Hand-to-Face Remapping But No Differences in Temporal Discrimination Observed on the Intact Hand Following Unilateral Upper Limb Amputation

Unilateral major limb amputation causes changes in sensory perception. Changes may occur within not only the residual limb but also the intact limb as well as the brain. We tested the hypothesis that limb amputation may result in the detection of hand sensation during stimulation of a non-limb-related body region. We further investigated the responses of unilateral upper limb amputees and individuals with all limbs intact to temporally based sensory tactile testing of the fingertips to test the hypothesis that changes in sensory perception also have an effect on the intact limb. Upper extremity amputees were assessed for the presence of referred sensations (RSs)—experiencing feelings in the missing limb when a different body region is stimulated, to determine changes within the brain that occur due to an amputation. Eight of 19 amputees (42.1%) experienced RS in the phantom limb with manual tactile mapping on various regions of the face. There was no correlation between whether someone had phantom sensations or phantom limb pain and where RS was found. Six of the amputees had either phantom sensation or pain in addition to RS induced by facial stimulation. Results from the tactile testing showed that there were no significant differences in the accuracy of participants in the temporal order judgment tasks (p = 0.702), whereby participants selected the digit that was tapped first by a tracking paradigm that resulted in correct answers leading to shorter interstimulus intervals (ISIs) and incorrect answers increasing the ISI. There were also no significant differences in timing perception, i.e., the threshold accuracy of the duration discrimination task (p = 0.727), in which participants tracked which of the two digits received a longer stimulus. We conclude that many, but not all, unilateral upper limb amputees experience phantom hand sensation and/or pain with stimulation of the face, suggesting that there could be postamputation changes in neuronal circuitry in somatosensory cortex. However, major unilateral limb amputation does not lead to changes in temporal order judgment or timing perception tasks administered via the tactile modality of the intact hand in upper limb amputees.

Where You Look Matters for Body Perception: Preferred Gaze Location Contributes to the Body Inversion Effect

The Body Inversion Effect (BIE; reduced visual discrimination performance for inverted compared to upright bodies) suggests that bodies are visually processed configurally; however, the specific importance of head posture information in the BIE has been indicated in reports of BIE reduction for whole bodies with fixed head position and for headless bodies. Through measurement of gaze patterns and investigation of the causal relation of fixation location to visual body discrimination performance, the present study reveals joint contributions of feature and configuration processing to visual body discrimination. Participants predominantly gazed at the (body-centric) upper body for upright bodies and the lower body for inverted bodies in the context of an experimental paradigm directly comparable to that of prior studies of the BIE. Subsequent manipulation of fixation location indicates that these preferential gaze locations causally contributed to the BIE for whole bodies largely due to the informative nature of gazing at or near the head. Also, a BIE was detected for both whole and headless bodies even when fixation location on the body was held constant, indicating a role of configural processing in body discrimination, though inclusion of the head posture information was still highly discriminative in the context of such processing. Interestingly, the impact of configuration (upright and inverted) to the BIE appears greater than that of differential preferred gaze locations.

CAML regulates Bim-dependent thymocyte death

Appropriate control of apoptosis during T lymphocyte differentiation is critical for destruction of T cells bearing potentially autoreactive or useless immuno-receptors and for survival of those T cells bearing antigen receptors that may recognize foreign proteins. Despite the well-established importance of thymocyte survival, the exact signals regulating thymocyte apoptosis have not been fully elucidated. Here, we show that thymocytes lacking the endoplasmic reticulum protein calcium-modulating cyclophilin ligand (CAML) failed to undergo normal T-cell development and exhibited dramatically increased rates of apoptosis. In vitro, CAML-deficient thymocytes accumulated high levels of reactive oxygen species (ROS) and underwent abnormally accelerated death in response to several cytotoxic stimuli, including treatment with etoposide, cytokine deprivation, or Fas ligation. Although neither p53 deletion nor loss of Fas rescued the survival and continued development of CAML-deficient thymocytes, removal of the pro-apoptotic BH3-only Bcl-2 family member Bim significantly restored their survival. This work reveals CAML to be a critically important regulator of ROS- and Bim-dependent thymocyte death.

Chemical reactivity, cytotoxicity, and mutagenicity of chloropropanones

Studies were conducted to assess the in vitro toxicity of three chloropropanones: monochloropropanone (MCP), 1,1-dichloropropanone (1,1-DCP), and 1,3-dichloropropanone (1,3-DCP). Chloropropanones reacted directly with reduced glutathione (GSH) in sodium phosphate buffer at pH 7.4. All chloropropanones were cytotoxic to suspensions of male rat hepatocytes in a concentration range of 0.5-10 mM. Cytotoxicity was preceded by rapid decline in cellular GSH levels. Mutagenic potencies among the chloropropanones in Salmonella typhimurium bacteria differed greatly. 1,3-DCP was mutagenic in the nanomole range, 1,1-DCP was weakly mutagenic in the micromole range, and MCP was not mutagenic. Mutagenicity of the dichloropropanones was evident without metabolic activation. These results suggest that the three chloropropanones may, in part, be directly cytotoxic but only 1,3-DCP and 1,1-DCP are directly mutagenic.

Analysis of polysorbate and its polyoxyethylated metabolite

Polysorbates are used as emulsifiers in a number of pharmaceuticals and have been implicated as the possible toxic agent in the neonatal vitamin supplement, E-Ferol. In the investigation of the toxicity of this compound, it was necessary to find a method to separate and quantitate polysorbate and its polyoxyethylated metabolite from biological fluids. A high-performance liquid chromatography method was developed which combines the use of a 500 A mu Styragel size exclusion column with an ammonium cobaltothiocyanate complexation column and detection at 620 or 320 nm. The detection limit is approximately 5 micrograms. The method was used to demonstrate that polysorbate was metabolized in vitro by hepatocytes and that the urinary metabolite in humans is comparable to that produced by the rat.

Determination of polysorbate in ascites fluid from a premature infant

A method is described for the determination of poly(oxy-1,2-ethanediyl)oligomers in body fluids using ammonium cobaltothiocyanate complexation in conjunction with high pressure liquid chromatography and visible spectrophotometry. Analysis of peritoneal fluid from a baby given E-ferol, a vitamin E supplement, revealed levels as high as 100 micrograms/mL polysorbate.

Human conjunctival surface mucins: a quantitative study of normal and diseased (KCS) tissue

The architecture and distribution of surface mucins were studied qualitatively and quantitatively by transmission electron microscopy in ruthenium red stained biopsies of the human conjunctiva. Six control specimens were compared with three from early keratoconjunctivitis sicca (KCS) and with three specimens from severe KCS cases. The area of the ruthenium red/OsO4/mucin reaction product on the conjunctival epithelial surface was measured by image analysis and the values were expressed in micron2 per micron length of epithelium. The total area of surface mucins was differentiated from the narrow zone of mucins in close contact with the microplicae. The value for total mucins in two cases of early KCS was higher (0.4 micron2/micron) than the control range (0.1-0.3 micron2/micron) due to the presence of large clumps of mucins on the surface. The values for microplical mucins in early and severe KCS were within the control range, but were an overestimate owing to the presence of abnormal structures, e.g. vesicles, and abnormal clumps on the surface. This morphometric technique has limitations, but with appropriate material it might be a useful tool for the identification of conjunctival surface mucins.