A psychophysical study of the visual perception of “instantaneous” and “durable”

The perception of light stimulus duration as related to “instantaneous-durable” (I-D) threshold was analysed in experienced (class A) and experimentally naive (class B) subjects using a category judgement and a four response forced-choice method. As subjective luminance is directly dependent on duration (Bloch's law) for the brief stimulus presentations used in the experiments, it was necessary to eliminate the brightness cue in the I-D threshold measurements (luminance compensation curves). The passage of visual sensation from “instantaneous” to “durable” occurs at flash durations of 60–65 msec (class A) and 100–125 msec (class B). Certainty of perception of “durable” occurs at durations longer than 140 msec (class A) and 190 msec (class B).     

Analysis of caffeine: comparison of the manual enzyme multiplied immunoassay (EMIT), automated EMIT, and high-performance liquid chromatography procedures

Caffeine has been recommended for the treatment of apnea in newborn children. Most of the current methods for measurement of caffeine in newborns have used high-performance liquid chromatography (HPLC) because analysis can be performed on as little as 50 microliter of serum, an important factor when obtaining multiple blood samples for routine drug monitoring in infants and children. We evaluated the manual Syva enzyme multiplied immunoassay technique (EMIT) caffeine procedure and compared the assay results with our HPLC caffeine method. The EMIT procedure was also automated, and these results were compared with those of the manual and HPLC procedures. The 7-micrograms/ml calibrator was analyzed 20 times to establish within-run precision for the manual procedure. The mean +/- SD was 6.97 +/- 0.33, and the coefficient of variation (CV) was 4.80%. Reproducibility was tested by multiple analysis of the 11-micrograms/ml control. The mean +/- SD (CV) for the manual system was 11.3 +/- 0.45 (4%), n = 17; for the HPLC system, 10.58 +/- 0.89 (8.4%), n = 10; and for the automated system, 10.4 +/- 0.78 (7.5%), n = 12. Samples from 32 patients were analyzed by each of the above procedures. There was a good correlation among all three procedures. The correlation coefficient (r) for HPLC vs. manual EMIT was 0.98; for HPLC vs. automated EMIT, 0.97; and for automated EMIT vs. manual EMIT, 0.96. We conclude that the new Syva EMIT caffeine method is reliable and reproducible and can be applied to automated analysis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Time course of degeneration of the visual system induced by spontaneous glaucoma in the albino quail (Coturnix coturnix japonica)

The retinal projection of an imperfect albino quail mutant with a sex-linked recessive gene was examined 2 weeks-16 months post-hatch using various histological methods. During the first weeks the visual system was normal. Initial signs of buphthalmos, a form of spontaneous glaucoma, appeared between the 3d and 5th months. Its development induced a degeneration of the retinal projections according to a relatively precise sequence progressing from the mesencephalic tegmentum to the optic tectum, then from the pretectum to the thalamus. The data suggest that the degeneration of the optic axons results from their mechanical compression due to the increased intraocular pressure.     

Intravenous immunoglobulin in Diamond-Blackfan anaemia

Since immunological disorders have been demonstrated in patients with Diamond-Blackfan anaemia (DBA), intravenous immunoglobulins (IVIG) were administered to a 14-year-old girl with DBA and congenital malformations, previously treated with corticosteroids and blood transfusions. No therapeutic effect was observed.     

Long-term marrow culture in patients with aplastic anemia compared with marrow transplant recipients and normal controls.

Patients with severe aplastic anemia (SAA; n = 46) were studied in long-term bone marrow culture (LTBMC) systems and compared with allogeneic marrow transplant (BMT) recipients (n = 16) (within 30 days following BMT) and normal control patients (n = 12). SAA patients were divided in two groups: transfusion-dependent (Tx-D) SAA patients (group A; n = 15) and transfusion-independent (Tx-I) patients after treatment with antilymphocyte globulin (group B; n = 31). Cultures were analyzed at three levels: stromal layer (SL) formation (score: 0, no SL; 1, half confluent SL; and 2, confluent SL), number of nucleated cells in suspension, and growth of CFU-GM colonies. SL formation was rapid and complete in SAA patients, groups A and B (mean score on day 14: 1.3 and 1.4), similar to controls (mean score on day 14: 1.3), whereas an impairment of SL formation was seen in BMT recipients (mean score on day 14: 1.0). The number of nucleated cells in suspension increased significantly on day 7 of culture in controls (7.6-fold), significantly more than in BMT and SAA patients, and declined thereafter. Colony formation was also significantly increased on day 7 in Tx-I SAA patients, BMT recipients, and normal controls (4-, 5-, and 16-fold, respectively), lasting respectively 2, 3, and 4 weeks. Increments of colony formation were also obtained in Tx-D SAA patients, but in the first week of culture only. In conclusion: 1) a significant impairment of SL formation was seen in BMT recipients, but not in SAA patients; 2) a significant increment of granulocyte-macrophage colony-forming units (CFU-GM) growth can be obtained in patients with marrow failure early after starting long-term culture; 3) the number of CFU-GM grown in these culture conditions from Tx-I SAA patients parallels the number of progenitors from early post-BMT recipients; and 4) progenitor cells from Tx-D SAA patients are not only reduced in numbers, but also exhibit a poor ability to survive in LTBMC.     

A radioautographic study of retinal projections in Type I and Type II lizards

The retinofugal projections of 5 species (Acanthodactylus boskianus, Scincus scincus, Tarentola mauritanica, Uromastix acanthinurus and Zonosaurus ornatus) belonging to 5 different families of Type I and Type II lizards have been examined by means of the radioautographic method. In the 5 species the retinal ganglion cells project to the contralateral hypothalamus (nucleus suprachiasmaticus), thalamus (nucleus geniculatus lateralis pars ventralis, nucleus geniculatus lateralis pars dorsalis), pretectum (nuclei lentiformis mesencephali, geniculatus pretectalis, postero-dorsalis griseus tectalis), tectum opticum (layer 2 to layer 6 of the stratum griseum et fibrosum superficiale) and tegmentum mesencephali (nucleus opticus tegmenti). Ipsilateral optic fibers were never observed in Uromastix acanthinurus, whereas an uncrossed quota was visible in both nucleus geniculatus lateralis pars dorsalis and nucleus postero-dorsalis in the other species. An ipsilateral retinotectal projection was observed only in Tarentola mauritanica. With the exception of the nucleus griseus tectalis the contralateral optic centers identified in this material have to a large extent been observed in other reptiles belonging to the different orders. The presence in reptiles of a general pattern of contralateral visual projections indicates that these were established very clearly in the course of evolution. Similarities become apparent when this plan is compared with that observed in birds. In marked contrast the ipsilateral component in reptiles is unstable and mutable in nature. This ipsilateral retinotectal projections do not appear to be a feature restricted to Type I lizards. On the other hand, the presence of this optic component cannot be linked solely to nocturnal habits.     

Failure of naloxone to affect initial and acquired tolerance to ethanol in rats

The effects of naloxone on the initial sensitivity to ethanol and the subsequent changes in tolerance induced by prior ethanol treatment were studied in rats by using the drinking test for assessing behavioral effects. Naloxone (N) was administered concurrently with ethanol (E) in either 5 successive single doses spaced at 2-day intervals (Experiment 1) or during 4 days of chronic i.v. infusion (E. 9 g/kg, N: 9 mg/kg in 6 injections per day, Experiment 2). Both treatments produced an increase in nervous tolerance toward ethanol. However naloxone was found to exert no effect on either initial or acquired tolerance toward ethanol. The results are discussed in terms of possible relations between the CNS mechanisms involved in tolerance to morphine and ethanol.