenBank provides the U.S. distribution center for the BIOSCI electronic bulletin board service.

Factors influencing the accumulation in fibrous plaques of lipid derived from low density lipoprotein. I. Relation between fibrin and immobilization of apo B-containing lipoprotein.

The lipid that accumulates in some fibrous atherosclerotic lesions appears to be derived from plasma low density lipoprotein (LDL). An early stage in lipid accumulation may be immobilization of a fraction of the LDL, and this is released by incubation with proteolytic enzymes, of which the most effective is the fibrinolytic enzyme, plasmin. We have examined the relationship between release of fibrin degradation products (FDP) and LDL in controlled plasmin incubations of 42 samples of normal intima and atherosclerotic lesions from aortas of 10 patients. In three patients (group 1) no LDL was released from any of the 11 tissue samples although they comprised lesions as well as normal intima. In 2 more patients (group 2) LDL was consistently low. However, in 5 patients (group 3) substantial amounts of LDL were released from all 21 tissue samples, and there was a significant correlation between the amounts of FDP and LDL (P less than 0.001). In spite of this correlation there were marked differences in the ratio FDP/LDL, but analysis by SDS-polyacrylamide gel electrophoresis and immuno blotting of the FDP released showed no consistent pattern related to LDL binding. Although the ratio FDP/LDL showed a 4-fold range, in 6 lesions subjected to successive 2-h incubations with plasmin the ratio within each lesion remained constant, supporting the concept that fibrin and LDL are linked.

Fate of fibrinogen in human arterial intima.

Fibrinogen and fibrinogen/fibrin-related antigen (total FRA) was measured in human normal intima and different types of atherosclerotic lesions and mural thrombi. The amount showed marked variation between groups of tissue samples, but within each group there was a significant correlation between levels of total FRA and low density lipoprotein (LDL), suggesting that some common factor must influence their influx or retention. The total FRA were analyzed by gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting with antisera to whole fibrinogen and fragments D and E, and fibrinopeptide A (FPA). All intimal samples (but not thrombi) contained fragment X, the first product of plasmin digestion of fibrinogen, but fragment Y was present in only half the samples, and no core-fragment E containing FPA was detected in any sample, suggesting that fibrinogenolysis is limited. By contrast, all samples contained fragment E, which was negative for FPA, so presumably derived from fibrin; they also contained fragments D-dimer and DY, which are characteristic degradation products of cross-linked fibrin. There were no differences between samples obtained during reconstructive vascular surgery and samples obtained at autopsy, so the patterns appear to represent the steady state. This implies that within the intima there is continuous formation of cross-linked fibrin and continuous fibrinolysis, both processes generating fragments that may have atherogenic properties.

Two new genome types of adenovirus 7c.

Adenovirus type 7 is the type most frequently associated with serious disease. Eighteen different genome types of adenovirus type 7 had been reported up to October 1986. The genome type Ad7c, based on the restriction enzyme profiles of SmaI and BamHI, has been reported from Europe prior to 1969 and more recently from South Africa. Here, we report two new genome types of adenovirus 7 c that have not previously been identified and that have been isolated in South Africa between 1975 and 1986 from children with postmeasles pneumonia. The two new genome types differ from the prototype Ad7c virus in having two (Ad7c1) or one (Ad7c2) extra cleavage sites for the restriction endonuclease EcoRI. These sites have been located at 3.68kb and 5.32kb from the left terminus of the genome map published for the prototype Ad7c strain. A strain resembling the prototype Ad7c was also isolated in 1986 from a case of post measles pneumonia.

The surface growth and activity ofNitrobacter.

The effect of surface attachment on oxidation of nitrite to nitrate byNitrobacter was studied in batch culture, on glass coverslips, and in continuous culture on glass beads and anion exchange resin beads in an air-lift column fermenter. In batch culture, the surfaces stimulated specific growth rate, while in continuous culture, activity of attached cells was less than that of freely suspended cells. Nitrate productivity, free cell productivity, and attached cell concentration increased exponentially at the same specific rate, termed the colonization rate, and nitrate productivity was found to be a convenient estimate of biomass concentration. Permanent attachment was mediated by production of slime material. Surface growth resulted in multiple steady states and the ability to respond quickly to changes in dilution rate. The air-lift column fermenter system provided a convenient system for the study of growth and activity of attached cells and was most suitable when using ion exchange resins as a substratum for attachment.

Mitogenic activity in human atherosclerotic lesions.

Focal smooth muscle cell proliferation is a key event in atherogenesis, but the stimulating factors are unknown, and there is little information on the occurrence of growth promoting factors in the arterial wall. We have tested extracts of human aortic intima for stimulation of DNA synthesis, using the chick chorioallantoic membrane (CAM) assay in an attempt to avoid artifacts arising with cultured cells. Consistently high levels of stimulation were obtained with early proliferative (gelatinous) lesions (mean DNA synthesis 188% of control, n = 6) and slightly more advanced transitional lesions (mean 160%, n = 4); results with mature fibrous plaques were variable (range 120-182%, n = 3). Significant stimulation was also given by four of eleven samples of apparently lesion-free intima. Intima contains fibrinogen and a range of fibrinogen and fibrin degradation products (FRA) and preliminary fractionation experiments suggest that activity may reside in the FRA fraction. Serum does not stimulate DNA synthesis in the CAM; extract activity was retained in FRA-containing fractions after removal of most serum proteins by affinity chromatography, but was mainly lost from serum protein-containing fractions after removal of FRA.

Spinal cord damage and operations for coarctation of the aorta: aetiology, practice, and prospects.

An inquiry was made into the clinical practice and paraplegia rate associated with operations for coarctation of the aorta conducted by surgeons in the United Kingdom and Ireland. Paraplegia occurred in 16 patients in a total of 5492 operations, an incidence of 0.3%, or once in 343 operations. The aetiology and measures that may be taken to avoid this complication are discussed. The medicolegal consequences need no emphasis and it is recommended that finger palpation alone as a method of assessing the adequacy of distal aortic pressure should be abandoned in favour of continuous electromanometric visual display of the aortic pressure in all patients. In the long term, serious consideration must be given to developing spinal cord monitoring using somatosensory evoked potentials.

Onset of right-to-left shunting through a foramen ovale in a 70-year-old woman: successful surgical treatment.

A 70-year-old woman presented with disabling breathlessness. She was found to have severe arterial hypoxaemia due to isolated right-to-left shunting through a patent foramen ovale. In the absence of pulmonary hypertension or evidence of right ventricular dysfunction this is attributed to reduced right atrial compliance. The phasic nature of the shunt, which occurred only during atrial filling, supports this view. Surgical closure of the foramen abolished the hypoxaemia and her symptoms.