Mucosal pseudolipomatosis of the colon

Twenty-four cases of a lesion characterized by unlined spaces in the colorectal lamina propria are presented. While lesions such as this have been reported previously as "lipomatosis" of the colon, histochemical and ultrastructural examination reveals that they are not, in fact, composed of adipocytes. It appears that they may be composed of gas trapped in the lamina propria. Because of their gross and microscopical similarity to fat, however, the term "pseudolipomatosis" is proposed.     

Clinical neurophysiology of dementia

The role of EEG in the study of the dementias is to help in the differential diagnosis of the multiple causes of this syndrome. EEG is useful in differentiating early on between treatable and as of now untreatable forms of dementia. Space-occupying lesions that give rise to dementia are reliably detected by EEG. Infectious, toxic, and metabolic processes are associated with early and severe electroencephalographic abnormalities. The "slow virus" infections show characteristic electrical patterns that reliably distinguish them from the cortical or subcortical dementias. Finally, the EEG may contribute to distinguishing between Alzheimer's disease and MID, two commonly occurring forms of dementia. The paucity of substantial early EEG abnormalities in Alzheimer's disease, although helping to differentiate it from other dementias, leaves us without a currently available physiologic test that provides positive evidence for this condition. Recent studies of EPs, however, suggest that some intermediate latency VEP components may be delayed in patients with Alzheimer's disease when compared with normal subjects. This is encouraging, as latencies in VEPs are more reliable and less variable than amplitude that has previously been reported as "abnormal" in some early Alzheimer patients. Long latency ERPs and CNV also show early abnormalities in Alzheimer's disease. Tests of eye movements such as ERPs are psychophysiologic tests requiring some degree of patient cooperation. Performance on tests of ocular smooth pursuit correlate highly with severity of the dementia syndrome in Alzheimer's disease. In contrast, smooth pursuit testing is usually normal in elderly patients with pseudodementia of depression, suggesting this test may be of some value in differentiating these two clinical disorders. Some evidence exists that smooth pursuit eye movements are also normal, at least in the early and middle stages, in Pick's disease, again suggesting that eye movement testing may prove to have some utility in differentiating this form of dementia from Alzheimer's disease. Ocular scanpaths are abnormal in dementia. They typically are poorly organized and at times perseveratory. In addition, the average durations of eye fixations during directed visual search are altered in dementia as compared with normals. The average eye fixation durations are longer with Alzheimer's disease and briefer in patients with frontal lobe tumors as compared with elderly normal controls. These group differences suggest differing scanning strategies for these two forms of dementia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Tensile properties of fresh human calcaneal (Achilles) tendons

The purpose of this study was to measure the tensile properties of fresh human calcaneal (Achilles) tendons. Twenty fresh cadaveric (age range = 57-93 years) bone-Achilles tendon complexes were harvested within 24 hr postmortem. The calcaneus together with 15 cm of the Achilles tendon extending proximally from the insertion on the calcaneus was clamped and biomechanically tested. Each tendon was firmly fixed in clamps in an MTS Systems Corporation MTS testing machine and tension was applied at a displacement rate of 8 cm per minute until the tendon failed. The tensile force and tensile strain (as measured using an extensometer) were recorded and plotted using onboard software. The narrow age range of our donors prevented any meaningful correlation between age and tensile properties; however, the results showed that: 1) the average ultimate tensile strength (UTS) of the human Achilles tendon was 1189 N (range = 360-1,965), 2) there was a correlation between left and right legs for UTS, 3) there was a correlation between left and right legs in regard to cross sectional area, and 4) there was no correlation between UTS and cross-sectional area.     

Effects of [3H]-BIDN,a novel bicyclic dinitrile radioligand for GABA-gated chloride channels of insects and vertebrates

1. The radiolabelled bicyclic dinitrile, [³H]-3,3-bis-trifluoromethyl-bicyclo[2.2.1]heptane-2,2-dicarbonitrile ([³H]-BIDN), exhibited, specific binding of high affinity to membranes of the southern corn rootworm (Diabrotica undecimpunctata howardi) and other insects. A variety of γ-aminobutyric acid (GABA) receptor convulsants, including the insecticides heptachlor (IC₅₀, 35±3 nM) and dieldrin (IC₅₀, 93±7 nM), displaced [³H]-BIDN from rootworm membranes. When tested at 100 μM, 1-(4-ethynylphenyl)-4-n-propyl-2,6,7-trioxabicyclo[2.2.2]octane(EBOB), 4-t-butyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-1-thione (TBPS), 1-phenyl-4-t-butyl-2,6,7-trioxabicyclo[2.2.2]octane (TBOB) and picrotoxin failed to displace 50% of [³H]-BIDN binding to rootworm membranes indicating that the bicyclic dinitrile radioligand probes a site distinct from those identified by other convulsant radioligands.
2. Dissociation studies showed that dieldrin, ketoendrin, toxaphene, heptachlor epoxide and α and β endosulphan displace bound [³H]-BIDN from rootworm membranes by a competitive mechanism.
3. Rat brain membranes were also shown to possess a population of saturable, specific [³H]-BIDN binding sites, though of lower affinity than in rootworm and with a different pharmacological profile. Of the insecticidal GABAergic convulsants that displaced [³H]-BIDN from rootworm, cockroach (Periplaneta americana) and rat brain membranes, many were more effective in rootworm.
4. Functional GABA-gated chloride channels of rootworm nervous system and of cockroach nerve and muscle were blocked by BIDN, whereas cockroach neuronal GABA_B receptors were unaffected.
5. Expression in Xenopus oocytes of either rat brain mRNA, or cDNA-derived RNA encoding a GABA receptor subunit (Rdl) that is expressed widely in the nervous system of Drosophila melanogaster resulted in functional, homo-oligomeric GABA receptors that were blocked by BIDN. Thus, BIDN probes a novel site on GABA-gated Cl⁻ channels to which a number of insecticidally-active molecules bind.

