MYELOGRAPHY—Diagnostic Value in Lesions of the Lumbar Intervertebral Discs with a Variation in Technique

Myelography using pantopaque in greater than usual amount with a variation in technique, which is described, is believed to provide increased accuracy in differential diagnosis and precise localization of lesions in the lumbar spine. The need for multiple space exploration is eliminated and more detailed information concerning the size and shape of lesions is provided as compared to that secured by the use of 3 or 6 cc. of opaque medium and fluoroscopic examination alone. In 53 cases in which lumbar myelography was performed and the diagnosis verified or disproved at operation, there was a 5 per cent diagnostic error in 41 instances in which the method outlined was used, as compared with 17 per cent error in 12 cases in which only 3 or 6 cc. of radiopaque material and fluoroscopy alone were used. The accuracy of the procedure would appear to warrant its use in the evaluation of patients suspected of having abnormalities of the lumbar discs associated with nerve root compression.     

Synthesis and intracellular transport of protein by the colleterial gland of the cecropia silkmoth

The tubular portion of the colleterial gland of the cecropia silkmoth secretes protein which labels extensively with glycine and appears as a single peak when separated by acrylamide gel electrophoresis. The radioactive peak does not stain with protein stains or absorb at 280 nm, but is dispersed by Pronase digestion. Synthesis of the peak is sensitive to inhibition by puromycin and cycloheximide but is not sensitive to actinomycin or chloramphenicol inhibition. Amino acid analysis revealed a composition of 30% glycine, 33% aspartic acid, and insignificant amounts of aromatic amino acids; the molecular weight was calculated to be 160,000. Autoradiographic analysis revealed that nearly all the glycine incorporated is transported from the mature secretory cells, and the half-time of secretion is calculated to be 3.4 hr. The possible use of this product as a marker for biochemical differentiation is discussed.     

In situ hybridization of semithin Epon sections with BrdU labelled oligonucleotide probes

Summary We recently described a nonradioactive method for in situ hybridization with 5-bromo-2-deoxyuridine (BrdU) labelled oligonucleotide probes. An antibody to BrdU and immunocytochemistry were used in order to detect the hybridization signal. We have now applied this method to semithin Epon sections, in order to hybridize consecutive sections through single cells with different probes and to stain them with antibodies to neuropeptides. It could be shown that Epon embedding preserves mRNA well. In the present study we used a BrdU labelled synthetic oligonucleotide probe complementary to a fragment of the vasopressin precursor and an antibody to Arg-vasopressin. Vasopressin mRNA was demonstrable in a fraction of the vasopressin immunoreactive neurons in the magnocellular nuclei. In addition some of the magnocellular neurons showed either hybridization or vasopressin immunostaining only, perhaps indicating different stages of synthetic and secretory activity. The method described seems to be a valuable tool for studying synthetic activity in peptidergic neurons on a single cell level. The method might also have potential for in situ hybridization on the electronmicroscopical level.     

A ‘Problematic fossil’ revealed:Pycnoporidium ? eomesozoicum Flügel, 1972 (Late Triassic,Tethys)—not an enigmatic alga but a strophomenid brachiopod (Gosaukammerella n.g.)

Summary The microproblematicumPycnoporidium ? eomesozoicum Flügel, 1972, from Upper Triassic reefs of the Alpine-Mediterranean region, Turkey Oman and Iran (originally interpreted as possible alga) represents the type species of a new strophomenid brachiopod genus (Gosaukammerella n.g.). The genus is characterized by a very small, millimeter-sized plano-convex shell, whose ventral valve is attached to the substratum (mainly sponges) by symmetrically arranged outgrowths developing from a pseudopunctate, lamellose foliated shell wall and composed of densely spaced subparallel ‘tubes’ comparable with productide spines secreted by papillose extensions of the mantle.Gosaukammerella seems to be the only reliable candidate for the existence of post-Paleozoic strophomenid (productid ?) brachiopods. Gosaukammerella eomesozoica is restricted to possibly cryptic, shaded reef environments inhabited predominantly by sponges serving as substrates for micromorphic brachiopods.     

