The characteristics of the analgesic action of nitrosorbide and no-shpa]

The dehydrogenase (DHG) or oxidation-reduction test is proposed for use together with the determination of such enzymes as hydrolases, cytochrome oxidase, dehydrocarboxylase, urease, etc. 200 Citrobacter freundii cultures and 76 strains of enteropathogenic Escherichia (EPE) were studied with the determination of their DHG activity in semiliquid mannitol and in Kligler's medium. The study revealed that this test, characterized by the reduction of the indicator, similarly to that in salmonellae and shigellae, was constantly negative in semiliquid mannitol in C. freundii and in 97.3% of cases in EPE. In 17.5% of C. freundii lactose-positive cultures the DHG test in Kligler's medium was positive, which made it possible to regard them as a separate biovar. Taking into account the results of this investigation, the subdivision of C. freundii into 3 biovars is proposed.     

Nucleic acid concentration in the brains of inbred rats of different strains

The changes of nucleic acids content in the formation of conditioned skin-defence reflex was studied on inbred rats of various strains. In WGA rats the reflex was formed on the average aight stimulations. An increased RNA content was discovered by cytophotometric determination of the nucleic acids content in the neurons and perineural glia of the cerebral cortex in August rats only. It is assumed that an increased RNA synthesis in the animals of this strain can serve as the basis for their better training.     

Central modulation of Brewer''s yeast-induced peripheral inflammation by neuropeptides bradykinin and substance P

This study reports the results of some voluntary Italian radiologists performing 103 proficiency tests in clinical (100 patients, 32 cancers) and screening mammography (150 patients, 17 cancers). Relative to the average accuracy of a panel of expert radiologists, 12 of 49 readers (27%) and 32 of 54 readers (56%) passed the clinical and screening mammography test, respectively. The results were significantly correlated with the readers' previous experience (years of mammographic practice [< 2, 2-4, > 4] and number of mammograms read [< 5,000, 5-10,000, > 10,000]). The rate of passed test was: < 2 years = 0%, 2-4 years = 40%, > 4 years = 66.6% (P = 0.002); < 5,000 mammograms read = 15.3%, 5-10,000 = 28.5%, > 10,000 = 69.2% (P = 0.02). The best results were achieved by the readers with a previous reading experience of at least 10,000 mammograms, a figure which might be used as the reference for a future criterion of accreditation on a national basis. Proper training before reporting mammography is fundamental to ensure a good diagnostic performance. The low number of tests performed in most Italian mammographic practice facilities makes local training highly questionable and requires quite a long time. Reference centers, adequately equipped for training, should be identified for this purpose. Proficiency tests such as those described in the present study are useful to assess individual performance and should be a part of a training program.     

Differential effects of prenatal stress in two inbred strains of rats

Glucagon-like peptide-1 (GLP-1) may be one of the enterogastrone hormones of the ileal brake mechanism. We therefore studied its effects on gastric lipase secretion in healthy volunteers and vagotomized patients during infusion of pentagastrin. The intestinal incretin hormone GLP-1 (glucagon-like peptide-1, 7-36 amide) was investigated because of its inhibitory effects on gastric acid secretion and motility. GLP-1 infused intravenously in amounts corresponding to the postprandial release significantly inhibited pentagastrin-stimulated gastric lipase secretion and lipolytic activity. The inhibitory effect of GLP-1 persisted in vagotomized patients, suggesting that fundic chief cells, from which gastric lipase is released, or neighboring inhibitory cells could be equipped with GLP-1 receptors. Vagotomized patients had significantly higher plasma concentrations of gastrin and secretin. No significant changes of gastrin, secretin, and CCK secretion were seen during GLP-1 infusion in the vagotomized patients, whereas secretin decreased significantly in the healthy volunteers. GLP-1 seems to be a naturally occurring inhibitor of gastric lipase secretion acting via a nonvagal mechanism. Our results indicate that gastric lipase secretion is subject to hormonal stimulatory as well as inhibitory mechanisms.     

