The relationship between rational drug design and drug side effects

Previous analysis of systems pharmacology has revealed a tendency of rational drug design in the pharmaceutical industry. The targets of new drugs tend to be close with the corresponding disease genes in the biological networks. However, it remains unclear whether the rational drug design introduces disadvantages, i.e. side effects. Therefore, it is important to dissect the relationship between rational drug design and drug side effects. Based on a recently released drug side effect database, SIDER, here we analyzed the relationship between drug side effects and the rational drug design. We revealed that the incidence drug side effect is significantly associated with the network distance of drug targets and diseases genes. Drugs with the distances of three or four have the smallest incidence of side effects, whereas drugs with the distances of more than four or smaller than three show significantly greater incidence of side effects. Furthermore, protein drugs and small molecule drugs show significant differences. Drugs hitting membrane targets and drugs hitting cytoplasm targets also show differences. Failure drugs because of severe side effects show smaller network distances than approved drugs. These results suggest that researchers should be prudent on rationalizing the drug design. Too small distances between drug targets and diseases genes may not always be advantageous for rational design for drug discovery.     

Cryopreservation produces limited long-term effects on the nematode Caenorhabditis elegans

Cryopreservation, the freezing and later warming of biological samples with minimal loss of viability, is important in many scientific disciplines. For some applications, particularly those where there is limited available material, it is critical to ensure the maximal survival rates of cryopreserved materials. Most of the challenges encountered with such techniques take place after the warming process where cryodamage affects cell viability and future development. Here we have used the nematode Caenorhabditis elegans to investigate the effects of cryodamage caused by slow-freezing. We find that freezing results in the death of some worms, with an approximately 40% reduction in the number of worms that develop in the frozen populations, but that the effects on worms that survive are limited. For example, there are no differences in the lifetime fecundity or in lifespan between frozen and control worms, although early fecundity and body size was reduced in frozen worms. Similarly, analyses of body wall muscle structure and of pharyngeal function indicates that muscle development and function are not significantly affected by freezing. We do however determine that freezing increases the rates of matricidal hatching, where progeny hatch within the mother. Overall, these results indicate that, for worms that survive, cryopreservation produces limited long-term effects, but do indicate that some phenotypes could be used in further analyses of the cellular damage induced by cryopreservation.     

Feedback and incentive effects on the decrease of interbeat interval

Johnston and Lethem (1981) have hypothesized that when subjects attempt to decrease their interbeat interval (i.e., increase their heart rate) maximally, then interbeat interval feedback has a purely motivational role, but when they attempt to decrease their interbeat interval by a precise amount, such feedback has a primarily informational role. This was tested by comparing the performance of 16 subjects on both types of task. It was predicted that additional monetary incentives would reduce the difference between feedback and no-feedback conditions when subjects were attempting to reduce interbeat interval maximally but not when attempting to reduce it by a specific amount. This prediction was not supported. Incentive was found to aid performance on the maximal interbeat interval decrease task, but this was independent of the effects of feedback. Only feedback effects were detected on the specific interbeat interval decrease task.     

Active immunoneutralization of somatostatin in the sheep: effects on gastrointestinal somatostatin expression, storage and secretion.

In the absence of somatostatin antagonists, somatostatin antisera administered acutely or animals chronically immunized against somatostatin have been used to define the functions of somatostatin. However, the circulating immunoglobulins from immunized animals may contain substantial quantities of endogenous hormones. This has not been examined for somatostatin. We have measured the amount of free somatostatin bound to circulating immunoglobulins in somatostatin-immunized animals and the effect of this sequestering of the free peptide on somatostatin secretion and gastric somatostatin synthesis and storage. The average concentration of somatostatin bound to the antisera was 6.9 nmol/l, about 1000-fold higher than normal circulating levels. Compared to control animals, there was a doubling of somatostatin mRNA in the fundus and a 4-fold increase in fundic somatostatin peptide. Similar increases were seen in pancreas, but the antrum was not significantly affected providing further evidence of distinct regulatory mechanisms between the antrum and fundus. We suggest that withdrawal of active somatostatin activates a regulatory loop to increase fundic somatostatin biosynthesis and storage. The data support the concept that somatostatin autoregulates its own expression at both the RNA and peptide level.     

