Intraspecific diversity in the fungal speciesChaunopycnis alba: Implications for microbial screening programs

Intraspecific variation among 84 isolates of the anamorphic fungusChaunopycnis alba from 26 different geographical locations was analyzed by investigating optimal growth temperatures, differences in the production of secondary metabolites and presence or absence of the cyclosporin synthetase gene. The genetic diversity was assessed using random amplified polymorphic DNA (RAPD). Analysis of these data showed high genetic, metabolic and physiological diversity within this species. Isolates from the Antarctic represented the most homogeneous group withinC. alba and together with isolates from the Arctic these polar strains differed from alpine, temperate and tropical strains by low optimal growth temperatures and by low production of secondary metabolites. Isolates from tropical climes were characterized by high optimal growth temperatures and by the production of comparatively diverse metabolite spectra. Most of the isolates that were similar in the combination of their physiological and metabolic characters were also genetically related. Isolates from different geographical origins did not show many similarities, with the exception of the cyclosporin A-producing isolates, and large diversity could be observed even within a single habitat. This leads us to the suggestion that for pharmaceutical screening programs samples should be collected from a diversity of different geographical and climatic locations. For the selection of strains for screening the RAPD assay seems to be the most powerful tool. It reflected the highest intraspecific diversity and the results corresponded well with the other characteristics.     

Administration of semisynthetic human insulin by a spray injector

The use of Jet injection in insulin administration pointed out the question whether this route could affect insulin absorption and plasma insulin profiles. To compare plasma insulin profiles following an administration of an identical insulin dose by jet injection or by conventional subcutaneous route (syringe with needle) 8 healthy subjects (age 24-28 yrs., non obese) were given at 09.00 h of two different days 200 mU/kg/BW of human semisynthetic regular insulin (Novo Actarapid) alternatively subcutaneously by a syringe with needle or transcutaneously by jet injection (DG 77 - Sicim - Gorizia). Before insulin administration and then 15, 30, 60, 90, 120 and 180 minutes after, blood samples were drawn for plasma insulin and C-peptide determination. Higher plasma insulin levels after administration by jet were found at 15' and 30' minutes (62,58 +/- 6,31 v.s. 36,94 +/- 3,31 microunits/ml at 15' and 76,51 +/- 9,60 v.s. 51,65 +/- 9,95 at 30', p less than 0,01 and p less than 0,005, paired Student t test). No difference could be observed for the other times. C-peptide was found to fall to undetectable values, confirming the nearly total suppression of endogenous insulin production. It is concluded that total regular insulin absorption does not differ after transcutaneous jet injection or administration by syringe with needle, but in the first case it is faster. This last finding should be considered in planning insulin treatment schedules.     

Repressor and int synthesis of bacteriophage lambda in the E. coli host mutant ER437.

Summary Analysis of phage infection of the host mutant ER437 by SDS polyacrylamide gel electrophoresis and autoradiography has revealed altered expression of repressor and integration function (Int). We show that in this host Int as well as repressor synthesis is not dependent upon the cIII gene product in the usual manner, nor is their synthesis turned off in the normal way.     

Dopamine release induced by electrical field stimulation of rat hypothalamus invitro: Inhibition by melatonin

Microdissected slices of rat hypothalamus were incubated with ³H -dopamine and then subjected to two successive sets of electrical field stimulation in a superfusion chamber. Neurotransmitter release was found to be calcium dependent and the amount of release was determined by scintillation counting of the effluent buffer. The release obtained following the first train of stimuli served as an internal reference. The samples were exposed to drugs during the interval between the two sets of stimuli. Using this technique, as well as K⁺-evoked depolarization, we were able to show that subnanomolar concentrations of melatonin, the hormone secreted from the pineal gland, inhibits dopamine release from hypothalamic slices. The possibility that melatonin modulates neurotransmission in the brain is therefore indicated.     

