Oscillation in resting tension of chick skeletal muscle treated with toxin V from scorpion venom, reduced [calcium]o and cadmium

1. An oscillation in resting tension of the chick biventer cervicis muscle is induced by scorpion toxin (CsT-V), reduced [Ca]o and by Cd2+. Other chick muscles, e.g. semispinalis cervicis, anterior and posterior latissimus dorsi, also oscillate with the same treatments. The period of the oscillation in the biventer cervicis muscle is uniform, averaging 5-6 min. 2. The oscillation and the period are very sensitive to changes in temperature, [Ca]o, [K]o, ouabain and tetrodotoxin [TTX]. The oscillation is resistant to twitch blocking dosages of nicotinic antagonists. 3. The period of the oscillation varies inversely as the temperature (26-37 degrees C), log [K]o and [ouabain] and directly as the log [Ca]o and [TTX]. 4. These data support the inference that the oscillator is postjunctional and results from fluctuation in the electrochemical gradient of ions across the muscle cell membrane. The role, if any, of the Na+, K+ pump in the primary oscillogenic mechanism is not evident from our data.     

GH assessment and three years' hGH therapy in girls with Turner syndrome.

Fifteen girls with Turner syndrome (TS) were submitted to GH secretion assessment before undergoing hGH therapy. In the first 9 months, hGH was given at a dose of 0.5 IU/kg/week s.c. daily; afterward, the dose was increased to 1 IU/kg/week s.c. daily. The girls were prepubertal, with a mean (SD) chronological age (CA) of 12.5 (2.6) years, and a mean (SD) bone age of 10.5 (1.8) years. A clonidine stimulation test, 1-29 GHRH test and GH spontaneous nocturnal secretion assessment were performed in all patients. Results showed a variable pattern of GH secretion in 10 patients, in only 2 did we find all values definitely normal, and in 3 we found a total GH deficiency. Height velocity, expressed as standard deviation scores (SDS) for CA according to Turner references, during the first year of treatment increased significantly: 0.36 (1.15) -3.30 (2.87) (p < 0.001), and the increment remained quite unchanged during both the second and third years: 3.16 (2.96) and 2.55 (3.87), respectively (n.s.). Height, expressed in SDS for CA for Turner references, increased significantly throughout the whole period of treatment and reached the highest value at the end of the third year of therapy. GH secretion parameters poorly correlated with pretreatment auxological data or response to treatment. Our long-term study confirms that in TS GH measurement is not useful in indicating hGH therapy or in predicting the response.     

Ion channels in plants: From bioelectricity,via signaling,to behavioral actions

In his recent opus magnum review paper published in the October issue of Physiology Reviews, Rainer Hedrich summarized the field of plant ion channels.¹ He started from the earliest electric recordings initiated by Charles Darwin of carnivorous Dionaea muscipula,^1,2 known as Venus flytrap, and covered the topic extensively up to the most recent discoveries on Shaker-type potassium channels, anion channels of SLAC/SLAH families, and ligand-activated channels of glutamate receptor-like type (GLR) and cyclic nucleotide-gated channels (CNGC).¹     

C15, C20, and C25 isoprenoid homologues in glycerol diether phospholipids of methanogenic archaebacteria

The glycerol diether phospholipids of 25 monocultures of methanogenic bacteria were isolated and degraded with hydriodic acid. The resulting alkyl iodides were converted to acetate esters and alcohols which were examined using capillary gas-liquid chromatography. The presence of C20 phytanol was observed in accordance with previous studies. Soft fragmentation by chemical ionization mass spectrometry combined with selected ion monitoring enabled the detection, for the first time, of C15 and C25 isoprenologues as components of the diether phospholipids in several strains.     

A sensitive routine assay for urinary albumin based on the competitive binding to anti-albumin antibodies in solid phase

The detection of microalbuminuria has a high prognostic value in diabetic patients with no symptoms of clinical nephropathy. Attention has been focused on the development of a simple, reproducible, specific, and, above all, sensitive method to detect albuminuria in the urine. The method is based on the competitive binding between albumin in the urine to be tested and a fixed amount of radiolabelled albumin to anti-albumin immunoglobulins in solid phase. The immunoglobulin C fraction of a rabbit anti-human albumin antiserum was left to coat highly adsorbent polystyrene microtitre tubes. While the aspecific tube binding was overcome by saturation with a solution of gelatine, increasing dilutions of standard albumin or the diluted urine samples to be tested were left to incubate with an equal volume of radiolabelled albumin at room temperature for 1 hour. The cold/hot albumin mixture was added to anti-albumin immunoglobulin-coated tubes, which had been repeatedly washed, and left to incubate. After washing, radioactivity was assessed. This assay has proved to be fast, simple and highly sensitive since it detects up to 25 ng of albumin per ml and is of value in large-scale screening for microalbuminuria in diabetic patients.     