Spectrum of aerobic endurance running performance in eleven inbred strains of rats

Mice homozygous for a disruption in the Mdr2 gene (Mdr2 (-/-) mice) lack the Mdr2 P-glycoprotein (P-gp) in the canalicular membrane of the hepatocyte and are unable to excrete phosphatidylcholine into the bile. These mice develop a nonsuppurative cholestatic liver disease, presumably caused by the high concentrations of free cytotoxic bile acids in bile. We generated transgenic mice that express the human homolog of Mdr2, MDR3, specifically in the liver by the use of an albumin promoter. In these mice the MDR3 P-gp is exclusively located in the canalicular membrane of hepatocytes and phospholipid excretion into bile is restored. Mice that contain the same amount of MDR3 P-gp as that of Mdr2 P-gp in wild-type mice, also excrete the same amount of phospholipids. No histopathological abnormalities were observed in the livers of these mice. In mice that express MDR3 at a higher or lower level, the phospholipid excretion correlated with the amount of MDR3 P-gp. We conclude that the human MDR3 P-gp is functionally homologous to the murine Mdr2 P-gp and that it can fully replace this P-gp in Mdr2 (-/-) mice, restoring the excretion of phospholipids into the bile. The phospholipid excretion is limited by the amount of MDR3 or Mdr2 P-gp. The excretion of cholesterol is not tightly coupled to the excretion of phospholipids in these mice, because a very low phospholipid excretion level is sufficient to give almost wild-type cholesterol excretion into the bile.     

Vasorelaxation in isolated bone arteries. Vasoactive intestinal peptide, substance P, calcitonin gene-related peptide, and bradykinin studied in pigs

We assessed the effects of vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), substance P (SP), and bradykinin in arteries (diameter approximately 230 microns) isolated from cancellous bone from pigs. Arterial segments (2 mm long) were mounted on a myograph for measurement of isometric force development. After submaximal precontraction with norepinephrine, VIP (10(-10)-10(-7) M), CGRP (10(-11)-10(-7) M), SP (10(-6) M), and bradykinin (10(-11)-10(-6) M) were added. 44 arterial segments (23 pigs) were investigated. VIP-, CGRP-, and bradykinin induced a concentration-dependent vasorelaxation, while SP mediated a transient relaxation. After mechanical removal of the endothelium, the effects of SP and bradykinin were completely abolished, while the relaxation to CGRP was still pronounced. This indicates that the effects of SP and bradykinin are mediated by the endothelium, while CGRP mainly mediates relaxation by a direct effect on vascular smooth muscle cells. The relaxations to CGRP and bradykinin were still significant after inhibition of nitric oxide synthase with 10(-4) M N omega-nitro-L-arginine (L-NNA) and inhibition of prostaglandin synthesis with 10(-5) M indomethacin, indicating the existence of an alternative vasorelaxing pathway. Our findings support the theory of a vasoregulatory role of neuropeptides in bone.     

DNA fingerprinting for genetic monitoring of inbred laboratory rats and mice

DNA fingerprinting using a nonisotopically labeled minisatellite probe provided a valuable technique for genetic monitoring/quality control of laboratory rodents. Each of 12 inbred rat strains had a unique fingerprint pattern, and colonies separated for over 20 years had identical or nearly identical patterns. Strain LOU/Iap, which is known to have been genetically contaminated in the past, was clearly different from strain LOU/CN, supporting previous findings of studies using biochemical markers. Inbred strains of mice were also found to differ from each other. The F1 hybrid between C57BL/6 and CBA/Ca could not be distinguished from C57BL/6 by using DNA fingerprints, although they could be distinguished by using biochemical markers. Some congenic strains differed from their inbred partner. A suspected genetic contamination of MRL/Mp-lpr mice could not be detected in a sample of the breeding colony by using biochemical markers; however, DNA fingerprints from the suspect animals clearly demonstrated genetic segregation. DNA fingerprinting will be of particular value in investigating suspected problems as only a small sample of fresh, frozen, or ethanol-preserved tissue is needed. Thus, the actual suspect animals can be studied, rather than samples from a breeding colony from which contaminated animals may already have been eliminated.     

