Early neurogenesis of the Drosophila brain

We have studied the formation of the neuroblasts of the Drosophila brain which segregate from the procephalic neurectoderm. The expression domains of the segment polarity gene engrailed (en) allow one to subdivide the procephalic neuroectoderm into tritocerebral, deuterocerebral, and protocerebral neuromeres. Based upon the expression pattern of the proneural gene lethal of scute (l'sc), as well as the pattern of brain neuroblast segregation, the protocerebral and deuterocerebral neuromeres can be further subdivided into a central, anterior, and posterior domain. A total of 75-80 neuroblasts segregate in a stereotyped pattern from the procephalic neurectoderm of each side during stages 9-11. With respect to their position and the expression of the markers asense (ase) and seven-up (svp), 23 small groups of one to five neuroblasts each were identified. The first eight groups (Pc1-4, Dc1-3, Dp1), collectively called SI/II neuroblasts in analogy to the subpopulation of ventral neuroblasts which appear at the same stage), arise from the central domain of the protocerebral and deuterocerebral neurectoderm, respectively. Later groups form anteriorly and posteriorly from the earlier ones, leading to a centrifugal growth of the procephalic neuroblast population. SIII neuroblasts (Pa1-4, Pp1-2, Dp2) arise during stage 10, SIV neuroblasts (Pa5-6, Pp3-4, Da1, T1-2) during early stage 11, and SV neuroblasts (Pp5, Pdm) during late stage 11 and early stage 12. The dorsomedial domain of the procephalic neurectoderm represents a special case. Unlike other procephalic neuroblasts which delaminate from the surface ectoderm as individual cells, cells of the dorsomedial protocerebral domain are internalized during stage 12 as large, coherent clusters by a movement which can be best characterized as a combination of mass-delamination and invagination.

Expression of bacteriophage T7 RNA polymerase in avian and mammalian cells by a recombinant fowlpox virus

The bacteriophage T7 RNA polymerase gene was integrated into the fowlpox virus genome under the control of the vaccinia virus early/late promoter, P7.5. The recombinant fowlpox virus, fpEFLT7pol, stably expressed T7 RNA polymerase in avian and mammalian cells, allowing transient expression of transfected genes under the control of the T7 promoter. The recombinant fowlpox virus expressing T7 RNA polymerase offers an alternative to the widely used vaccinia virus vTF7-3, or the recently developed modified vaccinia virus Ankara (MVA) T7 RNA polymerase recombinant, a highly attenuated strain with restricted host-range. Recombinant fowlpox viruses have the advantage that as no infectious virus are produced from mammalian cells they do not have to be used under stringent microbiological safety conditions.

Natural and accelerated docosahexaenoic acid accumulation in the prenatal rat brain

The quantity and distribution of docosahexaenoic acid (DHA) in major brain phospholipids (PL) was examined in the fetal rat brain before birth, using thin-layer and capillary column gas chromatography. A rapid increment of DHA content of about 187 micrograms/g brain/day was observed between 17 to 20 days gestation, as opposed to 39.3 +/- 2.9 micrograms/g brain/day prior to that. Single intraamniotic injections of 5 microL ethyl-docosahexaenoate (Et-DHA) (12 microM, 4.25 mg) administered to 17-day-old fetuses were used to examine the uptake of DHA into brain PL. Three days following injection, the amount of n-3 polyunsaturated fatty acids increased by 28% compared to ethyl-oleate (Et-Ole) injected fetuses. Compared to the n-6 fatty acid family, the relative amount of DHA increased in the phosphatidylserine (PS), phosphatidylethanolamine and phosphatidylcholine (PC) lipids by 15 (P = 0.02), 13 and 14%, respectively. A major increase in the pool size of phosphatidylinositol and PS (110 and 50.3%, respectively), and a decrease in PC (8.2%) were observed 3 d after Et-DHA as compared to Et-Ole administration. The data suggest that a single intraamniotic administration of Et-DHA can modulate membrane PL content and alter PUFA composition.

