Early post-traumatic cerebral blood flow mapping: correlation with structural damage after focal injury

Focal post traumatic mass lesions such as contusions and intracerebral haematomas are common, and often difficult for neurosurgeons to manage, because little is known of their pathophysiology. We have mapped cerebral blood flow, and studied small vessel ultrastructure at different time points within the first three weeks of head injury, in patients with these lesions. A zone of ischaemic brain is always present around these lesions, and persists for weeks or months. This accords with astrocyte swelling and microvascular compression seen on electron microscopy. Focal zones of hyperaemia were also present in 42% of patients, within the first two weeks of injury, and this appeared only within apparently normal tissue as judged by late MRI or CT.

Improved detection of small cavernous hemangiomas of the liver with high-resolution three-headed SPECT

The purpose of this study was to review our experience with 99mTc-red blood cell scintigraphy for diagnosis of cavernous hemangiomas of the liver using a new three-headed, high-resolution dedicated SPECT system. Of 19 patients referred with a total of 38 lesions seen on CT, US, or MRI, 14 patients had 24 lesions that were hemangioma-positive with SPECT (all true-positives). Six of these 14 patients also had 9 hemangioma-negative lesions; all were less than or equal to 1.3 cm in size and false-negative. The remaining five patients had hemangioma-negative lesions only (1 false-negative, 4 true-negatives). Two hemangiomas were seen by SPECT that were not detected by CT, US, or MR. The sensitivity for hemangiomas greater than or equal to 1.4 cm. was 100% (20/20). The sensitivity was 33% for lesions 0.9-1.3 cm, and 20% for lesions less than or equal to 0.8 cm. The smallest hemangioma detected was 0.5 cm. These results show a definite improvement in sensitivity with high-resolution triple-headed SPECT over previously reported results using single-headed SPECT. High-resolution SPECT has improved our ability to detect small cavernous hemangiomas of the liver.

Strength training does not improve lipoprotein-lipid profiles in men at risk for CHD

Sixteen untrained males, age 46 +/- 11 yr (mean +/- SD), were studied to determine the effects of 20 wk of strength training on lipoprotein-lipid profiles and post-heparin lipase activities. All subjects had abnormal lipoprotein-lipid profiles and at least two other risk factors for coronary heart disease (CHD). To control for day-to-day variations in blood lipoprotein levels, baseline values were established by taking at least two blood samples on separate days from the training and control groups. The training program resulted in a 50% increase in upper body strength (P less than 0.001) and a 37% increase in lower body strength (P less than 0.001) as measured by the one repetition maximum test (1-RM). No changes in the 1-RM test were observed in the control group. There were no significant changes in VO2max (34.5 +/- 6.4 vs 36.2 +/- 7.4 ml.kg-1.min-1 or percent fat (25.4 +/- 4.2 vs 24.9 +/- 4.1%) with training. There were also no significant changes in plasma concentrations of triglyceride (193 +/- 96 vs 171 +/- 101 mg.dl-1), total cholesterol (231 +/- 22 vs 210 +/- 22 mg.dl-1), and HDL-C (35 +/- 6 vs 36 +/- 8 mg.dl-1), or LDL-C (139 +/- 16 vs 139 +/- 21 mg.dl-1). Furthermore, the activities of post-heparin lipoprotein lipase (9 +/- 4 vs 13 +/- 5 moles.ml-1.h-1) and hepatic lipase (35 +/- 10 vs 35 +/- 9 moles.ml-1.h-1) did not change with training.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of 99mTc-hexamethylpropyleneamine oxime cerebral blood flow mapping after acute focal ischemia in rats

