Purification and partial characterization of rat kidney histamine-N-methyltransferase

Histamine-N-methyltransferase (EC 2.1.1.8) was purified 1700-fold with a yield of 9% from rat kidney. Purification included ammonium sulfate precipitation, linear gradient DEAE-cellulose chromotography and S-adenosylhomocysteine affinity chromotography. The purified enzyme preparation showed a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a molecular weight of 35 000. The isoelectric point of the enzyme was at pH 5.2. The purified enzyme preparation did not contain detectable amounts of histamine. The purified enzyme was totally inhibited in 100 μM parahydroxymercuric benzoate and in 10 μM iodoacetamide, and it was found to be stabilized with dithiothreitol (1 mM), suggesting that the enzyme has an SH-group in the active center. The K_m values for histamine and S-adenosylmethionine were 6.0 and 7.1 μM, respectively. 50% inhibition of histamine-N-methyltransferase was obtained at 28 μM S-adenosylhomocysteine and 100 μM methylhistamine. The purified enzyme was slightly inhibited in 1 mM methylthioadenosine. Histamine in concentrations higher than 25 μM caused substrate inhibition.     

Effect of ten different target tissues on nerve fibre outgrowth from rat sympathetic ganglia in organotypic co-cultures

Sympathetic thoracic chain ganglia of 3-day-old rats were cultured in collagen gel medium for 24 hours together with explants from heart atrium, liver, kidney, cornea, iris, lung, adrenal cortex, adrenal medulla, skeletal muscle, or vas deferens. The extent of nerve fibre growth was estimated by counting the number of fibres crossing each arc of a sector drawn in the ocular. The various tissues stimulated nerve fibre growth to distinctly different extents. The increase in the nerve fibre outgrowth induced by atrium and iris was statistically highly significant. Kidney, liver, vas deferens, lung, and adrenal cortex had, in that order, a decreasingly stimulatory influence on sympathetic chain ganglia. Yet they all caused a significant increase in nerve fibre growth. Skeletal muscle, cornea and adrenal medulla had no stimulatory effect. Since the significant effects of the tissue explants were abolished by antiserum to nerve growth factor (NGF), it is concluded that the observed effects were due to NGF produced by the explants. The only exception was vas deferens, the stimulatory action of which proved to be partially NGF-independent.     

Isolation, purification, and partial chemical characterization of chromium(III) fractions existing in brewer's yeast and Sabouraud's liquid medium.

An ethanol extract of brewer's yeast which had been cultivated in a medium containing trivalent 51Cr was analyzed for 51Cr compounds by using petroleum ether extraction, gel filtration, cation and anion exchange chromatography and thin layer chromatography. Similar analytical procedures as for the above analysis were used for studying 51Cr compounds formed in the spent culture medium and in a sterile medium. Several 51Cr fractions were isolated from the three chromium sources, but one anionic 51Cr fraction present in the yeast and in the spent culture medium was not found in the sterile medium. Molecular weight estimations of the 51Cr fractions by gel filtration chromatography showed that the 51Cr ion exchange fractions contained several 51Cr compounds. The molecular weights of these compounds ranged from 150 to 1000 daltons and the molecular weights of 51Cr compounds separated from the yeast were markedly lower than those of the corresponding ion exchange fractions isolated from the culture medium. By using thin layer chromatography it was possible to isolate 51Cr compounds from the main bulk of ninhydrin active impurities. The polarity of all 51Cr compounds was found to be greater than that of most amino acids. The 51Cr compounds isolated from the yeast were mixed with 125I-insulin and incubated, after which the solution was eluted through Sephadex G-50 gel to test if binding had occurred. Elution peaks of 51Cr and 125I-insulin showed that 51Cr compounds were not bound to the insulin.     

