Trypsin-mediated semisynthesis of salmon calcitonin

Salmon calcitonin, CT(1-32)·NH₂, was synthesised by the trypsin-mediated coupling of the peptide fragments CT(1-24) and CT(25-32)·NH₂, prepared by conventional Fmoc solid-phase chemistry. Optimal conditions regarding reaction time course, pH, proportion of catalyst, substrate concentration and composition of the reaction medium were determined from initial studies on the coupling of CT(1-11) to CT(12-24) and of CT(12-24) to CT(25-32)·NH₂. For the final successful semisynthesis, we found that it was unnecessary to protect lysine residues not involved in the coupling, and that secondary hydrolysis at these sites could be prevented by increasing the pH of the reaction medium. The reaction achieved equilibrium after 30-45 min, with overall conversion of around 30% of the initial amount of CT(1-24) substrate into product. Yields were depressed due to cyclisation of the CT(1-24) substrate via air-oxidation of the Cys¹ and Cys⁷ residues.     

Screening for alcoholism

Alcoholism is one of the largest public health problems of the nation and is a significant cofactor in such ubiquitous diseases as hypertension, developmental abnormalities, heart failure, liver failure, and many other conditions. The cost to the nation's health is immense. One strategy for reducing morbidity and cost has been to establish methods for screening in order to increase recognition rates leading to increased rates of therapeutic intervention. In this article, the rationale for two methods of alcohol screening, brief interviews and biological markers of excessive drinking, the relevant statistical issues bearing on this problem, and the current research on screening exams are reviewed and summarized. Finally, some of the newer approaches toward alcoholism screening as well as the consequences to the medical care system should alcohol screening eventuate on a large scale are briefly described.     

Effect of oral and inhaled cetirizine in allergen induced bronchoconstriction

Cetirizine is a potent, selective H₁ histamine receptor antagonist. The effect of oral and inhaled eetirizine was assessed on the early bronchoconstrictor response to inhaled allergen in 10 mild atopie asthmatic patients in a double-blind, randomized, plaeebo controlled trial. All were sensitive to Dermatophagoides pleronyssinus and this was used as the provoking allergen. The geometric mean PD20 FEV] values obtained at allergen challenge were measured as cumulative breath units (c.b.u.) and following oral cetirizine, inhaled cetirizine and placebo were 124–5, 75–7 and 76–7 c.b.u. respectively. These did not differ significantly. We conclude that neither oral nor inhaled cetirizine significantly attenuates the early response to inhaled allergen in atopie asthmatic subjects. However, the method of repeated allergen challenge is likely to be relatively insensitive. Clinical and Experimental Allergy, [o]. 23, pp. 528–531.     

INAUGURAL ARTICLE by a Recently Elected Academy Member:From oligonucleotide shapes to genomic SELEX: Novel biological regulatory loops

The SELEX method and oligonucleotide combinatorial chemistry discovery process yields high-affinity/high-specificity ligands for virtually any molecular target. Typically, the enormous starting libraries used in the SELEX process contain 10¹⁴–10¹⁵ sequences. We now ask if the smaller sequences, complexity of extant organisms, and evolutionary history provide useful interactions between oligonucleotides and at least some unexpected targets. That is, do organisms contain a robust “linkage map” between their oligonucleotides and proteins and/or small molecules that enriches life?     

The influence of anaesthetic techniques and type of delivery on peripartum serum interleukin-6 concentrations

Background: Interleukin-6 is a pleiotropic cytokine with a wide range of physiological activities. It plays an important role in the immuno-neuro-humoral axis during stress and surgery.
Methods: Serum interleukin-6 in parturients was measured on hospital admission, immediately after birth and 12 and 24 hours later. All parturients had uncomplicated pregnancies, and delivered vaginally without (n=31) or with (n=20) epidural analgesia, or underwent Caesarean section under epidural (n=20) or general (n=10) anaesthesia.
Results: Serum interleukin-6 assayed immediately following Caesarean section was low, but peaked 12 hours later, irrespective of the anaesthetic technique or other foetomaternal characteristics. Patients who delivered vaginally showed the highest interleukin-6 levels immediately after delivery. These were positively correlated with serum interleukin-6 on admission and duration of labour. Serum interleukin-6 was significantly higher in parturients who had epidural analgesia, and was significantly lower in those receiving intravaginal prostaglandins compared to those without prostaglandins.
Conclusion: The interleukin-6 response after Caesarean section can be explained by a generalized acute phase response to surgery, with no anaesthetic, maternal or neonatal interference. The rapid increase in peripartum serum interleukin-6 levels after vaginal delivery reflects, in part, cervical ripening or labour, their physiological triggers and psychological or physical stress. Regional anaesthesia, duration of labour and exogenous prostaglandin administration can modulate the peripartum interleukin-6 response and subsequently the physiological effects of this cytokine.     

