Memory disorders as a function of traumatic brain injury. Word completion, recall of words and actions

The memory performance of a group with traumatic brain injury and a matched control group was assessed using the following methods (a) word completion, (b) immediate free, final free and final cued recall of words and (c) immediate free and final free recall of subject-performed tasks (SPTs) and SPTs without motor action (SPTs-WA). The brain-injured (BI) group was significantly inferior relative to the control group in all recall tests except immediate free recall of words. No difference was revealed in the word completion test. The BI-group benefitted less by cues presented either at retrieval (final cued recall of words) or at the time of encoding already built-in in the stimulus (SPTs and SPTs-WA). The results were discussed in terms of the neuropathological background of the patients in the BI-group suggesting that frontal dysfunction could play a critical role. When comparing the tests within the BI-group, however, the performance was better when cues were present and especially so for long-term memory. Motor activity also facilitated long-term memory. Finally, an attempt was made to specify conditions for guidance in the construction of training programmes.     

Iterative versus filtered backprojection reconstruction for statistical parametric mapping of PET activation measurements: a comparative case study.

The significance of task-induced cerebral blood flow responses, assessed using statistical parametric mapping, depends, among other things, on the signal-to-noise ratio (SNR) of these responses. Generally, positron emission tomography sinograms of H(2)(15)O activation studies are reconstructed using filtered backprojection (FBP). Alternatively, the acquired data can be reconstructed using an iterative reconstruction procedure. It has been demonstrated that the application of iterative reconstruction methods improves image SNR as compared with FBP. The aim of this study was to compare FBP with iterative reconstruction, to assess the statistical power of H(2)(15)O-PET activation studies using statistical parametric mapping. For this case study, PET data originating from a bimanual motor task were reconstructed using both FBP and maximum likelihood expectation maximization (ML-EM), an iterative algorithm. Both resulting data sets were statistically analyzed using statistical parametric mapping. It was found, with this dataset, that the statistical analysis of the iteratively reconstructed data confirm the a priori expected physiological response. In addition, increased Z scores were obtained in the iteratively reconstructed data. In particular, for the expected task-related response, activation of the posterior border of the left angular gyrus, the Z score increased from 3.00 to 3.96. Furthermore, the number of statistically significant clusters doubled while their volume increased by more than 50%. In conclusion, iterative reconstruction has the potential to increase the statistical power in H(2)(15)O-PET activation studies as compared with FBP reconstruction.     

Studies of mouse polyoma virus infection. II. Virus stability

Mouse polyoma virus was stored at 4° and –60°C. for 8 weeks without any loss in hemagglutination or infectivity titer; storage at 37° for 8 weeks reduced infectivity titer by approximately 2.5 log₁₀ units. Repeated freezing and thawing of infectious tissue culture fluid had no effect on virus titer. The stability of the virus to storage for 1 week at 4°C. was unaffected by suspension of infected tissue culture fluid in saline, demineralized distilled water, or 5 per cent horse serum in Eagle's basal medium. Heating the virus for 30 minutes at 60°C. had no effect on infectivity and hemagglutination titers. Heating at 65°C. for 30 minutes produced a 3 log unit loss of infectivity and a 4-fold decline in HA titer, and heating at 70°C. for 30 minutes usually produced complete inactivation of infectivity and HA. The virus was resistant to ultraviolet irradiation; ultraviolet irradiation for 2 hours caused a 4 log unit decrease in infectivity titer without affecting the HA titer. The virus was resistant to exposure to 2 per cent phenol and 50 per cent ethyl alcohol but was inactivated by 100 per cent ethyl alcohol, and ethyl alcohol-iodine mixtures. Lyophilization had no effect on the stability of the virus.     

Pharmacokinetics of heparin. II. Studies of time dependence in rats.

The purpose of this investigation was to determine whether the time course of heparin activity (bioassayed heparin concentration) in plasma of rats during and after constant rate i.v. infusion of heparin can be predicted from the pharmacokinetic characteristics of a single i.v. bolus dose of heparin administered to the same animals. Five rats received a rapid i.v. injection of heparin, 320 to 517 U/kg, and on the following day, an i.v. infusion of heparin, 2.7 to 4.0 U/min/kg, for 10 to 11 hr. Heparin activity in plasma at the end of the infusion was about twice as high as predicted on the basis of the total clearance of the bolus dose. Even though the maximum heparin activity immediately after the bolus dose and at the end of the infusion were similar, the biologic half-life of heparin at the end of the infusion was about twice as long as that of the bolus dose. Apparently, the pharmacokinetics of heparin are time dependent. This may explain, at least in part, the clinical observation that heparin infusion rate must often be reduced after the initial days of therapy.     

Memory functioning in hemiplegics: a neuropsychological analysis of the Wechsler Memory scale.

The Wechsler Memory Scale was administered to 60 hemiplegics and 30 amputees who were matched by age, education, and sex. The results indicated that the orientation subtest has diagnostic value in discriminating between left- and right-sided brain damage in patients and that the right hemisphere may play a proportionately larger role for temporal orientation. The mental control and digits backward subtests seem to be measuring a composite of different cortical functions which are not represented equally in both cerebral hemispheres. Optimal performance on these tests requires interhemispheric integration among these cortical functions. Unilateral damage to either side of the brain would interfere with a special part of the composite function subserved by the damaged hemisphere and produce comparable detrimental effects on performance. The logical memory, digits forward, and associate learning subtests measure memory functions which are equipotentially represented in both hemispheres. Damage to either side of the brain would have no effect on the performance of these tasks. In general, the neuropsychological analysis suggests that the Wechsler Memory Scale has diagnostic value in assessing short-term memory impairment in brain damaged patients. However, memory quotient obtained by summing the total subtest scores has very little value in discriminating between left- and right-sided brain lesions.     