Effects of low frequency electric fields on the sedimentation rate of human blood. Preliminary observations

The erythrocyte sedimentation rate (ESR) of human blood samples exposed to electric fields at frequencies ranging from 1 Hz to 100 kHz was measured. Statistically significant differences in ESR were found between the exposed and the control samples at most of the frequencies used. The results suggest a possible nonlinear dependence of the effect on frequency, the threshold field strength varying from about 25 V/m to about 5 kV/m.     

Effects of 100-Hz magnetic fields with various waveforms on the development of chick embryos

Summary Chick embroys were exposed during their 52 first hours of development to 100-Hz magnetic fields. Sinusoidal, square and pulsed waveforms were used at average field strengths from 0.1 A/m to 80 A/m. After exposure, the embryos were examined for abnormalities and classified by the developmental stages. When bipolar oscillations (oscillating at both sides of the zero-level) were used, the percentage of abnormal embryos was significantly increased above 1 A/m. In exposure to unipolar square waves, no significant effect on the percentage of abnormalities could be demonstrated. The developmental stage was possibly affected by unipolar square waves at 0.1 A/m, all other field strengths and wave-forms being apparently ineffective.     

Generation of cell-mediated cytotoxicity against bovine-papilloma-virus-transformed primary mouse cell lines

Summary The immunogenicity and immunosensitivity of primary mouse cell lines transformed by bovine papilloma virus 1 (BPV1) DNA were studied in a syngeneic mouse model by determining cell-mediated cytotoxicity in the spleens of mice immunized with the transformed cells. One of the cell lines induced the generation of cell-line-specific Thy1.2-positive cytotoxic effector cells. However, most of the cell lines tested induced the generation of Thy1.2-positive effector cells, which in addition to BPV1-transformed cells were able to lyse a syngeneic cell line transformed by methylcholanthrene. The lysis of BPV1- and methylcholanthrene-transformed cell lines was mediated by recognition of the same antigenic determinants expressed on these cells, and all the BPV1-transformed cell lines were sensitive to lysis by these nonspecific effector cells of the lymphokine-activated killer (LAK) type.     

Blood pressure and five year survival in the very old

During 1977-8 we measured blood pressure in 561 old people (83% of those aged 85 or more living in Tampere) and analysed their five year survival according to their blood pressure group. The subjects were divided into six groups on the basis of their blood pressures (from <120 to >200 mm Hg systolic, from <70 to >110 diastolic). The greatest mortality was observed in those in the lowest systolic and lowest diastolic groups. Mortality was least in subjects with systolic pressures of 160 mm Hg or more and diastolic pressures of 90 mm Hg or more.The most essential finding in this series of the very old was an increased mortality in the lowest blood pressure groups.     

Monitoring white whales (Delphinapterus leucas) with echolocation loggers

Monitoring programmes for white whales (Delphinapterus leucas) have been called for repeatedly in recent years because this species is likely to be negatively impacted by climate change, but also because such a broadly dispersed, high trophic feeder can serve as an effective ecosystem sentinel. Arctic ecosystems are difficult to monitor because of the extensive winter ice coverage and extreme environmental conditions in addition to low human population densities. However, passive acoustic monitoring has proved to be a reliable method to remotely survey the presence of some marine mammals in the Arctic. In this study, we evaluate the potential use of echolocation loggers (T-POD and C-POD, Chelonia Ltd.) for remote monitoring of white whales. Captive experiments and open water surveys in three arctic/subarctic habitats (ice-noise-dominated environment, ice-free environment and low-turbidity waters) were used to document detection performance and to explore the use of logger angle and inter-click interval data to look at activity patterns and tidal influences on space use. When acoustic results were compared to concurrent visual observations, echolocation detection was only attributed to periods of white whale presence near the recorder deployment sites. Both T-PODs and C-PODs effectively detected echolocation, even under noisy ice. Diel and tidal behavioural patterns were identified. Acoustically identified movement patterns between sites were visually confirmed. This study demonstrates the feasibility of monitoring white whales using echolocation loggers and describes some important features of their behaviour as examples of the potential application of this passive acoustic monitoring method in Arctic and subarctic regions.