Although the blood flow tracer hexamethylpropyleneamine oxime is now widely used for cerebral blood flow mapping using single-photon emission computed tomography, its uptake into acutely ischemic brain has not been well studied. We performed a double-label autoradiographic study in which 99mTc-hexamethylpropyleneamine oxime uptake was compared with [14C]iodoantipyrine-derived cerebral blood flow 0.5, 24, and 72 hours after middle cerebral artery occlusion in 11 rats. We noted excellent correspondence between iodoantipyrine and hexamethylpropyleneamine oxime autoradiograms at all times with both simultaneous tracer injection and 30-minute separation of tracer injections. When the ischemic and hyperemic areas were measured from the same brain section using the two different tracers, hexamethylpropyleneamine oxime underestimated the iodoantipyrine-derived areas by less than 1% (95% confidence interval -2.9% to 2.3%). The maximum discrepancy (-19%) was seen at high flows. When the two tracers were injected separately, the uptake of hexamethylpropyleneamine oxime was not linear compared with iodoantipyrine-derived cerebral blood flow, but the relation became linear after the Lassen correction factor was applied. Hexamethylpropyleneamine oxime uptake thus accurately represents cerebral blood flow 0.5-72 hours after acute cerebral ischemia.

Absence of both auditory evoked potentials and auditory percepts dependent on timing cues

An 11-yr-old girl had an absence of sensory components of auditory evoked potentials (brainstem, middle and long-latency) to click and tone burst stimuli that she could clearly hear. Psychoacoustic tests revealed a marked impairment of those auditory perceptions dependent on temporal cues, that is, lateralization of binaural clicks, change of binaural masked threshold with changes in signal phase, binaural beats, detection of paired monaural clicks, monaural detection of a silent gap in a sound, and monaural threshold elevation for short duration tones. In contrast, auditory functions reflecting intensity or frequency discriminations (difference limens) were only minimally impaired. Pure tone audiometry showed a moderate (50 dB) bilateral hearing loss with a disproportionate severe loss of word intelligibility. Those auditory evoked potentials that were preserved included (1) cochlear microphonics reflecting hair cell activity; (2) cortical sustained potentials reflecting processing of slowly changing signals; and (3) long-latency cognitive components (P300, processing negativity) reflecting endogenous auditory cognitive processes. Both the evoked potential and perceptual deficits are attributed to changes in temporal encoding of acoustic signals perhaps occurring at the synapse between hair cell and eighth nerve dendrites. The results from this patient are discussed in relation to previously published cases with absent auditory evoked potentials and preserved hearing.

Cerebral pharmacodynamics of physostigmine in Alzheimer's disease investigated using single-photon computerised tomography

The effects of physostigmine on patterns of rCBF in patients with pre-senile Alzheimer's disease were studied using 99mTc-labelled HMPAO SPECT. Regional CBF increased in the left cortex relative to right, with the most significant effect in left frontal and higher frontal regions. Measures of regional brain function, such as SPECT, are an important complement to psychological test batteries in understanding the effects in brain of putative antidementia drugs. SPECT brain imaging could extend our understanding of the action of psychotropic drugs in other major psychiatric illnesses.

Thyroid structure and function in bovine beta-mannosidosis

In bovine beta-mannosidosis, the thyroid in the affected newborn shows marked cytoplasmic vacuolation. There is an associated reduction in the serum concentrations of thyroxine and tri-iodothyronine.

Physiology of short-term verbal memory

These studies document a series of brain events accompanying short-term memory functions. For auditory verbal material the sequence involves at least two different sites within auditory cortex subserving sensory and cognitive processes of memorization. During the scanning of the short-term store structures within the medial temporal lobes, presumably the hippocampus, are active. There is an inconsistency between these results and the clinical observations of the need for an intact dominant parietal lobe for auditory short-term memory to function normally. Magnetic recordings showed no focal dipolar source of activity in the parietal lobe during any aspect of auditory short-term memory. The discrepancy could be accounted for by considering the parietal lobe lesion as "disconnecting" the lateral temporal cortex from the deep medial hippocampal structures thereby impeding auditory short-term functions (Geschwind, 1965). These studies show that the physiological analysis of brain events in the msec range can provide information about relatively complex cognitive processes underlying short-term memory. The magnetic and electrical recording methods provide a noninvasive way to study human brain functions involved in cognition that can then be correlated with behavioral measures of specific cognitive activities.