Changes in substance P in the jejuna of rats after burns

Ecgonine is formed by the hydrolysis of both ester linkages in cocaine and is of interest as both a potential metabolite and a postmortem and postcollection artifact in biological specimens. Its extreme polarity and water solubility make its isolation very difficult, particularly from complex matrices such as postmortem whole blood. This procedure describes an initial protein precipitation followed by two derivatization steps, the first of which is to propylate organic acids and primary and secondary amines and the second of which is to form the p-nitrobenzoyl ester of organic alcohols. The resultant derivatized products are then subjected to cleanup using a standard extraction with n-butyl chloride as the solvent. Analysis of the extracts is performed by gas chromatography-mass spectrometry using deuterated internal standards, although the adducts would also be suitable for analysis by high-performance liquid chromatography. Significant quantities of ecgonine have been identified in postmortem whole blood samples using this method.     

The analgesic and antidepressant action of adrenaline-induced stress in the endogenous activation of the gastric afferent systems in rats

Adrenaline-induced stress as well as exogenous cholecystokinin exerted analgetic, antidepressant, and antistress effect upon depressive rats with high nociceptive sensitivity. The effect seems to be due to stimulation of chemoreceptors of the stomach vagal afferents by means of cholecystokinin secretion into the gastric lumen.     

Self-administration of neurokinin substance P into the ventromedial caudate-putamen in rats

There is evidence that the neurokinin substance P plays a role in learning and reinforcement processes. Reinforcing effects of substance P were found upon injection into several parts of the brain. The aim of the present study was to gauge possible reinforcing effects of microinjections of substance P into the ventromedial caudate-putamen in rats. Two different behavioral paradigms were employed. In the first experiment a two-compartment choice procedure was used and the rats could trigger substance P injections (500 pg per 5 nl injection volume) into the ventromedial caudate-putamen by entering one distinctive compartment. During the injection period, substance P-injected animals spent significantly more time in the drug-paired compartment than vehicle-injected controls. In the second experiment, nose-poking through a hole in one wall of the cage was used as the operant. Rats that could self-administer substance P (100 pg per 5 nl injection volume) into the ventromedial caudate-putamen emitted a significantly higher rate of operant responding on the first day of testing and a significantly lower rate on the third day compared to vehicle-injected animals. The experiments provide evidence that the administration of substance P into the ventromedial part of the caudate-putamen can have positive reinforcing effects, but that repeated injections can have aversive properties. These effects are discussed, firstly, with regard to the possible mechanisms of intrastriatal substance P on striatonigral and striatopallidal output systems and, secondly, with respect to their possible relevance in the study of the basal forebrain reinforcement system.     

Nitric oxide in the contractile action of bradykinin, oxytocin, and prostaglandin F2 alpha in the estrogenized rat uterus

Experiments were performed on uteri from estrogen-primed female rats. Bradykinin (BK) (10(-8) M) significantly augmented biosynthesis of prostaglandin F2 alpha (PGF2alpha) and prostaglandin E2 (PGE2), and this synthesis was completely blocked by NG-monomethyl L-arginine (NMMA) (300 microM), a competitive inhibitor of nitric oxide synthase (NOS). Blockade of prostaglandin synthesis by indomethacin caused rapid dissipation of isometric developed tension (IDT) induced by BK. Blockade of NOS with NMMA had similar but less marked effects. Combining the two inhibitors produced an even more rapid decay in IDT, suggesting that BK-induced NO release maintains IDT by release of prostanoids. The decline of frequency of contraction (FC) was not significantly altered by either indomethacin or NMMA but was markedly accelerated by combination of the inhibitors, which suggests that PGs maintain FC and therefore FC decline is accelerated only when PG production is blocked completely by combination of the two inhibitors of PG synthesis. The increase in IDT induced by oxytocin was unaltered by indomethacin, NMMA or their combination indicating that neither NO nor PGs are involved in the contractions induced by oxytocin. However, the decline in FC with time was significantly reduced by the inhibitor of NOS, NMMA, suggesting that FC decay following oxytocin is caused by NO released by the contractile process. In the case of PGF2alpha, NMMA resulted in increased initial IDT and FC. The decline in FC was rapid and dramatically inhibited by NMMA. Receptor-mediated contraction by BK, oxytocin, and PGF2alpha is modulated by NO that maintains IDT by releasing PGs but reduces IDT and FC via cyclic GMP.     

