Surface areas of the septum pellucidum, corpus callosum and the brain were measured from mid-saggital slices obtained with magnetic resonance imaging in 18 patients with schizophrenia and an equal number of normal volunteers. The patients showed larger septa and septo-brain ratios. These indices correlated with age in both patients and controls. In the patients, septal area also correlated with duration of illness. Changes in the septum pellucidum were unrelated to the intensity of positive and negative symptoms of schizophrenia. The patients had significantly longer corpora callosa, but the two groups did not differ on its size or the ratio between the latter and the mid-saggital slice area. Dimensions of the corpus callosum did not correlate with age, duration of the illness or positive and negative symptoms of schizophrenia. The anteroposterior elongation of the structure seemed to accompany enlargement of the septum pellucidum.
The hairless guinea pig (HGP) is used by our laboratory to model the human cutaneous response to sulfur mustard (HD), bis(2-chloroethylsulfide), exposure. We determined the HD content in the skin of HGP after a 7-min exposure to vapors saturated with a mixture of HD and 14C-HD. Concentration/time (CT) values in the range of 2 micrograms/cm2/min were determined by counting skin 14C disintegrations per min (dpm) in animals euthanized immediately after exposure. These values are similar to human penetration rates obtained by other investigators. A rate curve monitoring the reduction in skin 14C dpm was developed for animals euthanized between 0 and 24 hr post- exposure. This curve showed the greatest change after 1 hr. The epidermal (62%) to dermal (38%) ratio of 14C at 24 hr was measured for two animals. We saw no site preference for HD penetration among the 8 sites used. The 14C content of template adhesive tape was determined to follow HD distribution. These results contribute to a better understanding of the cutaneous response to HD in the HGP model.
Background/aims: The euthymic hairless guinea pig was the animal model of choice at this laboratory for vesicant injury research. The supply of these animals, however, was interrupted in 1993 by an outbreak of Lisferia monocyfogenes at the commercial supplier's breeding facility, thereby forcing a search for alternative animal models. This report describes the development of a weanling pig model for use in evaluating the severity of skin lesions induced by sulfur mustard [bis(2‐chloroethyl)sulfide; SM] using a variety of bioengineering techniques. These methods include reflectance colorimetry (erythema response), high frequency ultrasound imaging (edema response) and a modified dermal torque meter procedure to test for Nikolsky's sign (damage at the dermal‐epidermal junction). The time course and exposure time‐dependence of SM‐induced lesions for these parameters were characterized in this model and compared with previous results in the haired and hairless guinea pig. Methods: Six male Yorkshire Cross pigs (7–10 kg) were used in this study. The hair on the dorsal surface of each animal was shaved the afternoon prior to SM exposure. Twenty‐four dorsal skin sites on each pig were exposed to saturated SM vapor (1.4 mg/l) using 14‐mm diameter vapor cups for 0 (control), 5, 10, 15, 20, or 25 min, with four sites per exposure level. Control and exposure sites were rotated to prevent site‐specific biases. Lesions were evaluated for erythema (reflectance colorimeter) at 4, 6, 12, 24 and 48 h post‐exposure, and for edema (high frequency ultrasound) at 6, 12, 24, and 48 h post‐exposure. Evaluations for Nikolsky's sign and histopathology were conducted at 48 h post‐exposure. Results: Maximum erythema responses occurred at 24 h postexposure for all SM exposure times (5, 10, 15, 20 and 25 min). The overall maximum response occurred with a 15‐min SM vapor exposure at 24 h post‐exposure. Exposures longer than 15 min did not induce significantly greater erythema at any of the time points examined. The earliest time point at which significant edema was noted was at 12 h for the 15‐ and 25‐min SM vapor groups. Maximum edema occurred at 48 h following a 15‐min exposure. No significant increase in edema was noted at any observation time point with exposures longer than 15 min. All sites showed a weakening of the dermal‐epidermal junction (positive Nikolsky's sign) 48 h after a 15‐min or longer SM vapor challenge. The histologic severity of the lesions did not significantly worsen as the vapor exposure was increased beyond 15 min. (Following a 15‐min SM exposure, incidences of epidermal necrosis, pustular epidermitis, microblisters and vascular damage had reached 100%, with maximum mean severity scores.) The weanling pig is more resistant to the effects of SM vapor than either the haired or hairless guinea pig, showing a delayed response and requiring a longer exposure time to generate the same (quantitative and qualitative) response in erythema, Nikolsky's sign and microblister formation. SM vapor‐induced edema formation in the wean...
The reduction of vanadium(V) by titanium(III) in acidic chloride or perchlorate solutions occurs in three distinct consecutive steps; the third was present only with V(V) in excess, while the first two were studied with excess Ti(III). The pseudofirst-order rate constant for the first step follows the equation kl=kr + kf [Ti(III)], where kf = a/(K& + [H+¡) and Ka is the acid dissociation constant of Ti37. For the second step, k2 = £>[Ti(III)] /(l + K[Ti(III)]), where the value of K as well as its [H7] dependence agrees identically with the ratio k¡lkr from the first step, and b = d/(e[H7] + [H7]2). The third step which is identified as the formation of a Ti(IV)-V(V) binuclear complex follows the equation -d In [Ti(IV)] /dr = (f + g[H7] + A[H7]2)[V(V)] xs. Mechanisms for these reactions are presented and discussed. Evidence is also presented for the existence of a dimeric species in Ti(III) solutions.
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