Modulation of fetal rat brain and liver phospholipid content by intraamniotic ethyl docosahexaenoate administration

In an attempt to elucidate the role of docosahexaenoic acid (DHA; 22:6n-3) in the developing brain, a method was devised whereby rapid enrichment of fetal brain and liver lipid with DHA was achieved. Fetal rats at 17 days of gestation were injected intraamniotically with ethyl docosahexaenoate (EtDHA). Control fetuses were administered ethyl oleate (EtOle). Brain lipid DHA content increased by almost 21% (p = 0.02) 3 days after EtDHA administration as compared with EtOle-injected fetuses, whereas liver lipid DHA content increased by almost 60% (p = 0.0002). At this time brain phosphatidylinositol content doubled, whereas phosphatidylserine (PS) content increased by > 50% (p = 0.03). Increases in liver PS (+25.8%; p = 0.015) and sphingomyelin (+43.6%; p = 0.01) content were observed. A redistribution of total brain phospholipid (PL) DHA was observed following EtDHA administration, resulting in a 56.4% increase in PS-DHA abundance (p < 0.05) and an 8.8% decrease in phosphatidylethanolamine-DHA abundance (p = 0.05). These results suggest modulation of fetal brain and liver PL and provide a method for enrichment of DHA content in discrete PLs during intrauterine life.

Molecular evolution of duplicate copies of genes encoding cytosolic glutamine synthetase in Pisum sativum

Here, we describe two nearly identical expressed genes for cytosolic glutamine synthetase (GS3A and GS3B) in Pisum sativum L. RFLP mapping data indicates that the GS3A and GS3B genes are separate loci located on different chromosomes. DNA sequencing of the GS3A and GS3B genes revealed that the coding regions are 99% identical with only simple nucleotide substitutions resulting in three amino acid differences. Surprisingly, the non-coding regions (5' non-coding leader, the 11 introns, and 3' non-coding tail) all showed a high degree of identity (96%). In these non-coding regions, 25% of the observed differences between the GS3A and GS3B genes were deletions or duplications. The single difference in the 3' non-coding regions of the GS3A and GS3B genes was a 25 bp duplication of an AU-rich element in the GS3B gene. As the GS3B mRNA accumulates to lower levels than the GS3A gene, we tested whether this sequence which resembles an mRNA instability determinant functioned as such in the context of the GS mRNA. Using the GS3B 3' tail as part of a chimeric gene in transgenic plants, we showed that this AU-rich sequence has little effect on transgene mRNA levels. To determine whether the GS3A/GS3B genes represent a recent duplication, we examined GS3-like genes in genomic DNA of ancient relatives of P. sativum. We observed that several members of the Viceae each contain two genomic DNA fragments homologous to the GS3B gene, suggesting that this is an ancient duplication event. Gene conversion has been invoked as a possible mechanism for maintaining the high level of nucleotide similarity found between GS3A and GS3B genes. Possible evolutionary reasons for the maintenance of these 'twin' GS genes in pea, and the general duplication of genes for cytosolic GS in all plant species are discussed.

Investigation of the factor VIII intron 22 repeated region (int22h) and the associated inversion junctions

A region of intron 22 of the factor VIII gene, which contains factor VIII-associated gene A (F8A), is repeated twice more nearer the Xq telomere. It has been proposed that intrachromosomal homologous recombination occurs between the intron 22 repeat and either of the two extragenic copies, resulting in the recurrent inversions that cause almost half of all cases of severe haemophilia A. We have precisely defined the repeated region as 9.5 kb of DNA which we have termed int22h (intron 22 homologous region). The junctions of the inversions examined were shown to represent precise exchanges between the int22h repeats, thus providing conclusive evidence for homologous recombination. The three copies of int22h were compared along 8 kb of their length, using chemical mismatch analysis, and found to be 99.9% similar. The presence of such long, almost identical inverted repeats near the Xq telomere could account for the high frequency at which the inversions occur.