Virus-induced interferon alpha/beta (IFN-alpha/beta) production by T cells and by Th1 and Th2 helper T cell clones: a study of the immunoregulatory actions of IFN-gamma versus IFN-alpha/beta on functions of different T cell populations

Spleen cells, resting T cells, activated T cells, and T cell clones characterized as type 1 (Th1) and type 2 (Th2) were investigated for their ability to produce interferon (IFN) following in vitro culture with Newcastle disease virus (NDV). All of the above cell populations, including both Th1 and Th2 T cell clones, produced high levels of IFN following in vitro culture with NDV. This IFN was characterized as a mixture of IFN-alpha and IFN-beta with IFN-alpha being the predominate species of IFN contained in the mixture. IL-2 greatly enhanced the production of IFN-alpha/beta by all cell populations in response to NDV. These different T cell populations responded very differently to the immunoregulatory actions of IFN-gamma versus IFN-alpha/beta. IFN-alpha/beta was shown to be a potent inhibitor of Con A or IL-2-induced proliferation of different T cell populations. This inhibition was not associated with a reduction in lymphokine production since spleen cells or Th1 T cell clones cultured with Con A and IFN-alpha/beta had no decrease in IL-2 or IFN-gamma production when compared to Con A-stimulated control cultures. IFN-gamma had little to no inhibitory activity on Con A-induced proliferation of spleen cells. In fact, Con A-induced proliferation was usually enhanced by IFN-gamma when nylon wool-enriched T cells were assessed. Different results were observed when IFN-gamma and IFN-alpha/beta were investigated for their ability to inhibit IL-2-induced proliferation of different T helper cell clones. IFN-gamma and IFN-alpha/beta were both capable of inhibiting IL-2-induced proliferation of T cell clones characterized as type 2 (Th2). In contrast, IFN-gamma had no effect on IL-2-induced proliferation of Th1 clones. IFN-alpha/beta, however, inhibited IL-2-induced proliferative responses of both Th1 and Th2 T cell clones. These results document the facts that (1) IFN-gamma and IFN-alpha/beta differ in their immunoregulatory actions, (2) different T cell subpopulations vary in their susceptibility to IFN-gamma regulation, and (3) virus induction of IFN-alpha/beta appears to be a ubiquitous function associated with different T cell populations.

Unilateral cerebellar damage in focal epilepsy

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Tc99m HM-PAO single photon emission computed tomography in temporal lobe epilepsy

We present the results of single photon emission computed tomography (SPECT) in 40 patients with temporal lobe epilepsy and normal computed transmission tomography (CT). Abnormalities of regional cerebral blood flow were found in 26 patients. There was focal hypoperfusion alone in 14, focal hyperperfusion alone in 6, and both types of abnormality in 6. In 4 patients there were bilateral abnormalities. Repeat SPECT showed persistence of interictal hyperperfusion in 5/12 patients. There were no significant correlations between SPECT findings and clinical parameters, and no relation between the persistence of interictal hyperperfusion and time since last seizure or seizure frequency. Where SPECT and multiple surface EEG recordings were both lateralising, agreement between them was good. The results of this study support the usefulness of HMPAO SPECT in detecting lateralising abnormalities in temporal lobe epilepsy. Interictal hyperperfusion may be commoner than previous publications suggest, and may be persistent in some cases.

The time course of vasogenic oedema after focal human head injury--evidence from SPECT mapping of blood brain barrier defects

We have tomographically mapped changes in the blood brain barrier (BBB) (99 mTc Pertechnetate) in 20 patients with acute contusions, and four with acute subdural haematomas in situ. The changes were related to regional CBF, (99 mTc HMPAO SPECT) T2 weighted MRI scans, CT abnormalities and the clinical features. Seventy-five percent of contusions were accompanied by a BBB abnormality, usually a "halo" around the lesion, which was more common in scans made after the second day. All contusions demonstrated "oedema" as a zone of "T2" signal on MRI or a zone of lucency on CT, and all were accompanied by a focal zone of low CBF on SPECT. Early contusional oedema appears to be cytotoxic but in certain cases, delayed blood brain barrier lesions develop, suggesting a vasogenic component.