Neurokinin Receptors Could Be Differentiated by Their Capacity to Respond to the Transglutaminase-Synthesized γ-(Glutamyl5)Spermine Derivative of Substance P

Abstract: Four different γ-(glutamyl⁵)amine derivatives of substance P (SP) were synthesized in vitro in the presence of purified guinea pig liver transglutaminase and Ca²⁺. The 1,3-diaminopropane, spermidine, spermine (Spm), and monodansylcadaverine adducts of the neuropeptide were purified by HPLC on a reversed-phase column and characterized by fast atom bombardment mass spectrometry. The γ-(glutamyl⁵)Spm derivative of SP (Spm-SP) was found to be able, like the parent neuropeptide, to provoke rabbit aorta relaxation, to decrease rat arterial blood pressure, and to inhibit collagen-induced platelet aggregation. Unlike SP, only a weak inflammatory response was observed when Spm-SP was injected in the rat hind limb. All these effects were found to be prevented by N ^ω-nitro- l -arginine methyl ester, a well-known nitric oxide synthesis inhibitor. In contrast, Spm-SP was completely ineffective in contracting guinea pig ileal segments, thus confirming our preliminary observations indicating that Spm-SP does not evoke SP-like spasmogenic effects on isolated smooth muscle preparations. The specificity of the effects due to the selective introduction of a Spm moiety at the glutamine⁵ level was demonstrated by the SP agonist pharmacological profile of the other γ-(glutamyl⁵)amine derivatives tested. These results suggest that neurokinin receptors could be differentiated by their capacity to respond to Spm-SP.     

Effect of luteal metoclopramide-induced hyperprolactinemia on pituitary and luteal responsiveness to gonadotropin-releasing hormone

The pituitary and corpus luteum responses to acute gonadotropin-releasing hormone (GnRH) administration at the mid-luteal phase (LP) were studied in 24 infertile women. Patients were randomly divided into two groups. In one group (n = 12) metoclopramide (MCP, 10 mg orally 3 times daily) was administered from day 0 or 1 of the LP for 7 days. On day 7 or 8 of LP blood samples were taken every 15 min for 180 min; then 25 micrograms GnRH were acutely administered intravenously and blood samples taken at 185, 195, 210, 225, 240, 255, 270, 285 and 300 min. In the other 12 patients the same experimental design was performed on day 7 or 8 of an untreated LP. Plasma prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone and estradiol (E2) were assayed. The responsiveness of the different hormones to GnRH was evaluated as the integrated secretory area for 120 min after injection (sISA = stimulated integrated secretory area) and as the percentage increase (delta A) with respect to the area under basal conditions before GnRH administration (bISA = basal integrated secretory area). MCP-treated women showed higher basal PRL levels (p less than 0.01) and lower basal plasma concentrations and bISA (p less than 0.01) values of LH than controls. After GnRH a more marked response of LH secretion was observed in the treated group (p less than 0.01), so that the absolute values of sISA were superimposable in both groups. Basal and stimulated FSH secretion did not differ significantly in the study groups. Basal plasma and bISA values of progesterone were also decreased in MCP-treated subjects. After GnRH injection the absolute values of progesterone sISA were greater in controls (p less than 0.01), but delta A values were similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Oxygen and carbon isotope variations in Chamelea gallina shells: Environmental influences and vital effects

Stable isotopes in mollusc shells, together with variable growth rates and other geochemical properties, can register different environmental clues, including seawater temperature, salinity and primary productivity. However, the strict biological control over the construction of biominerals exerted by many calcifying organisms can constrain the use of these organisms for paleoenvironmental reconstructions. Biologically controlled calcification is responsible for the so called vital effects that cause a departure from isotopic equilibrium during shell formation, resulting in lower shell oxygen and carbon compared to the equilibrium value. We investigated shell oxygen and carbon isotopic composition of the bivalve Chamelea gallina in six sites along with a latitudinal gradient on the Adriatic Sea (NE Mediterranean Sea). Seawater δ¹⁸O and δ¹³C_DIC varied from North to South, reflecting variations in seawater temperature, salinity, and chlorophyll concentration among sites. Shell δ¹⁸O and δ¹³C differed among sites and exhibited a wide range of values along with the ~400 km latitudinal gradient, away from isotopic equilibrium for both isotopes. These results hampered the utilization of this bivalve as a proxy for environmental reconstructions, in spite of C. gallina showing promise as a warm temperature proxy. Rigorous calibration studies with a precise insight of environment and shell growth are crucial prior to considering this bivalve as a reliable paleoclimatic archive.