Naloxone-reversible analgesia as a result of stimulation of the habenula in the rat

Electrical stimulation of rat habenular complex induces analgesia, evaluated by the tail-flick test, dependent on intensity of stimulation with a long post-effect, that is reversible by naloxone and without behavior effects at less that 400 mA. Bilateral destruction of habenula fails to provoke hyperesthesia but causes more marked long-term tolerance effects than in controls. Anatomy suggests that the habenula activates an inhibitory descending system in the spinal cord with a probable relay in the dorsal raphe and involving an endogenous opioid-dependent stage.     

Identification of single dissimilar odors is achieved by humans with a single sniff

The duration that a single odor needs to be sniffed for identification was determined for 18 humans. A hot wire anemometer and an oscilloscope were used to monitor the duration, volume and inhalation rate of sniffs. In Experiment 1 subjects used 1, 3 or 5 natural sniffs, or an unlimited number of natural sniffs to sample seven dissimilar single odors of moderate perceived intensity, and demonstrated that each odor could be identified with a single sniff. In Experiment 2 subjects demonstrated that each of the odors could be identified with the shortest sniff (0.42 sec) they could physically achieve. In Experiment 3 tests with two of the odorants at several concentrations showed that sniff duration influences identification over a narrow range of concentrations that is just above the recognition threshold. These results together with earlier data that described the optimum conditions for the detection of an odor and the perception of odor intensity, provide information that is necessary for the development of a standard olfactometer and standard methods for human olfactory measurements.     

Giant axonal neuropathy: central abnormalities demonstrated by evoked potentials

Previous studies of giant axonal neuropathy have reported clinical and pathological findings that indicate involvement of the central nervous system. We studied 3 boys with giant axonal neuropathy, who were 14 to 16 years of age, using auditory, visual, and somatosensory evoked potentials. Absence of waveforms and prolongation of peak and interwave latencies were found. Abnormalities were noted in all modalities. The auditory brainstem evoked response in particular indicated a significant increase in brainstem conduction time. These studies add clinical neurophysiological confirmation of the central nervous system involvement in this disorder and may also provide a means of quantitative evaluation of its progression.     

Etiological heterogeneity in Hodgkin's disease: HLA linked and unlinked determinants of susceptibility independent of histological concordance

Forty-one multiplex families, from published sources and new data from the National Cancer Institute, segregating for Hodgkin's disease and HLA, have been studied. A reanalysis of these data strongly suggests a recessive mode of inheritance for susceptibility to Hodgkin's disease. The HLA haplotype sharing data between affected relatives demonstrate that approximately 60% of cases in multiplex families are due to an HLA-linked susceptibility gene, the remaining 40% being due to other familial factors. The data clearly support the hypothesis of etiological heterogeneity for Hodgkin's disease, with both HLA-linked and HLA-unlinked factors being responsible. Finally, there is an increased concordance of histological types between affected relatives, but this concordance seems independent of HLA sharing.