Single-cell responses to three-dimensional structure in a functionally defined patch in macaque area TEO

Both dorsal and ventral visual pathways harbor several areas sensitive to gradients of binocular disparity (i.e., higher-order disparity). Although a wealth of information exists about disparity processing in early visual (V1, V2, and V3) and end-stage areas, TE in the ventral stream, and the anterior intraparietal area (AIP) in the dorsal stream, little is known about midlevel area TEO in the ventral pathway. We recorded single-unit responses to disparity-defined curved stimuli in a functional magnetic resonance imaging (fMRI) activation elicited by curved surfaces compared with flat surfaces in the macaque area TEO. This fMRI activation contained a small proportion of disparity-selective neurons, with very few of them second-order disparity selective. Overall, this population of TEO neurons did not preserve its three-dimensional structure selectivity across positions in depth, indicating a lack of higher-order disparity selectivity, but showed stronger responses to flat surfaces than to curved surfaces, as predicted by the fMRI experiment. The receptive fields of the responsive TEO cells were relatively small and generally foveal. A linear support vector machine classifier showed that this population of disparity-selective TEO neurons contains reliable information about the sign of curvature and the position in depth of the stimulus. NEW & NOTEWORTHY We recorded in a part of the macaque area TEO that is activated more by curved surfaces than by flat surfaces at different disparities using the same stimuli. In contrast to previous studies, this functional magnetic resonance imaging-defined patch did not contain a large number of higher-order disparity-selective neurons. However, a linear support vector machine could reliably classify both the sign of the disparity gradient and the position in depth of the stimuli.

Blockade of the orexin receptors in the CA1 region of hippocampus decreased the lateral hypothalamic-induced antinociceptive responses in the model of orofacial formalin test in the rats

The role of hippocampus and lateral hypothalamus (LH) in modulation of formalin-induced nociception has been established. The present study aims to examine the role of orexin receptors in the Cornu Ammonis 1 (CA1) region of hippocampus in modulation of the LH-induced antinociception in the orofacial formalin test. Male Wistar rats were unilaterally implanted with two cannulae into the LH and CA1. Intra-LH microinjection of carbachol was done 5min after intra-CA1 administration of SB-334867 (OX1R antagonist) or TCS OX2 29 (OX2R antagonist). After 5min, 50μl of 1% formalin was subcutaneously injected into the upper lip for inducing the nociceptive behaviors. Solely intra-LH administration of carbachol reduced early and late phases of formalin-induced orofacial nociception in a dose-dependent manner. The antinociception evoked by intra-LH injection of carbachol (0.5μl of 250nM carbachol) was antagonized by intra-CA1 administration of 0.5μl of 3, 10 and 30nM solutions of SB-334867 or TCS OX2 29 during the early and late phases of orofacial formalin test. This effect was more remarkable during the late phase in comparison to the early phase. In addition, anti-analgesic effect of SB-334867 was more than TCS OX2 29 during the early and late phases. The results suggest the interpretation that a neural pathway from the LH to the CA1 probably contributes to the modulation of formalin-induced orofacial nociception through recruitment of both CA1 orexin receptors. Clinical studies are recommended to study the probable effectiveness of orexinergic system in modulation of the orofacial nociceptive responses.

The comparison of the effects of acute and repeated morphine administration on fast synaptic transmission in magnocellular neurons of supraoptic nucleus, plasma vasopressin levels, and urine volume of male rats

The activity of the magnocellular neurons (MCNs) of supraoptic nucleus (SON) is regulated by a variety of excitatory and inhibitory inputs. Opioids are one of the important compounds that affect these inputs at SON synapses. In this study, whole-cell patch clamp recording of SON neurons was used to investigate the effect of acute and repeated morphine administration on spontaneous inhibitory and excitatory post synaptic currents (sIPSCs and sEPSCs) in MCNs. While acute bath application of morphine to brain slice of intact rat produced an increase in sEPSCs frequency and a decrease in sIPSCs frequency, repeated in-vivo administration of morphine produced opposite effect. Moreover, repetitive i.c.v. administration of morphine for three consecutive days caused significant increase in urine volume, but had no significant alteration in water consumption compared to control group. The increase in urine volume was consistent with a significant decrease in plasma arginine vasopressin (AVP) levels after repetitive i.p. morphine administration. The results suggest that acute administration of morphine stimulates whereas repeated administration of morphine inhibits the MCNs. Morphine-induced MCN inhibition could result in diminished plasma AVP levels and eventually an increase in urine volume of rats.