Measurements of regional cerebral blood flow and cognitive performance in Alzheimer's disease

Single photon emission computed tomography (SPECT) with 99mTc-HMPAO was used to image 26 patients with dementia of the Alzheimer type (DAT) and 10 healthy controls. Regional cerebral blood flow (rCBF) data indicated a relative sparing of the occipital regions in DAT. Normalisation to occipital flow illustrated highly significant CBF deficits in a number of cortical regions, particularly in the left and right posterior--temporal cortex in DAT compared to controls. The cognitive performance of DAT patients was measured using a clinical cognitive assessment procedure (CAMCOG) and numerous correlations between these scores and rCBF were obtained. The implications and value of this investigative technique are discussed.

The effects of muscle tension on cerebral circulation in blood-phobic and non-phobic subjects

This study aimed to assess whether (1) a muscle tensing procedure which has been found to be useful in the treatment of blood-phobic patients produces an increase in heart rate and cerebral blood flow and (2) whether this increase is greater than that produced by mental effort alone. Subjects were 17 volunteers with a history of fainting in response to blood-injury stimuli, (12 were phobic) and 8 volunteers with no fainting history. They were required to (a) rest, (b) do mental arithmetic, and (c) repeatedly tense and release their arm and leg muscles. It was found that Ss, heart rate and cerebral blood flow velocity were significantly greater during the muscle tensing procedure than during mental arithmetic or resting conditions. The increased cerebral blood flow produced by muscle tensing may enable blood phobic patients to prevent fainting during exposure treatment.

CT, MR and SPECT imaging in temporal lobe epilepsy

Cranial computed tomography (CT) with modified temporal lobe technique, 0.15T magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) were carried out on 30 patients with intractable temporal lobe epilepsy. Lateralising abnormalities were detected in 21/30 patients overall. Specific lesions were detected by CT in one patient and by MRI in seven patients (in one case bilateral). In addition CT detected asymmetry of the sylvian fissures or temporal horns in 10 patients, and MRI in eight patients. SPECT detected lateralising abnormalities in 19 patients (in five cases bilateral). It is concluded that low field MRI is superior to modified CT in demonstrating subtle structural lesions of the temporal lobe. Functional scanning with SPECT supports the evidence of origin of an epileptic focus in a substantial proportion of cases and may improve the selection of patients for surgery.

A double-blind randomized placebo controlled trial of thromboprophylaxis in major elective general surgery using once daily injections of a low molecular weight heparin fragment (Fragmin)

The safety and efficacy of the low molecular weight heparin fragment (Fragmin) administered as a single daily injection of 2,500 anti Xa units has been evaluated in 183 patients undergoing major elective general surgery. The study was double-blinded and placebo controlled. The active agent, or placebo, was given subcutaneously with the preoperative medication and continued postoperatively for 5-9 days. Ninety five patients received Fragmin and 88 were randomized to receive the placebo. The clinical characteristics of the two treatment groups were similar. Fragmin significantly reduced the incidence of deep venous thrombosis, as detected by a positive 125I fibrinogen leg scan, relative to the placebo treated patients (4/95, 4.2% v. 14/88, 15.9%; p = 0.008). The thrombotic events occurred predominantly (73%) amongst patients with malignancy. Haemorrhagic endpoints necessitating discontinuation of the trial treatment were 4% in each group. No severe adverse reactions or drug related deaths occurred. These results indicate that 2,500 anti Xa units of Fragmin given only once daily is effective thromboprophylaxis for patients undergoing major elective abdominal surgery.