Effects of dietary fat intervention on mental health in women

Several studies have identified potential detrimental sequelae of cholesterol and fat-lowering interventions in randomized trial. Little research has been published to document changes in mental health in women as a result of fat and cholesterol lowering interventions to prevent chronic disease. This paper examines the relationships among changes in dietary fat consumption and mental health in the Women's Health Trial, a randomized, controlled trial to determine whether lowering fat consumption to 20% of daily calories could reduce the incidence of breast cancer in women ages 45-69 years. Assessments were made at baseline and at the 12-month follow-up of several aspects of quality of life, including negative and positive affect and past, present, and future perceptions of health. Mental health variables were measured by the Mental Health Inventory, a standardized scale used in the Medical Outcomes study. Dietary intake was assessed for all subjects with the use of semiquantitative food frequency questionnaires. The change in mental health values (follow-up minus baseline) was significantly different between intervention and control groups for three of the four psychological variables: (a) anxiety; (b) depression; and (c) vigor. In all three cases, the direction of the change for intervention women was positive. Neither randomization assignment nor percent of calories from fat at the follow-up visit were significant predictors of mental health at the 1-year follow-up. Cholesterol changes were not related to levels of mental health variables in a sample of the women. These data indicate that lowering fat in the diets of healthy women does not produce overall lowering of any mental health variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiology and clinical spectrum of pneumococcal infections: an Israeli viewpoint

We performed a prospective study of consecutive pneumococcal infections documented during a six-month period in our clinical microbiology laboratory. A total of 59 cultures obtained from clinically significant specimens of 58 patients were positive for Streptococcus pneumoniae. Relative penicillin resistance occurred in 14 strains (24%) and only one (1.7%) was highly resistant to penicillin (minimum inhibitory concentration = 2.0 micrograms ml-1). Resistance to common alternative drugs was not found. Serotypes were of a wide variety, however types 1, 7 and 14 predominated (60% of all blood culture isolates). Twenty-three patients with community-acquired infection required hospitalization. Nosocomial pneumonia developed in three additional cases (14%). Invasive disease was diagnosed in 24 patients with pneumonia representing the most common infection (22 patients). Pneumonia was characterized by a high incidence of serious underlying diseases (82%) and associated bacteraemia (68%). Compared with controls, patients with penicillin-resistant pneumococcal pneumonia had a significantly higher incidence of previous hospitalizations and use of antibiotics (57 vs. 7%, P = 0.02). The overall case fatality rate was high (36%) and did not differ significantly between patients with pneumonia due to resistant and susceptible strains. The epidemiology and clinical spectrum of serious pneumococcal infections in Israel is similar to those described in many parts of the world, but high level resistance to penicillin and to other alternative drugs is still rare.

Genes galore: a summary of methods for accessing results from large-scale partial sequencing of anonymous Arabidopsis cDNA clones

High-throughput automated partial sequencing of anonymous cDNA clones provides a method to survey the repertoire of expressed genes from an organism. Comparison of the coding capacity of these expressed sequence tags (ESTs) with the sequences in the public data bases results in assignment of putative function to a significant proportion of the ESTs. Thus, the more than 13,400 plant ESTs that are currently available provide a new resource that will facilitate progress in many areas of plant biology. These opportunities are illustrated by a description of the results obtained from analysis of 1500 Arabidopsis ESTs from a cDNA library prepared from equal portions of poly(A+) mRNA from etiolated seedlings, roots, leaves, and flowering inflorescences. More than 900 different sequences were represented, 32% of which showed significant nucleotide or deduced amino acid sequences similarity to previously characterized genes or proteins from a wide range of organisms. At least 165 of the clones had significant deduced amino acid sequence homology to proteins or gene products that have not been previously characterized from higher plants. A summary of methods for accessing the information and materials generated by the Arabidopsis cDNA sequencing project is provided.