Antibiotic-coated pins for prevention of pin-tract infection: a rabbit study

PURPOSE. To evaluate the efficacy of antibiotic-coated pins for prevention of pin tract infection in a rabbit model. METHODS. 10 rabbits were divided into 2 groups. A unilateral external fixator was applied to the tibia with 4 self-taping 1.8-mm pins. In the test group, pins were coated with hydroxyapatite and antibiotic. In the control group, pins were not coated. All pins were then placed in Staphylococcus aureus- containing media. At postoperative day 5, all 40 pin sites were subcutaneously inoculated with S aureus. The sites were clinically examined for signs of pin tract infection. Nine days later, a piece of soft tissue around the pin site was harvested for microbiologic examination. RESULTS. In the test group, all except one pin sites appeared clean and without clinical infection, and the culture media remained clear. In the control group, all pin sites showed evidence of clinical infection and yielded positive cultures, and the culture media became dark indicating growth of S aureus. CONCLUSION. Antibiotic-coated pins were effective in preventing pin tract infection.

Relationship between consultation length and rational prescribing of drugs in Gorgan City, Islamic Republic of Iran

Doctors with longer consultation times tend to diagnose illnesses more precisely, prescribe fewer drugs and present better health advice to their patients. The aim of this study was to measure the average consultation time of general practitioners in Gorgan, Islamic Republic of Iran and to investigate the factors affecting consultation length, especially in relation to rational prescribing of drugs. Data were collected on 620 patient consultations with 62 randomly selected general practitioners. Mean consultation length was 6.9 (SD 2.6) minutes. Patient factors that were significantly associated with a longer mean duration of consultation time were: higher number of health problems, older age and fewer items of previously used drugs. Physician factors that were significantly associated with a longer mean consultation time were: younger age, higher numbers of items prescribed and injectable drugs prescribed, frequency of interruptions and higher workload.

Rat xenograft chondrosarcoma development by human tissue fragment

Chondrosarcoma is one of the most difficult types of cancers to diagnose and treatment. Therefore, the development of a reliable animal model for chondrosarcoma would be a helpful tool to study of the tumor's growth and progression.

AIM

We conducted this study to develop a chondrosarcoma on rat by graft of human chondrosarcoma tumor tissue.

METHODS

Fourteen male Sprague-Dawley rats equally divided in xenograft-implanted and control groups. On the lateral side of the right femur distal 1/3, 5 mm incision was done on the skin after animal anesthesia. Then, was drilled 3 mm on the bone and implanted the xenograft in the bone. Radiography was taken from the operated femur weekly until the fourth week and monthly for 3 months. Four animals of each group were sacrificed after 4 weeks of operation; femur was harvested for histopathological study.

RESULTS

Radiological images showed sclerotic area on the implanted bone after 4 weeks of operation. Sections from tumoral areas reveal cartilage forming hypercellular neoplastic tissue with lobular pattern of growth and foci of adjacent tissue invasion such as bone trabeculas and bone marrow.

CONCLUSION

the present study showed that rat xenograft chondrosarcoma can develop by human chondrosarcoma fresh tissue fragments.

Repeated administration of nicotine attenuates the development of morphine tolerance and dependence in mice

Clinical use of morphine in pain management is a controversial issue. Both nicotine and morphine are widely abused. So, investigating the interaction between nicotinic and opioid receptors is of great interest to both basic mechanistic and clinical view. We investigated the influence of repeated administration of nicotine on the development of morphine tolerance and dependence. Adult male albino mice were rendered dependent on morphine by subcutaneous (s.c.) injections three times daily for 3 days. Repeated intraperitoneal (i.p.) injection of nicotine (0.001-2 mg/kg) or saline (1 ml/kg) was performed 15 min prior to each morphine injection. Maximal possible effect (MPE%) of morphine (50 mg/kg; s.c.) was used on the fourth day as an index for the development of tolerance. Likewise, to assess the occurrence of dependence in drug-treated mice, naloxone (5 mg/kg; i.p.) was injected 2 h after the last dose of morphine. Repeated nicotine administration significantly attenuated the development of tolerance in a dose-dependent manner whereas it significantly decreased withdrawal jumping behavior in a biphasic profile (V-shape) manner. Furthermore, the central nicotinic receptor antagonist mecamylamine (0.01-0.1 mg/kg; i.p.) neither the peripheral nicotinic receptor antagonist hexamethonium (0.01 and 0.1 mg/kg; i.p.) nor the muscarinic receptor antagonist atropine (2.5-10 mg/kg; i.p.), dose-dependently antagonized both the inhibition of withdrawal jumping as well as increase in MPE% which was produced by repeated nicotine administration (0.1 mg/kg; i.p.). On the other hand, 3 days of solely nicotine treatment resulted in significant jumping behavior precipitated by naloxone after single morphine injection on the test day. The data suggests that the inhibitory effect of nicotine on the morphine tolerance and dependence is mediated by central nicotinic receptors and there is a cross-dependence between nicotine and morphine.