Ventilatory effects of dexmedetomidine, atipamezole, and isoflurane in dogs.

Dexmedetomidine (DMED) is a novel alpha 2 adrenergic agonist that has been shown to have potent analgesic and anesthetic sparing effects. This study was designed to investigate the effects of DMED, both alone and combined with isoflurane, on resting ventilation, the hypercapnic response, and the hypoxic response in dogs. When given alone, 1 microgram/kg decreased resting ventilation by 22% but at larger doses (10, 20, and 100 micrograms/kg) resting ventilation increased, doubling at 100 micrograms/kg. Doses of 10 micrograms/kg and greater caused a maximum depression of 60% in the slope of the hypercapnic response, but no dose had a significant effect on the hypoxic ventilatory response. A dose of 3 micrograms/kg of DMED reduced isoflurane MAC from 1.3% to 0.37%, and the ventilatory effects of this 1 MAC combination were intermediate between the awake values and those of isoflurane-anesthetized (1.3%) dogs. Atipamezole is a specific centrally acting alpha 2 receptor antagonist and when given with DMED in isoflurane-anesthetized dogs prevented the ventilatory depression. However, atipamezole alone also ventilatory stimulating effects, which may indicate tonic alpha 2 adrenergic activity. The ventilatory depression caused by DMED, either alone or combined with isoflurane, at doses that significantly reduce anesthetic requirements are relatively mild.     

Action of beer and its ingredients on gastric acid secretion and release of gastrin in humans

The intragastric action of beer and its known ingredients before and after fermentation on gastric acid secretion and release of gastrin was studied in healthy humans. None of 11 tested ingredients of fermented beer (2 x 500 mL, pH 5.5, given either alone or in combination) or hop extract had any significant effect. Finished beer (6 weeks old) and new beer were potent stimuli of acid output, causing 93% and 76% of the incremental maximal acid output in response to pentagastrin (6 micrograms/kg SC), respectively. Before the addition of yeast, preproducts of beer were considerably less potent. Thus, first and finished wort caused only a minor acid response which was 48% and 46% of maximal acid output. Foreign fermentation in first and finished wort is presumably the reason for the stimulatory action because glucose solutions in concentrations (11.5% wt/vol) seen in wort did not stimulate acid secretion. However, glucose solutions to which yeast was added, resulting in fermentation, were as potent stimuli of acid secretion as beer. Lyophilization of beer at pH 11.0 and dialysis (cutoff mol wt, 1000) removed the stimulatory substances. The plasma gastrin responses paralleled the gastric acid response to the different stimulants. It was concluded that (a) the addition of yeast to finished wort and the following alcoholic fermentation are the essential steps for the stimulatory action of beer on gastric acid secretion and release of gastrin; (b) carbohydrate metabolites with a molecular weight of less than 1000 are the acid-stimulatory agents in fermented beer; and (c) gastrin is the mediator of the stimulation of acid secretion because all substances that had a potent acid-stimulatory action also were potent stimuli of gastrin release.     

Developmental changes in the susceptibility to long-term potentiation of neurones in rat visual cortex slices.

We investigated with intracellular recordings from rat visual cortex slices whether the susceptibility to undergo long-term potentiation (LTP) is age-dependent and whether it is correlated with the expression of synaptic responses mediated by N-methyl-D-aspartate (NMDA) receptors. Test and tetanic stimuli were applied to the white matter and post-tetanic modifications of the amplitude of postsynaptic potentials (PSPs) were assessed in regular spiking cells of supragranular layers. At 2 weeks of age, the amplitudes of early (8-10 ms post-stimulus) and late (20 ms post-stimulus) PSP-components increased after tetanic stimulation to 137.1 +/- 13.4% and 141.3 +/- 12.1% of the pretetanic controls, respectively. At 3 weeks, potentiation of both PSP-components was less pronounced but still significant, the late component being on average more potentiated than the early one. At 4 weeks, PSPs were no longer potentiated. Bath application of 25 microM DL-2-amino-5-phosphonovalerate (APV), an NMDA receptor antagonist, blocked LTP induction both at 2 and at 3 weeks. We also studied developmental changes of two synaptic responses known to influence the susceptibility of cortical neurones to LTP, the NMDA receptor-mediated excitatory PSP (EPSP) and the initial inhibitory PSP (iIPSP). The amplitude of the APV-sensitive EPSP decreased with age and reached adult values in 4-week-old animals. The iIPSPs were pronounced already at 2 weeks and showed no marked change during further development. The results suggest a close correlation between the susceptibility to undergo LTP and the extent to which NMDA receptor-gated conductances contribute to the synaptic response.(ABSTRACT TRUNCATED AT 250 WORDS)