Developmental control of xylem hydraulic resistances and vulnerability to embolism in Fraxinus excelsior L.: impacts on water relations

The freezing tolerance of many plants, such as pea (Pisum sativum),is increased by exposure to low temperature or abscisic acidtreatment, although the physiological basis of this phenomenonis poorly understood. The freezing tolerance of pea shoot tips,root tips, and epicotyl tissue was tested after cold acclimationat 2C, dehydration/rehydration, applications of 10^–4M abscisic acid (ABA), and deacclimation at 25C. Tests wereconducted using the cultivar ‘Alaska’, an ABA-deficientmutant ‘wil’, and its ‘wildtype’. Freezinginjury was determined graphically as the temperature that caused50% injury (T₅₀) from electrical conductivity. Endogenous ABAwas measured using an indirect enzyme-linked immunosorbant assay,and novel proteins were detected using 2-dimensional polyacrylamidegel electrophoresis. The maximum decrease in T₅₀ for root tissuewas 1C for all genotypes, regardless of treatment. For ‘Alaska’shoot tips and epicotyl tissue, exogenous ABA increased thefreezing tolerance by –1.5 to –4.0C, while coldtreatment increased the freezing tolerance by –7.5 to–14.8C. Cold treatment increased the freezing toleranceof shoot tips by –9 and –15C for ‘wil’and ‘wild-type’, respectively. Cold acclimationincreased endogenous ABA concentrations in ‘Alaska’shoot tips and epicotyls 3- to 4-fold. Immunogold labeling increasednoticeably in the nucleus and cytoplasm of the epicotyl after7 d at 2C and was greatest after 30 d at the time of maximumfreezing tolerance and soluble ABA concentration. Cold treatmentinduced the production of seven, three, and two proteins inshoot, epicotyl, and root tissue of ‘Alaska’, respectively.In ‘Alaska’ shoot tissue, five out of seven novelproteins accumulated in response to both ABA and cold treatment.However, only a 24 kDa protein was produced in ‘wil’and ‘wild-type’ shoot and epicotyl tissues aftercold treatment. Abscisic acid and cold treatment additivelyincreased the freezing tolerance of pea epicotyl and shoot tissuesthrough apparently independent mechanisms that both resultedin the production of a 24 kDa protein. Key words: Pisum sativum, cold acclimation, immuno-localization     

N-Acetylaspartylglutamate Stimulates Metabotropic Glutamate Receptor 3 to Regulate Expression of the GABAAα6 Subunit in Cerebellar Granule Cells

Abstract: We have shown that the vertebrate neuropeptide N-acetylaspartylglutamate (NAAG) meets the criteria for a neurotransmitter, including function as a selective metabotropic glutamate receptor (mGluR) 3 agonist. Short-term treatment of cerebellar granule cells with NAAG (30 µM) results in the transient increase in content of GABA_Aα6 subunit mRNA. Using quantitative PCR, this increase was determined to be up to 170% of control values. Similar effects are seen following treatment with trans-1-aminocyclopentane-1,3-dicarboxylate and glutamate and are blocked by the mGluR antagonists (2S,3S,4S)-2-methyl-2-(carboxycyclopropyl)glycine and (2S)-α-ethylglutamic acid. The effect is pertussis toxin-sensitive. The increase in α6 subunit mRNA level can be simulated by activation of other receptors negatively linked to adenylate cyclase activity, such as adenosine A1, α2-adrenergic, muscarinic, and GABA_B receptors. Forskolin stimulation of cyclic AMP (cAMP) levels abolished the effect of NAAG. The change in α6 levels induced by 30 µM NAAG can be inhibited in a dose-dependent manner by simultaneous application of increasing doses of the β-adrenergic receptor agonist isoproterenol. The increase in α6 mRNA content is followed by a fourfold increase in α6 protein level 6 h posttreatment. Under voltage-clamped conditions, NAAG-treated granule cells demonstrate an increase in the furosemide-induced inhibition of GABA-gated currents in a concentration-dependent manner, indicating an increase in functional α6-containing GABA_A receptors. These data support the hypothesis that NAAG, acting through mGluR3, regulates expression of the GABA_Aα6 subunit via a cAMP-mediated pathway and that cAMP-coupled receptors for other neurotransmitters may similarly influence GABA_A receptor subunit composition.