Learned helplessness: effects of response requirement and interval between treatment and testing

Three experiments investigated learned helplessness in rats manipulating response requirements, shock duration, and intervals between treatment and testing. In Experiment 1, rats previously exposed to uncontrollable or no shocks were tested under one of four different contingencies of negative reinforcement: FR 1 or FR 2 escape contingency for running, and FR1 escape contingency for jumping (differing for the maximum shock duration of 10s or 30s). The results showed that the uncontrollable shocks produced a clear operant learning deficit (learned helplessness effect) only when the animals were tested under the jumping FR 1 escape contingency with 10-s max shock duration. Experiment 2 isolated of the effects of uncontrollability from shock exposure per se and showed that the escape deficit observed using the FR 1 escape jumping response (10-s shock duration) was produced by the uncontrollability of shock. Experiment 3 showed that using the FR 1 jumping escape contingency in the test, the learned helplessness effect was observed one, 14 or 28 days after treatment. These results suggest that running may not be an appropriate test for learned helplessness, and that many diverging results found in the literature might be accounted for by the confounding effects of respondent and operant contingencies present when running is required of rats.     

The effects of somatostatin on the arachidonate cascade of platelets

Somatostatin (10(-9) M) significantly elevated the synthesis of thromboxane B2 in rat platelets. The transformation of arachidonic acid to active lipoxygenase metabolites was suppressed by somatostatin (10(-9) and 10(-8) M). The ratio of the lipoxygenase/cyclooxygenase products was significantly reduced by the polypeptide (10(-9) and 10(-8) M) in rat platelets. Higher concentrations (10(-7), 10(-6) and 10(-5) M) of somatostatin did not modify the lipoxygenase pathway of the platelets. The synthesis of the vasoconstrictor - proaggregatory cyclooxygenase products was stimulated by the polypeptide (10(-9) and 10(-8) M), while the formation of vasodilatator - antiaggregatory cyclooxygenase metabolites was induced by higher concentrations of somatostatin (10(-7) and 10(-6) M). Somatostatin might act on the deacylation process of phospholipids, reducing the free arachidonic acid substrate level, resulting in a lower lipoxygenation rate in the platelets, which could be responsible for the increased formation of thromboxane. The contradictory results reported by others concerning the action of somatostatin on the platelet function might be explained by our results that the effect of somatostatin depends on the applied dose.     

The effects of somatostatin on the arachidonate cascade of platelets

Somatostatin (10⁻⁹ M) significantly elevated the synthesis of thromboxane B₂ in rat platelets. The transformation of arachidonic acid to active lipoxygenase metabolites was suppressed by somatostatin (10⁻⁹ and 10⁻⁸ M). The ratio of the lipoxygenase/cyclooxygenase products was significantly reduced by the polypeptide (10⁻⁹ and 10⁻⁸ M) in rat platelets. Higher concentrations (10⁻⁷, 10⁻⁶ and 10⁻⁵ M) of somatostatin did not modify the lipoxygenase pathway of the platelets. The synthesis of the vasoconstrictor — proaggregatory cyclooxygenase products was stimulated by the polypeptide (10⁻⁹ and 10⁻⁸ M), while the formation of vasodilatator - antiaggregatory cyclooxygenase metabolites was induced by higher concentrations of somatostatin (10⁻⁷ and 10⁻⁶ M). Somatostatin might act on the deacylation process of phospholipids, reducing the free arachidonic acid substrate level, resulting in a lower lipoxygenation rate in the platelets, which could be responsible for the increased formation of thromboxane. The contradictory results reported by others concerning the action of somatostatin on the platelet function might be explained by our results that the effect of somatostatin depends on the applied dose.     

Comparative biochemical effects of the injection of cyclic and linear forms of vertebrate somatostatin on the honeybee in vivo. II. Blood lipids

The linear and cyclic forms of vertebrate somatostatin were injected to worker honeybees at the rate of 50 ng per individual, and their effects on the lipemia were compared between themselves and with those of saline injection over a 3 hrs period. Both hormonal forms elicit a global decrease of the levels of phospholipids, steroids, fatty acids, diacyl and triacyl glycerol, by contrast with hyperlipemic effects induced by the injection of saline alone. The kinetics of variations show a remarkable phase concordance between the respective effects of both hormonal forms, with strong positive correlations in the case of phospholipids, fatty acids and glycerides. The linear and cyclic forms of somatostatin thus show similar effects counteracting the results of the release of endogenous hormones following the stress associated to the microsyringe stinging.     

