Anatomic basis of amygdaloid and hippocampal volume measurement by magnetic resonance imaging

Both the amygdala and the hippocampus are involved in the pathogenesis of a number of neurologic conditions, including temporal lobe epilepsy, postanoxic amnesia, and Alzheimer's disease. To enhance the investigation and management of patients with these disorders, we developed a protocol to measure the volumes of the amygdala and as much of the hippocampus as possible (approximately 90 to 95%) using high-resolution MRI. We present the anatomic basis of these two protocols and our results in normal control subjects. These volumetric studies of the amygdala may clarify the role of this structure in the pathogenesis of temporal lobe epilepsy.

MRI volumetric measurement of amygdala and hippocampus in temporal lobe epilepsy

We performed MRI volumetric measurements of the amygdala (AM), the hippocampal formation (HF), and the anterior temporal lobe in a group of 30 patients with intractable temporal lobe epilepsy (TLE) and in seven patients with extratemporal lobe foci. Measurements were analyzed with a semiautomated software program and the results compared with those of normal controls and correlated with the findings of all other investigations. In particular, we compared the results with the lateralization of epileptic abnormalities in the EEG. Volumetric studies of AM and HF showed lateralization of measurable atrophy consistent with that derived from extracranial and intracranial EEG examinations. The HF volumes were more sensitive and provided a lateralization in 87%. Combined measurements of AM and HF showed lateralization in 93%, always congruent with the results of EEG lateralization. This slight but important additional improvement in discrimination justifies using AM measurements in MRI volumetric studies of mesial temporal structures. Volumetric studies combined with other currently employed noninvasive techniques may diminish the need for invasive methods of investigation in patients with TLE.

A candidate reference method for determination of total protein in serum. I. Development and validation

We developed a candidate Reference Method for measuring total serum protein by use of the biuret reaction. The method involves a previously described biuret reagent (Clin. Chem. 21: 1159, 1975) and Standard Reference Material (SRM) 927 bovine albumin (National Bureau of Standards) as the standard. At 25 degrees C, color development for 30 or 60 min provides identical serum protein values. Glucose (up to 10 g/L) and bilirubin (up to 300 mg/L) do not interfere. Hemoglobin, at 3 g/L, increases apparent serum protein by 0.4 g/L. The presence of dextran in serum causes easily detected turbidity, but this interference can be eliminated by centrifuging the reaction mixture. Therapeutic concentrations of ampicillin, carbenicillin, penicillin, oxacillin, nafcillin, chloramphenicol, cephalothin, and methicillin in blood do not interfere, nor do triglycerides up to 10 g/L. Within-run and day-to-day standard deviations of the method are 0.1 and 0.4 g/L, respectively.

Hippocampal sclerosis in temporal lobe epilepsy demonstrated by magnetic resonance imaging

The value of magnetic resonance imaging in the detection of hippocampal sclerosis has been controversial. We studied 10 patients aged 22.5 +/- 6.0 years with intractable temporal lobe epilepsy selected because of a history of a prolonged childhood convulsion, which is characteristic of a group of patients in whom hippocampal sclerosis is a constant finding. All 10 patients showed reduction in size of one hippocampus associated with increased signal intensity on T2-weighted magnetic resonance images. These changes were reliably detected on coronal spin-echo images, perpendicular to the long axis of the hippocampus. Appreciation of the normal imaging anatomy of the hippocampus allowed correct interpretation of the relative changes in signal intensities of the hippocampus and adjacent temporal horn on sequential echo images. The side of the abnormal hippocampus on magnetic resonance imaging accorded with the electroencephalographic localization in all 10 patients, and with the lateralization of the early convulsions in all 6 patients where this was known. Temporal lobectomy was performed in all 10 patients. Hippocampal sclerosis was confirmed in the 3 patients in whom hippocampal tissue was available for histological examination. The value of this technique was reinforced by the excellent postoperative results, with 80% being seizure free at a mean follow-up time of 33 +/- 4 months.

An artefact in radioautography due to binding of free amino acids to tissues by fixatives

The binding of labeled free amino acids to liver and to purified protein by commonly used fixatives was investigated. Glutaraldehyde caused 25% of free leucine to be bound to serum albumin in solution, whereas formaldehyde bound only 0.5%. Liver slices were incubated for 2 min in the presence of labeled leucine and of puromycin, which permits absorption of leucine into the cell but inhibits incorporation into protein. Both counting and radioautographic techniques showed that glutaraldehyde bound 30 times, and osmic acid six times, as much free amino acid as did formaldehyde. By comparing liver slices incubated with and without puromycin for 2 min, it was calculated that in radioautographs prepared after fixation with glutaraldehyde, osmic acid, or formaldehyde 63, 25, and 4% respectively of the grains were due to binding of free amino acid. Formaldehyde, freshly prepared from paraformaldehyde, gives good preservation and is the recommended fixative for radioautography. When levels of free substrate in a tissue are high at the time fixative is added, the amount of binding of free substrate induced by the fixative should be included as a control in radioautographic experiments.