The effect of substance P upon middle ear effusion of secretory otitis media and the mode of action

BACKGROUND: The lumbosacral lucent cleft was first described in association with traumatic injuries to the neck. However, we have observed this sign to be present in patients with no precursor of trauma, and we reviewed the incidence of lucent cleft sign in our local population and any characteristic features of the lucent cleft. METHODS: Four-hundred and thirty lumbosacral spine radiographs were examined prospectively over an 8-month period, with correlation with clinical findings. Follow-up radiographs were obtained at 1, 3 and 6 months for patients with the lucent cleft sign. FINDINGS: Nineteen patients (4.4%) were found to have lucent clefts in their lumbosacral spine X-rays. No significant change in the number and features to the lucent clefts was noted even when the symptoms had resolved after 6 months. All the lucent clefts were linear, horizontally oriented and located at the anterior edge of the adjacent vertebral body. CONCLUSION: The lucent cleft sign in the spine, which has so far been described in association with has spinal trauma may be completely innocuous in patients with little or no symptoms.     

The enkephalinase mechanisms of the resistance and tolerance to the analgesic effect of morphine in rats. Differences in the effects of the action of D-phenylalanine in morphine-sensitive, morphine-tolerant and morphine-resistant rats

In morphine-sensitive (s.c. 1.5 mg/kg) Wistar rats (60%) i.p. inoculation of 300-600 mg/kg d-Phenylalanine (d-Pha) did not change the nociception (tail-flick test), but in morphine-resistant rats (40%) evoked a dose-dependent analgetic effect. In morphine-sensitive rats (40%) chronic morphine administration induced the tolerance and d-Pha injection evoked analgetic effect. Morphine injection just after d-Pha analgesia was over evoked analgetic effect in morphine-resistant and -tolerant rats. It is suggested that morphine-resistant rats have a congenital and morphine-tolerant rats an acquired high level of enkephalinase activity which blocked the morphine analgetic action.     

Characteristics of effects of mu-, delta-, and kappa-opioid agonists and enkephalinase inhibitor RB101 in rats of two inbred strains]

OBJECTIVE: In a attempt to avoid the potential drawbacks associated with sternotomy coupled with a desire for a smaller scar led us to investigate the transxiphoid approach without sternotomy. We present our preliminary experience and a comparison between the sternal and thoracic approaches. METHODS: From June 1996, at the Institut Cardiovasculaire Paris Sud, Massy, France (ICPS) and the Heart Institute, Sao Paulo, Brazil (HI) the transxiphoid approach was adopted for the correction of selected congenital cardiac defects. The xiphoid was resected through a 6 cm long vertical skin incision. With a special retractor the sternum was elevated cephalad and anteriorly. Closure of the defect was performed in the conventional manner. Twenty-six patients; 17 boys and 9 girls were entered into the study from representing 19 atrial septal defects (ASDs), 4 ventricular septal defects (VSDs) and 3 partial atrio ventricular septal defect (AVSDs). In addition at ICPS the transxiphoid approach for correction of ASD was compared to the thoracic and sternal approaches performed in the same period. RESULTS: Both the aortic cross clamp time as well as the duration of extracorporeal circulation were increased when compared to either standard sternotomy or thoracotomy approaches. There were no differences within the groups when comparing body surface area, amount of chest drainage or length of either ICU or hospital stay. However the patients in the transxiphoid group showed less pain and respiratory discomfort. CONCLUSION: Our initial experience with the transxiphoid approach without sternotomy confirms that it is a promising technique that can be considered an alternative to conventional sternotomy. The access is adequate for surgical procedures performed through a right atriotomy. The advantages include a better cosmetic scar, less surgical trauma, minimal respiratory discomfort and a potentially lower risk of infection. However cardiopulmonary bypass and cross clamp times are increased. There were no complications, and patient satisfaction was high.     