Two inhibitors of pro-inflammatory cytokine release, interleukin-10 and interleukin-4, have contrasting effects on release of soluble p75 tumor necrosis factor receptor by cultured monocytes

The biological activity of the pro-inflammatory cytokine, tumor necrosis factor (TNF)-alpha depends on the level of TNF-alpha itself, the expression of the p55 and p75 cell surface receptors for TNF on target cells and the concentrations of the natural inhibitors of TNF-alpha, the soluble p55 and p75 TNF receptors (TNF-R). Interleukin (IL)-10 and IL-4 are known to inhibit TNF-alpha production by monocytes. We, therefore, investigated the effects of IL-10 and IL-4 on the cell surface expression and release of TNF-R by human monocytes to determine whether these cytokines also indirectly modulated the biological activity of TNF-alpha. Exposure to IL-10 (1-10 U/ml) for 24 or 48 h increased soluble p75 TNF-R expression and concomitantly reduced surface expression of p75 TNF-R. Further, IL-1 alpha-stimulated production of TNF-alpha was diminished by IL-10 and only a small proportion of this TNF-alpha was bioactive, consistent with increased production of inhibitory soluble TNF-R. IL-10 also induced down-regulation of surface p55 TNF-R on monocytes, and increased release of soluble p55 TNF-R. However, the expression of soluble p55 TNF-R was much lower than soluble p75 TNF-R, indicating that it contributed less importantly to neutralization of TNF-alpha under these conditions. Like IL-10, IL-4 supressed the release of TNF-alpha by monocytes. In contrast to IL-10, however, IL-4 (0.1-10 ng/ml) supressed the release of soluble p75 TNF-R from monocytes in a dose-dependent manner. Release of soluble p55 TNF-R was also supressed by IL-4. IL-10, therefore, reduces the pro-inflammatory potential of TNF in three ways: by down-regulating surface TNF-R expression whilst increasing production of soluble TNF-R and inhibiting the release of TNF-alpha itself. This suggests that IL-10 may be useful in the treatment of diseases where overexpression of TNF-alpha occurs.

AIDS-related cholangiopancreatographic changes

The cholangiographic and pancreatographic appearances of the acquired immunodeficiency syndrome (AIDS) associated cholangitis were evaluated in 26 patients. Twenty-four patients were diagnosed by retrograde cholangiography or endoscopic cholangiopancreatography (ERC or ERCP). One patient was diagnosed by T-tube cholangiography and another patient by transhepatic cholangiography. The radiographic findings ranged from intrahepatic ductal abnormalities with or without involvement of the extrahepatic biliary tree (eight patients) to irregularities and strictures involving the ampulla of Vater or the intrapancreatic portion of the common bile duct (CBD) with proximal dilatation (18 patients). Significant strictures involving the juxta-ampullary pancreatic duct were identified in six of 12 patients. Twenty-one of the 26 patients had associated infections which included: Cryptosporidium (CS), Mycobacterium avium intracellulare (MAI), cytomegalovirus (CMV), Microsporidium (MSP), and Isospora (ISP). Three patients were operated upon for acute acalculous cholecystitis. In each instance, organisms were identified in both the bile duct and the inflamed gallbladder.

Detecting patterns in protein sequences

The detection of conserved sequence patterns (motifs) in related proteins often yields valuable structural and functional insights. We describe a method that utilizes rigorous statistics and a depth-first search procedure to efficiently and exhaustively search a set of proteins for significant patterns up to a specified length. Additional procedures classify related patterns into groups and identify protein segments most likely to share a common motif. The utility of the method was demonstrated on several difficult test problems; detection of motifs among 56 proteins in the acyltransferase family, detection of a dinucleotide-binding fold present within a small subset of a set of 91 distantly related and unrelated proteins, detection of the helix-turn-helix motif in 15 distantly related proteins and detection of subtle internal repeats in a prenyltransferase. In a search of a large set of sequences for internal repeats, the method detected novel ankyrin-like repeats in an Escherichia coli protein.