Lysis of autologous human melanoma cells by in vitro allosensitized peripheral blood lymphocytes

Summary Peripheral blood lymphocytes (PBL) of melanoma patients were sensitized in vitro with lymphocytes of a single donor or with a pool of lymphocytes of 5–20 different donors. After 6–7 days, the cytotoxic activity of the sensitized PBL was tested against cultured autologous tumor cells and lymphocytes in a ⁵¹Cr-release assay. Tumor lysis was observed in 13 of 16 cases in which patients' PBL (Pt-PBL) were stimulated by a pool of allogeneic lymphocytes and in five out of seven cases when single sensitization was performed. In no case was lysis of autologous normal lymphocytes or blasts seen. Cultivation of Pt-PBL with irradiated autologous tumor cells never led to the induction of lymphocytes cytotoxic to melanoma cells. Lysability by pool-activated autologous Pt-PBL of fresh cryopreserved tumor cells was compared to that of short-term cultured tumor cells, and no significant differences were observed. Cold-target inhibition experiments indicated that the cytotoxicity of Pt-PBL was tumor-restricted since only autologous melanoma cells but not lymphocytes were able to inhibit the reaction. These results indicate that activation of Pt-PBL is necessary in order to elicit or amplify their antitumor activity.     

A covalently bound photoisomerizable agonist. Comparison with reversibly bound agonists at electrophorus electroplaques

After disulphide bonds are reduced with dithiothreitol, trans-3- (α-bromomethyl)-3’-[α- (trimethylammonium)methyl]azobenzene (trans-QBr) alkylates a sulfhydryl group on receptors. The membrane conductance induced by this “tethered agonist” shares many properties with that induced by reversible agonists. Equilibrium conductance increases as the membrane potential is made more negative; the voltage sensitivity resembles that seen with 50 [mu]M carbachol. Voltage- jump relaxations follow an exponential time-course; the rate constants are about twice as large as those seen with 50 μM carbachol and have the same voltage and temperature sensitivity. With reversible agonists, the rate of channel opening increases with the frequency of agonist-receptor collisions: with tethered trans-Qbr, this rate depends only on intramolecular events. In comparison to the conductance induced by reversible agonists, the QBr-induced conductance is at least 10-fold less sensitive to competitive blockade by tubocurarine and roughly as sensitive to “open-channel blockade” bu QX-222. Light-flash experiments with tethered QBr resemble those with the reversible photoisomerizable agonist, 3,3’,bis-[α-(trimethylammonium)methyl]azobenzene (Bis-Q): the conductance is increased by cis {arrow} trans photoisomerizations and decreased by trans {arrow} cis photoisomerizations. As with Bis-Q, ligh-flash relaxations have the same rate constant as voltage-jump relaxations. Receptors with tethered trans isomer. By comparing the agonist-induced conductance with the cis/tans ratio, we conclude that each channel’s activation is determined by the configuration of a single tethered QBr molecule. The QBr-induced conductance shows slow decreases (time constant, several hundred milliseconds), which can be partially reversed by flashes. The similarities suggest that the same rate-limiting step governs the opening and closing of channels for both reversible and tethered agonists. Therefore, this step is probably not the initial encounter between agonist and receptor molecules.     

Familial true hermaphrodism in three siblings: clinical, cytogenetic, histological and hormonal studies.

Three affected siblings with the hermaphrodism are described. The propositi showed the following characteristics: male phenotype and gender role, hypospadias, bilateral scrotal ovotestes with palpable nodules, and absence of müllerian structures. The X chromatin was positive and the Y chromatin was negative in the 3 affected subjects. Their karyotype in peripheral blood lymphocytes and in gonadal fibroblasts was 46,XX and no Y chromosome fluorescence was observed. Plasma FSH was elevated in the 2 older patients and plasma LH was elevated only in the oldest. Plasma testosterone was low and plasma estradiol high in the 3 siblings; plasma progesterone was elevated in 2, but normal in 1 sibling. Since some of the clinical characteristics of these 3 affected siblings are not the most common features in the majority of sporadic cases of true hermaphrodism, it is suggested that the presence of all of them may be the first clue for the clinical suspicion of the familial type of true hermaphrodism.