Behavioral and neuroendocrine reactivity to stress in the WKHA/WKY inbred rat strains: a multifactorial and genetic analysis

Genetic factors have been shown to influence the nature and the intensity of the stress responses. In order to understand better the genetic mechanisms involved, we have studied the behavioral and neuroendocrine responses to novel environments in the WKHA/WKY inbred strains and we have investigated the genetic relationships between these traits in a segregating F2 intercross. The animals were submitted to behavioral tests known to provide both indices of activity and fear (activity cages, open field and elevated plus-maze). The plasma levels of prolactin, ACTH, corticosterone, glucose and renin activity were determined after a 10-min exposure to novelty. Our results showed that WKHA rats, compared to WKYs, were more active in a familiar as well as in novel environments. They exhibited also less anxiety-related behaviors and lower neuroendocrine responses. A principal component analysis performed on the behavioral F2 results defined three independent factors: general activity, anxiety and defecation, none of them being correlated with the neuroendocrine measures. Thus this study suggests that these different responses to stress are independent components that may have distinct molecular bases.     

The ontogeny of morphological differences in the mandible in two inbred strains of mice

We have analyzed the postnatal ontogeny of the mandible of two inbred strains of mice (C3HeB and C57/BL) with conventional statistical analysis of area traits and with Euclidian Distance Matrix Analysis (EDMA). The relative contribution of the distal tooth-bearing part of the mandible to the area of the whole mandible decreases over time. The most prominent differences in shape between mice of 10 days and 25 days postnatal age are found in the lower posterior part of the mandible. Between angular and condylar process intramembranous ossification proceeds at a high rate and gradually fills the space between these two processes. The position of the proximal end of the molar tooth-row is relocated ventrally during this period. Morphological differences between C3H and C57 are most pronounced at 15 days postnatal age. Regions that discriminate best between the two strains change during development. While differences in the coronoid process separate the two groups clearly at 10 and 25 days postnatal age, no significant differences in the coronoid process are found at 20 days postnatal age. Similarly, masseter area shows significant differences at 15 and 25 days postnatal age, while C57 and C3H mice are equivalent for this trait at the other times. The same qualitative results are obtained by Euclidian Distance Matrix Analysis (EDMA): regions of major differences between strains are not consistent among ages. These results suggest that the ontogeny of morphological differences between closely related taxa is quite an erratic process; development of morphometric differences does not proceed smoothly and continuously. This unpredictable pattern of development of morphometric differences is expected if development of the mandible is tightly integrated by epigenetic and regulatory processes.     

Characterization of phenytoin-resistant kindled rats, a new model of drug-resistant partial epilepsy: comparison of inbred strains

PURPOSE: Previous work from our laboratory showed that amygdala-kindled Wistar outbred rats can be selected according to the increase of afterdischarge threshold (ADT) after phenytoin application. Animals that consistently do not respond to phenytoin (PHT) with an ADT increase (non-responders) are the first animal model of pharmacoresistant complex partial seizures. In this study, we determined the ability to respond to PHT in male kindled rats of different inbred strains. METHODS: The experiments were performed in fully kindled rats of five different inbred strains, Wistar-Kyoto, Lewis, Fischer 344, ACI, and Brown Norway. The response type of each rat was revealed by four consecutive PHT applications (75 mg/kg, i.p.) in fully kindled rats. RESULTS: PHT application resulted in plasma concentrations ranging from some 16 microg/ml in Lewis rats to 35 microg/ml in Fischer 344 rats, and in slight ataxia, most strongly in Fischer 344 rats. The rats of each strain did not show a homogeneous response to PHT. A significant increase of ADT was found after 86-97% of applications in Lewis, Wistar-Kyoto, and Fischer 344 rats. In contrast, Brown Norway rats responded in only 34% of experiments. This led to a considerable number of responders (i.e., consistent ADT increase by >20%) in Fischer 344, Wistar-Kyoto, and Lewis rats. The only strain revealing nonresponders (i.e., consistent lack of ADT increase by >20% with PHT treatment) was Brown Norway. CONCLUSIONS: Inbred strains, although genetically more homogenous than outbred strains, differ in their response to PHT. Brown Norway rats can offer advantages for further detailed investigation of the resistance to PHT in the kindling model of complex partial seizures.