Dynamics of the gamma-responses in an 8-second interval between facial and trigger stimuli as dependent the success of task performance

A cognitive set to facial expression was used as a model with the loading on working memory being increased by increasing the interval between the facial and triggering stimuli to 8 seconds. The aim was to determine whether the intensity of brain potentials evoked in a range of 41–60 Hz (the range 15–60 Hz was used) by facial stimuli is associated with the “success” of task performance (mistake rate). An index of average amplitudes of EEG oscillations was used to measure the response to facial stimuli, and γ responses proved to be associated with the number of mistakes in performing the task. The results make it possible to consider the γ responses to facial stimuli as an EEG correlate of the internal states that correspond to adequate actions of the subject in the test with a 8-s interval between the facial and trigger stimuli.     

Magnetic fields and time dependent effects on development

Pulsed, extremely-low-frequency electromagnetic fields caused a significant increase in abnormalities in the developing chick embryo. The effect was observed when the field was presented during the first 24 h of incubation; no significant effect was observed with exposure from 24 to 48 h of incubation.     

Effects of injection of hcg during the estrous cycle on follicle development and the inter-estrous interval

Pseudopregnancy in pigs can be induced by the administration of a single dose of hCG at Day 12 of the estrous cycle. However, the resulting length of pseudopregnancy can be extremely variable. In this study, it was investigated whether time of hCG administration (day of the cycle) and degree of follicle growth after hCG administration were related to the length of inter-estrous interval (pseudopregnancy). In the first experiment, groups of cyclic gilts were given 1500 IU hCG at either Day 11 (D 11; n=14) or Day 12 (D12; n=14) after onset of estrus, or not treated (Control; n=13). Follicle development was assessed daily using transcutaneous ultrasonography. Follicle size in the Control gilts remained relatively constant between Days 11 and 17, whereas in the treated gilts, follicle size increased (P < 0.001) within 4 days (D11) and 2 days (D12) after treatment. The inter-estrous interval was increased (P < 0.01) in the hCG-treated gilts (34.7+/-6.3 and 37.6+/-11.1 days in the D11 and D12 gilts, respectively), compared to Controls (22.3+/-5.2 d). About two-thirds of the treated gilts returned to estrus between Days 32 and 39 after onset of first estrus. No relationships were found between follicle development after treatment and length of the inter-estrous interval. In a second experiment, 16 cyclic gilts were treated with 1500 IU hCG at Day 12 and Day 15 of the estrous cycle. Follicle development was assessed at Days 12, 15 and 18. At Day 18, average follicle size was 8.4+/-2.0 mm. The inter-estrous interval was 39.7+/-5.4 days and 14 of 16 gilts returned to estrus between Days 34 and 44 after onset of first estrus. Again, no relationships were found between follicle development after treatment and the duration of the inter-estrous interval. We conclude that, based on the duration of the inter-estrous interval, administration of hCG during the luteal phase induced a short pseudopregnancy. However, the induction of accessory corpora lutea or follicular luteinization cannot be discounted.     

Combined effects of cold and somatostatin on glucose kinetics in dogs

The role of the endocrine pancreas in glucose production (Ra), utilization (Rd), and metabolic clearance (R'd) was investigated during acute exposure to cold in normal normothermic dogs. Two ambient temperatures (TaN = +25 degrees C and TaC = -21 degrees C) were selected. At TaC, metabolic rate and glucose turnover of the shivering dogs were 4.3 and 2.4 times, respectively, higher than in dogs resting at TaN. As compared with the pre-experimental period, somatostatin infusion at TaN induced a 25% (arterial) and 34% (portal) glucagon deficiency, while insulin concentration dropped by 59% (arterial) and 74% (portal). Similar values were obtained at TaC for glucagon (39% arterial and 47% portal) and for insulin (52% arterial and 56% portal). At TaN, these simultaneous hormonal alterations provoked a slight reduction in plasma glucose concentration which levelled down to 4.4 mM. This reduction was due to a decrease in Ra, followed by a parallel decrease in Rd whereas R'd remained unchanged. At TaC, plasma glucose concentration dropped to the same level but quickly rose again during somatostatin infusion. This rise was due to a larger reduction in Rd than in Ra, accompanied by an abrupt fall in R'd. This reduction in R'd appears to be an important mechanism able to restore euglycemia during global pancreatic hormone deficiency in cold exposed dogs.     