Salsalate in the treatment of rheumatoid arthritis: a double-blind clinical and gastroscopic trial versus piroxicam. II. Endoscopic evaluation

A double-blind, double-dummy controlled study to compare the clinical efficacy and gastric tolerability of salsalate and piroxicam in the treatment of rheumatoid arthritis was performed. A total of 23 patients were treated with 1.5 g salsalate twice daily and 20 with 20 mg piroxicam (after the evening meal) for 4 weeks. Patients were submitted to gastroscopy at the start and end of treatment; only patients who presented a normal baseline gastroscopy were admitted to the trial. At the end of the planned treatment period, a statistically significant improvement of all clinical variables was observed in both treatment groups, the difference between the two drugs not being statistically significant. Five of 20 (25%) piroxicam treated patients and only 2/19 (11%) salsalate treated patients showed gastric lesions at final endoscopy. No relationship was found between dyspeptic symptoms and endoscopic lesions. The results show that salsalate and piroxicam have equal efficacy in relieving arthritic symptoms, but salsalate causes fewer gastric lesions.     

Studies of the plasmin system. II. Inhibition of plasmin by serum or plasma

The inactivation of purified plasmin by serum or plasma was studied using a caseinolytic assay for determination of plasmin. On the basis of kinetic evidence, the presence of two inhibitors in normal human or guinea pig serum or plasma is suggested. The first reacts immediately at any temperature, but is easily dissociable and does not combine with plasmin in a fixed ratio. The second combines more slowly with plasmin at a rate which depends on temperature and on the concentration of both plasmin and inhibitor. There is a fixed ratio of reaction between plasmin and the second inhibitor and the combination does not readily dissociate. There is sufficient of the "slow" inhibitor in normal plasma to inactivate more than 30 times its own content of potential plasmin. The presence of suitable substrate for plasmin tends to reverse the combination with "immediate" inhibitor and to stop the further action of "slow" inhibitor.     

Studies on nonprecipitating antibody. II. Circulating antibody-antigen complex following repeat injections of antigen

Reinjection of antigen into immunized rabbits usually results in an immediate increase of circulating antibody-antigen complex. This immediate formation of complex seems to depend upon the presence of non-precipitating antibody before reinjection. The complex disappears by the 2nd day after reinjection and reappears between the 4th to 7th day. This is earlier than its first appearance after a primary injection and may indicate an anamnestic response of the non-precipitating antibody responsible for the formation of circulating antibody-antigen complex.     

The glomerular mesangium. II. Studies of macromolecular uptake in nephrotoxic nephritis in rats

These studies were designed to explore the effects of nephrotoxic serum (NTS) in rats on the uptake and processing by the glomerular mesangium of intravenously administered protein macromolecules (radiolabeled aggregated human IgG, [125I]AHIgG). Measurements of [125I]AHIgG levels in preparations of isolated glomeruli correlated well with qualitative estimates of glomerular IgG deposition seen by immunofluorescent microscopy. Rats given 2 ml NTS received 25 mg/100 g body wt [125I]AHIgG 48 h later and were sacrificed at varying time intervals thereafter. NTS-treated animals demonstrated a marked increase in glomerular uptake of [125I]AHIgG as compared with concurrent controls but a normal ability to clear [125I]AHIgG from the mesangium over 72 hr. Animals given 1.0, 0.5, and 0.25 ml NTS had neither proteinuria nor significant light microscopic changes, yet had increased uptake of [125I]AHIgG of 4.4, 3.0, and 2.1 times control values, respectively at 8 h after the infusion of aggregates. Rats given 1 ml NTS and 12.5, 6.25, and 3.125 mg [125I]AHIgG/100 g body wt had increased glomerular uptake at 8 h, but there was, within both NTS and control groups, a disproportionate decrease in uptake at lower [125I]AHIgG doses. Rats given cobra venom factor (CoF) followed by a NTS shown to be complement dependent (proteinuria reduced by prior complement depletion with CoF) had less mesangial [125I]AHIgG uptake than NTS controls but greater uptake compared with normal controls. CoF itself had no effect on mesangial or reticuloendothelial system [125I]AHIgG uptake. These studies demonstrate a striking change in glomerular mesangial activity after fixation of nephrotoxic antibodies to the glomerular basement membrane, even in the absence of proteinuria and suggest that subtle alterations of the filtration surface can influence mesangial function. The effect of NTS on the mesangium is due, in large part, to the glomerular injury and proteinuria which nephrotoxic antibodies produce.     

Studies on bacteriophage. II. Inhibition of lysis of Escherichia coli B by the somatic antigen of Phase II Shigella sonnei

By serological means it has been shown that E. coli B contains an antigen closely related to the protein-lipocarbohydrate complex of Phase II Sh. sonnei. Lysis of E. coli B by three of the T viruses, T₃, T₄, and T₇, can be inhibited by the Phase II dysentery antigen. It has been suggested that the receptor of E. coli B with which these viruses combine is this newly described antigenic component. Two variants of the virus T₃ have also been described, in stocks which have been treated with the Phase II antigen. One of these variants infects both Phase II Sh. sonnei and E. coli B, and the other infects only the latter microorganism; neither of the two variants is inhibited by concentrations of the Phase II antigen of 1 mg. per cc. The distinctive properties of the variants are not hereditary.