Complete sequence of the lamprey fibrinogen alpha chain

The complete amino acid sequence of the lamprey fibrinogen alpha chain has been determined by a combination of peptide sequencing and cDNA and genomic cloning. The chain, which has an apparent molecular weight by dodecyl sulfate-polyacrylamide gel electrophoresis of ca. 100,000, is composed of 961 amino acid residues and has a calculated molecular weight of 96,722. It is distinguished by a large number of 18-residue repeats in a region where mammalian fibrinogens have 13-residue repeats. The data are in accord with our previous finding that the lamprey alpha chain has a distinctive amino acid composition, almost half the residues being glycine, serine, or threonine. The chain differs from mammalian alpha chains in that there are no cysteines in the carboxy-terminal half, and thus no intrachain loop, nor are there any RGD sequences in the lamprey alpha chain. Taken together with previous data on the sequences of the beta and gamma chains, the findings bear significantly on our understanding of fibrin formation. The alpha chain also provides an interesting case of structural convergence during evolution.

Effect of broadband noise on the human brain stem auditory evoked response

The purpose of this paper is to describe the effect of broadband continuous noise on brain stem auditory evoked responses elicited from normal-hearing and hearing-impaired individuals. The motivation for this study derives from the increasing use of noise masking paradigms in diagnostic electrophysiology, the universal presence of background noise in everyday listening environments, and the frequent observation that background noise is more detrimental to the performance of the hearing-impaired individual than to the normal-hearing individual. Four studies were designed to evaluate: (1) the sensitivity and specificity of the latency-intensity series, (2) the sensitivity and specificity of the latency-noise series, (3) the dependence of the latency-noise series on signal-to-noise ratio near electrophysiologic threshold, and (4) the dependence of the latency-noise index on the signal level at which the test is performed. The results of the studies reported herein show that the electrophysiological response to increasing masker levels is more sensitive for identifying inner ear pathology than previously used latency-intensity series measures, without compromising specificity. It is suggested that simultaneous broadband masking should be considered as a test for localization of pathology in those subjects for whom routine behavioral measurements are not possible or when the results of such measurements are equivocal.

The pattern of function-related regional cerebral blood flow investigated by single photon emission tomography with 99mTc-HMPAO in patients with presenile Alzheimer's disease and Korsakoff's psychosis

Single photon emission tomography (SPET) with the lipophilic blood flow marker 99mTc-hexamethyl propyleneamine oxime (99mTc-HMPAO) has been used to determine regional uptake of radiolabel into brain regions of patients with presenile Alzheimer's disease and Korsakoff's psychosis, and age-matched controls. Using occipital cortical uptake as reference area, the pattern of relative regional cerebral blood flow (rCBF) was determined in other cortical areas and basal ganglia. In Alzheimer's disease, reduction in rCBF occurred most strikingly in posterior temporal and parietal areas. By contrast, in Korsakoff's psychosis, posterior temporal rCBF was maintained, although there was a trend to reduced tracer uptake in other cortical areas. These impairments of flow were correlated with impairments of neuropsychological function. In Alzheimer's disease, left posterior temporal and left parietal regions in particular showed rCBF to be strongly correlated with most aspects of cognitive function. In Korsakoff's psychosis, however, impaired flow in frontal regions was correlated with impaired performance on tests of memory and orientation. The findings in Alzheimer's disease show quantitative parallels with those from studies using Positron Emission Tomography (PET), and extend our understanding of the relationship between cognition and regional brain function in dementia. The findings in Korsakoff's psychosis offer the first direct evidence linking frontal lobe dysfunction with the cognitive impairment seen in the disorder.

The use of in vitro magnetic resonance tissue studies to optimise pulse sequences in the imaging of intracranial haemorrhage

The choice of appropriate MR pulse sequences to highlight a particular pathology to best advantage is not always straightforward. In this study of intracranial haemorrhage, tissue relaxation times measured in vitro were entered into a computer program which calculated the signal intensity of each tissue (brain, blood, CSF, and bloody CSF) for all possible echo (TE) and repeat (TR) times. Analysis of graph plots of the results enabled the selection of pulse sequences which gave optimal separation of the signal intensities of intracranial haemorrhage from those of normal intracranial contents. The sequences thus chosen were used successfully in the imaging of patients with intracranial haemorrhage.