     

Symptomatic pulmonary complications from liquid acrylate embolization of brain arteriovenous malformations.

PURPOSETo describe symptomatic pulmonary emboli from brain arteriovenous malformation embolization with liquid acrylates and to analyze the reasons for these complications and describe preventive techniques.METHODSThe clinical records of 182 patients embolized with acrylate glue since 1978 for treatment of brain AVMs were searched for evidence of symptomatic pulmonary complications. Originally iso-butyl-2-cyanoacrylate and more recently n-butyl-2-cyanoacrylate were used in all patients. Arteriovenous malformation morphology, amounts and techniques of glue injection, and clinical and radiologic investigations in the symptomatic patients were recorded.RESULTSThree patients had pulmonary symptoms within 48 hours of glue injection. One patient with a left frontal arteriovenous malformation had embolization with an isobutyl-2-cyanoacrylate/pantopaque/acetic acid mixture; severe pleuritic chest pain developed 2 days later. One patient with a left temporal and one with a left cerebellar arteriovenous malformation had embolization with n-butyl-2-cyanoacrylate/lipiodol mixtures; a cough, pleuritic chest pain, and bloody sputum developed in both within 24 hours. Two patients experienced a significant drop in PO2. No flow-arrest techniques were used for any of the injections in these three patients. All patients demonstrated significant changes on chest x-ray and CT chest examinations. All were treated conservatively and recovered spontaneously.CONCLUSIONSSymptomatic pulmonary complications can occur after acrylate glue injection, particularly when delivery systems without flow arrest are used in high-flow vascular brain lesions. Techniques using acetic acid to delay polymerization time and "sandwich" techniques in which glue is pushed with dextrose are also more susceptible to this complication.     

Accelerated EM reconstruction in total-body PET: potential for improving tumour detectability

Total-body positron emission tomography (PET) is a useful diagnostic tool for evaluating malignant disease. However, tumour detection is limited by image artefacts due to the lack of attenuation correction and noise. Attenuation correction may be possible using transmission data acquired after or simultaneously with emission data. Despite the elimination of attenuation artefacts, however, tumour detection is still hampered by noise, which is amplified during image reconstruction by filtered backprojection (FBP). We have investigated, as an alternative to FBP, an accelerated expectation maximization (EM) algorithm for its potential to improve tumour detectability in total-body PET. Signal to noise ratio (SNR), calculated for a tumour with respect to the surrounding background, is used as a figure of merit. A software tumour phantom, with conditions typical of those encountered in a total-body PET study using simultaneous acquisition, is used to optimize and compare various reconstruction approaches. Accelerated EM reconstruction followed by two-dimensional filtering is shown to yield significantly higher SNR than FBP for a range of tumour sizes, concentrations and counting statistics (deltaSNR = 6.3 +/- 3.9, p < 0.001). The methods developed are illustrated by examples derived from physical phantom and patient data.     

Whole body protein turnover in children with human immunodeficiency virus (HIV) infection

The purpose of this study was to determine the rate of whole body protein turnover (WBPT) in human immunodeficiency virus (HIV)-infected children, and to determine the relationship between WBPT and growth. The rate of WBPT was calculated from the cumulative excretion of labeled urinary ammonia after a single intravenous dose of 15N-glycine in three groups of children: 1) HIV+ with growth retardation (HIV+ Gr); 2) HIV+ with normal growth (HIV+); and 3) HIV-uninfected with normal growth (HIV-). Twenty-six children between 2 and 11 y of age were studied (10 HIV+ Gr, 12 HIV+, 4 HIV-). All children were afebrile and free of acute infection during the study. Rates of WBPT (mean +/- SD) for the study groups were: HIV+ Gr, 12.2 +/- 4.8; HIV+, 10.7 +/- 5.1; and HIV-, 8.6 +/- 2.1 g.protein.kg-1.d-1 (NS, P > 0.05). Although not statistically significant, mean WBPT was 42% greater in HIV+ Gr, and 24% greater in HIV+ compared to HIV-. Statistically significant correlations were found between WBPT and Z scores for height (r = -0.39, P = 0.05) and weight-for-age (r = -0.51, P = 0.01) and dietary intake of protein (r = 0.39, P = 0.05), and between protein balance (synthesis-catabolism) and intakes of energy (r = 0.47, P = 0.02) and protein (r = 0.40, P = 0.04). There was no statistically significant correlation between WBPT and resting energy expenditure (r = 0.27, P = 0.19), or CD4 cell number (r = 0.05, P = 0.82). These data suggest an association between increased rates of protein turnover and low weight and height-for-age Z scores, and that it may be possible to achieve positive protein balance given an adequate intake of nutrients.