Antibody production and Escherichia coli resistance in socially stable flocks of dwarf and nondwarf chickens

Dwarf and normal pullets from lines that had undergone selection for divergence in juvenile body weight were maintained in cages as socially stable flocks. Antibody titers were measured at 6 and 14 weeks of age and an Escherichia coli challenge was administered at 16 weeks of age. There was a significant line by dwarf genotype interaction with dwarfs having lower antibody titers than normal pullets in the low weight line and higher antibody titers in the high weight line. The mortality of dwarfs from the low weight line to an Escherichia coli challenge was much higher than that of any other group. These results were consistent with those from previous experiments where the Escherichia coli challenge was given to hens in single cages.     

Three primitive reflexes in HIV-1-infected individuals: a possible clinical marker of early central nervous system involvement

We studied one hundred and six neurologically asymptomatic HIV-1-seropositive patients, mostly drug abusers, in various stages of HIV-1 infection to evaluate the frequency of three primitive reflexes: snout, palmomental, and glabellar. We also examined one hundred HIV-1-seronegative drug abusers and one hundred healthy heterosexual individuals. We observed the presence of one or more primitive reflexes in 41% of HIV-1-seropositive subjects, in 8% of HIV-1-seronegative drug abusers and in 3% of healthy individuals. We elicited more than one primitive reflex in 22% of patients, but never among the subjects of the two control groups. The associations of multiple reflexes were significantly more frequent in the most severe CDC stages. Our observations suggest that including evaluation of primitive reflexes in a standard neurologic examination may be useful in screening for early non specific cerebral dysfunction in neurologically asymptomatic HIV-1-seropositive subjects.     

Hemin: levels in experimental subarachnoid hematoma and effects on dissociated vascular smooth-muscle cells

Although hemin is known to exert toxic effects on a variety of cell types, its possible participation in the genesis of cerebral vasospasm has received little attention. The authors measured the concentration of hemin in experimental subarachnoid clot and studied its effects on the morphology and 45Ca++ uptake of vascular smooth-muscle cells dissociated from canine carotid artery. Craniectomies were performed in five dogs under general anesthesia, and 3 to 5 ml of autologous whole blood was deposited in the supraclinoid subarachnoid compartment. The concentration of hemin recovered by Folch extraction from clotted material removed 7 days after surgery was 390 +/- 247 microM (mean +/- standard error of the mean). Mean vascular smooth-muscle cell length after 40 minutes of exposure to 50 microM hemin was 37.3 +/- 1.2 microns (control 51.6 +/- 1.6 microns) (p < 0.01). The mean percent permeation of 45Ca++, measured by a dual label technique, of cells exposed to hemin was 200.9% +/- 23% (control 102.9% +/- 4.3%) (p < 0.01). These findings indicate that hemin accrues in subarachnoid hematoma, that it exerts a constrictive effect on vascular smooth-muscle cells, and that this effect is associated with an increased uptake of Ca++. This study demonstrates that hemin should be included in the list of potential agents that participate in the development of cerebral vasospasm.     

A modified cell surface marker gene for transgenic animal studies

We developed a marker gene encoding a human cell surface molecule called CD8 for use in transgenic animal studies. The CD8 cDNA contains three mutations: one in the extracellular domain which prevents interaction with its ligand MHC class I and the other two in the cytoplasmic domain which inhibit its signalling function. The cDNA was linked to a fragment of the human growth hormone gene and in transgenic animal studies, expression was observed in the appropriate cell types using a CD2 enhancer. The advantage of the CD8 marker gene is that it is incapable of signalling via its only known signalling pathway and its expression can be monitored using monoclonal antibodies and microscopy or flow cytometry.     

In vitro cross-resistance and collateral sensitivity in seven resistant small-cell lung cancer cell lines: preclinical identification of suitable drug partners to taxotere, taxol, topotecan and gemcitabin

The thiazole orange dye 1,1'-(4,4,8,8-tetramethyl-4,8-diazaundecamethylene)-bis[4-[3-methy l-2, 3-dihydro(benzo-1,3-thiazole)-2-methylidene]]quinolinium tetraiodide (TOTO) binds to double-stranded DNA (dsDNA) in a sequence selective bisintercalation. Each chromophore is sandwiched between two base pairs in a (5'-CpT-3'):(5'-ApG-3') site, and the linker spans over two base pairs in the minor groove. The binding of analogs of TOTO in which the linker has been modified is examined. The aim of the study is to utilize the sequence selectivity of the TOTO chromophores to enhance and/or alter the overall selectivity of the binding. One- and two-dimensional 1H-NMR investigations of complexes between TOTO analogs and various dsDNA oligonucleotides are reported. The following analogs were synthesized and used: 1,1'-(4,4,8,8-tetramethyl-4,8-diazadodecamethylene) -bis[4-[3-methyl-2,3-dihydro- (benzo-1,3-thiazole)-2-methylidene]]quinolinium tetraiodide (TOTO10), 1,1'-(5,5,9,9-tetramethyl-5,9-diazatridecamethylene)-bis[4-[3-meth yl-2, 3-dihydro(benzo-1,3-thiazole)-2-methylidene]]quinolinium tetraiodide (TOTO11), and 1,1'-(6,6,10,10-tetramethyl-6,10-diazapentadecamethylene)-bis[4-[3 -methyl-2, 3-dihydro(benzo-1,3-thiazole)-2-methylidene]]quinolinium tetraiodide (TOTO13). The results show that with a longer linker the dyes can bisintercalate into two (5'-CpT-3'):(5'-ApG-3') sites separated by one or two base pairs. Bisintercalation in two such "isolated" binding sites yields non-nearest-neighbor bisintercalation in which the linker spans over more than two base pairs. The investigations also showed that an exact length of the linker is not crucial for the site selectivity since TOTO, TOTO10, and TOTO11 are almost equally suitable in binding selectively to the (5'CTAG-3')2 sequence. Fluorescence measurements show that TOTO10, TOTO11, and TOTO13 have higher fluorescence quantum yields than TOTO when bound to d(CGCTAGCG)2. This indicates that the length of the linker in TOTO may not be the optimum one in terms of using the dye as a fluorescence marker.     

Identification and characterisation of a human calmodulin-stimulated phosphodiesterase PDE1B1

A cDNA encoding a calmodulin-stimulated 3',5'-cyclic nucleotide phosphodiesterase (PDE) was isolated from a human brain cDNA library. The cDNA, designated HSPDE1B1, encoded a protein of 536 amino acids that shared 96% sequence identity with the bovine "63 kDa" calmodulin-stimulated PDE. The recombinant protein had cyclic nucleotide phosphodiesterase activity that was stimulated approximately 2-fold by Ca2+/calmodulin and preferred cGMP as substrate. In addition, the enzymatic activity of HSPDE1B1 was inhibited by phosphodiesterase inhibitors with potencies similar to that displayed toward the bovine PDE1 enzymes: IBMX approximately equal to 8-methoxymethyl-IBMX > vinpocetine approximately equal to zaprinast > cilostamide > rolipram. HSPDE1B1 mRNA was found predominantly in the brain. Lower mRNA levels were found in heart and skeletal muscle. In situ hybridisation of brain revealed expression of HSPDE1B1 predominately in neuronal cells of the cerebellum, hippocampus and caudate. The HSPDE1B1 gene was mapped to human chromosome 12. A partial genomic sequence of HSPDE1B1 was isolated and shown to contain two splice junctions that are conserved in the rat PDE4 and the Drosophila dunce genes.