Protection against turkey rhinotracheitis pneumovirus (TRTV) induced by a fowlpox virus recombinant expressing the TRTV fusion glycoprotein (F)

A recombinant fowlpox virus was produced which expressed the fusion protein (F) of turkey rhinotracheitis virus (TRTV), a pneumovirus. Turkey poults were vaccinated twice, at an interval of 2 weeks, intramuscularly and by wing web on each occasion, with the recombinant or a control fowlpox virus. Two weeks after the second vaccination the poults were challenged superconjunctivally and intranasally with virulent TRTV. A partially protective immune response was achieved; turkeys vaccinated with the F recombinant showed milder clinical signs and 1000-fold less challenge virus was recovered from the nose and trachea compared with turkeys that had been vaccinated with control fowlpox virus. Expression of the F protein induced antibodies which were detectable both by an ELISA and a virus neutralization test. These results show that the immune responses to the F protein play a major role in protection against TRTV and indicate that recombinant viruses expressing the TRTV F protein have potential as vaccines against TRT.

VP2 sequences of recent European 'very virulent' isolates of infectious bursal disease virus are closely related to each other but are distinct from those of 'classical' strains

Part of genomic segment A of five recent European 'very virulent' (VV) isolates of infectious bursal disease virus, encoding the major, conformational, protective epitope, have been reverse-transcribed, amplified and cloned. Sequence analysis of 582 bases of VP2 showed that the four U.K. isolates are closely related to each other, differing by no more than two bases, but are distinct from the 'classical' type 1 strains (differing by at least 29 bases, or four amino acids, from any other strain and by 15 bases, or three amino acids, from the consensus sequence of all other strains). The U.K. isolates differ from an earlier VV isolate from the Netherlands by no more than five bases or two amino acids. The U.K. isolates differ by only one or two bases, with no amino acid changes, from the recently published sequence of a Japanese VV isolate.

Fisher's method of scoring in statistical image reconstruction: comparison of Jacobi and Gauss-Seidel iterative schemes

Many algorithms for medical image reconstruction adopt versions of the expectation-maximization (EM) algorithm. In this approach, parameter estimates are obtained which maximize a complete data likelihood or penalized likelihood, in each iteration. Implicitly (and sometimes explicitly) penalized algorithms require smoothing of the current reconstruction in the image domain as part of their iteration scheme. In this paper, we discuss alternatives to EM which adapt Fisher's method of scoring (FS) and other methods for direct maximization of the incomplete data likelihood. Jacobi and Gauss-Seidel methods for non-linear optimization provide efficient algorithms applying FS in tomography. One approach uses smoothed projection data in its iterations. We investigate the convergence of Jacobi and Gauss-Seidel algorithms with clinical tomographic projection data.

Legionellaceae in the potable water of Nova Scotia hospitals and Halifax residences

Water was cultured from 39 of 48 hospitals (7 Halifax hospitals and 32 non-Halifax hospitals) in the province of Nova Scotia and from 90 residences (74 private dwellings, 16 apartments) in Halifax to determine the frequency of legionella contamination. Six of seven Halifax hospitals had Legionellaceae isolated from their potable water compared with 3 of 32 non-Halifax hospitals (P < 0.0001). Overall, 19 of 59 (32%) of the water samples from Halifax hospitals were positive for legionellae compared with 5 of 480 (1%) samples from non-Halifax hospitals (P < 0.0000). Five of the six positive Halifax hospitals had Legionella pneumophila serogroup 1 and 1 had L. longbeachae serogroup 2 recovered from their potable water. Legionella contamination was associated with older, larger (> or = 50 beds) hospitals with total system recirculation. These hospitals also had water with a higher pH and calcium content but lower sodium, potassium, nitrate, iron and copper content. Fourteen of the 225 (6.2%) water samples from Halifax residences were positive for legionellae -8% (6/74) of the single family dwellings were positive, compared with 25% (4/16) apartments. The positivity rate of 15.7% for the 19 electric hot-water heaters in Halifax homes was not significantly different from the 32% positivity for Halifax hospitals. L. longbeachae accounted for 2 of the 14 isolates of legionellae from Halifax homes.

The clinical ladder. Impact on nurse satisfaction and turnover

Nurse administrators have advocated clinical ladder programs to address salary compression of experienced nurses. However, few clinical ladder programs have survived the test of time. One possible explanation for the demise of these programs is the failure to assess nurses' satisfaction with clinical ladder programs. Ongoing assessment of these programs may provide a solution to early demise.