Palbociclib can overcome mutations in cyclin dependent kinase 6 that break hydrogen bonds between the drug and the protein

Inhibition of cyclin dependent kinases (CDKs) 4 and 6 prevent cells from entering the synthesis phase of the cell cycle. CDK4 and 6 are therefore important drug targets in various cancers. The selective CDK4/6 inhibitor palbociclib is approved for the treatment of breast cancer and has shown activity in a cellular model of mixed lineage leukaemia (MLL)‐rearranged acute myeloid leukaemia (AML). We studied the interactions of palbociclib and CDK6 using molecular dynamics simulations. Analysis of the simulations suggested several interactions that stabilized the drug in its binding site and that were not observed in the crystal structure of the protein‐drug complex. These included a hydrogen bond to His 100 that was hitherto not reported and several hydrophobic contacts. Evolutionary‐based bioinformatic analysis was used to suggest two mutants, D163G and H100L that would potentially yield drug resistance, as they lead to loss of important protein–drug interactions without hindering the viability of the protein. One of the mutants involved a change in the glycine of the well‐conserved DFG motif of the kinase. Interestingly, CDK6‐dependent human AML cells stably expressing either mutant retained sensitivity to palbociclib, indicating that the protein‐drug interactions are not affected by these. Furthermore, the cells were proliferative in the absence of palbociclib, indicating that the Asp to Gly mutation in the DFG motif did not interfere with the catalytic activity of the protein.     

Comparative effects of somatostatin and enkephalins on the guinea pig ileum and the rat vas deferens

The action of somatostatin (SRIF (somatotrophin release inhibiting factor)) was compared with that of Met-enkephalin (Tyr-Gly-Gly-Phe-Met) in the electrically stimulated guinea pig ileum myenteric plexus longitudinal muscle and with that of an enkephalin analogue (FK 33-824 (Tyr-D-Ala-Gly-MePhe-Met-(O)-ol)) in the rat vas deferens. In both tissues SRIF produced a twitch inhibition which was not antagonized by naloxone and which showed a long-lasting tachyphylaxis. The enkephalins tested produced a naloxone-antagonizable inhibition of twitch in both tissues but no tachyphylaxis. Therefore we conclude that SRIF is not acting at opiate receptors in these tissues.     

Pain relieve after impacted wisdom teeth extraction dependent on the drug therapy

Purpose of this study was to compare the effects of combined therapy using nonsteroid anti-inflammatory analgetics and corticosteroids, and the effects of the mono-therapy with same drugs for post-operative pain after surgical removal of the impacted mandibular third molar. The study was completed at the Department of Oral Surgery and at the Department of Dental Medicine of the Public Institute Health Center Zenica in Zenica. The research included 60 patients divided into 3 groups using random selection, including both sexes. Age range was between 18 and 45 years. All participants came without any pain or other inflammatory symptoms at the time of oral surgical intervention. Two medicaments were prescribed after the impacted tooth removal: 15 mg of nonsteroid anti-inflammatory analgesic drug (Meloxicam, Bosnalijek, BiH) and 32 mg Methylprednisolone (corticosteroid, Bosnalijek, BiH). Both medicaments were applied per os, according to schedule determined by the research protocol. The level of post-surgical pain was evaluated by the 1-10 visual analog scale (VAS). One way ANOVA was made with Tuckey post-hoc tests. Statistically significant difference (p < 0.05) was found between the group treated with mono therapy and the group treated with combined therapy. Application of monotherapy using only corticosteroids or only nonsteroid anti-inflammatory pain-killers was less effective compared to the combined therapy with both medicaments after surgical removal of the impacted mandibular third molar.