Magnetic resonance imaging in temporal lobe epilepsy: pathological correlations

A retrospective single-blind study assessing the value of magnetic resonance imaging (MRI) in 48 patients treated surgically for temporal lobe epilepsy was carried out. The imaging findings were correlated with the surgical findings in all cases. Abnormal MRI signals were detected in 34 of 48 (71%) epileptic patients and in 3 of 48 (6.2%) normal or disease control subjects. Twelve patients had structural foreign-tissue lesions, all detected by MRI. Of 14 patients with severe gliosis of the neocortex and/or mesial temporal structures, 11 had abnormal MRI scans. In patients with mild or moderate gliosis of mesial temporal structures, 6 of 12 had abnormal MRI scans. These results indicate that MRI is a sensitive technique for localizing foreign-tissue lesions, mesial temporal sclerosis, and gliosis in patients with intractable temporal lobe seizures.

Fragments of bovine serum albumin produced by limited proteolysis. Conformation and ligand binding

Twelve fragments of bovine serum albumin, isolated following limited tryptic or peptic hydrolysis, have been studied to define secondary structure and locate ligand-binding sites. Based on circular dichroism, the conformational pattern of albumin (68% alpha helix and 18% beta structure) is substantially retained by individual fragments, indicating that secondary configuration is locally determined and is not destroyed during the cleavage process nor during fragment purification. The strong bilirubin-binding site of bovine serum albumin is present in 3 of the 12 fragments. Residues 186-238 are common to the three fragments and absent from those fragments which do not bind bilirubin; consequently the strong bilirubin-binding site is suggested to involve this region. By similar reasoning, the presence of palmitate-binding sites in some fragments and not in others indicates that the three strongest sites for the binding of palmitate are located in the carboxyl-terminal two-thirds of the molecule. The first site (KA approximately 2 X 10(7) M-1) is suggested as residues 377-503; the second site (KA approximately 8 X 10(6) M-1), residues 239-306; the third site (KA approximately 2 X 10(6) M-1), residues 307-377. Bromocresol Green, a reagent used in the assay of ablumin, was bound by fragments rougly in proportion to their size but showed particular affinity for the region of the strong bilirubin-binding site. The fluorescent probe, 8-anilino-1-naphthalensulfonate, was in general bound by large fragments, supporting the concept that this ligand is held principally in clefts between domains of the macromolecule.

A multicentre, randomized, double-blind, placebo-controlled trial of naltrexone in the treatment of alcohol dependence or abuse

The opioid antagonist, naltrexone, is reported, in single centre studies, to improve the clinical outcome of individuals with alcohol dependence participating in outpatient psychosocial programmes. This is the first multicentre controlled study to evaluate the efficacy and safety of naltrexone as adjunctive treatment for alcohol dependence or abuse. Patients who met criteria for alcohol dependence (n = 169) or alcohol abuse (n = 6) were randomly assigned to receive double-blind oral naltrexone 50 mg daily (n = 90) or placebo (n = 85) for 12 weeks as an adjunct to psychosocial treatment. The primary efficacy variable was time to first episode of heavy drinking; secondary efficacy assessments included time to first drink, alcohol consumption, craving, and changes in the serum biological markers gamma-glutamyl transferase (GGT), and aspartate and alanine aminotransferases. Compliance was assessed by tablet counts and, in the naltrexone-treated group, by measurement of urinary concentrations of 6-ss-naltrexol. Forty-nine (58%) patients randomized to placebo and 53 (59%) randomized to naltrexone did not complete the study. In intention-to-treat analyses, there was no difference between groups on measures of drinking. The median reduction from baseline of serum GGT (P: < 0.05) and the reductions in alcohol craving (Obsessive and Compulsive Drinking Scale: OCDS) were greater in the naltrexone group (P: < 0.05), from approximately half-way through the study. Of 70 patients (35 placebo; 35 naltrexone) who met an a priori definition of compliance (80% tablet consumption, attendance at all follow-up appointments), those allocated to naltrexone reported consuming half the amount of alcohol (P: < 0.05), had greater median reduction in serum GGT activity (P: < 0.05), and greater reduction in alcohol craving (OCDS total score: P: < 0.05; Obsessive subscale score: P: < 0.05), compared to patients in the placebo group. Use of naltrexone raised no safety concerns. Naltrexone is effective in treating alcohol dependence/abuse in conjunction with psychosocial therapy, in patients who comply with treatment.

A prospective, randomized study comparing the results of open discectomy with those of video-assisted arthroscopic microdiscectomy

BACKGROUND

The usefulness of video-assisted arthroscopic microdiscectomy for the treatment of a herniated lumbar disc has been studied previously. In the current prospective, randomized study, the results of this procedure were compared with those of conventional open laminotomy and discectomy.

METHODS

Sixty patients who had objective evidence of a single intracanalicular herniation of a lumbar disc caudad to the first lumbar vertebra were randomized into two groups consisting of thirty patients each; Group 1 was managed with open laminotomy and discectomy, and Group 2 was managed with video-assisted arthroscopic microdiscectomy. None of the patients had had a previous operation on the low back, and all had failed to respond to nonoperative measures. Analysis of the outcomes of both procedures was based on the patient's self-evaluation before and after the operation, the preoperative and postoperative clinical findings, and the patient's ability to return to a functional status. The patients were followed for nineteen to forty-two months postoperatively.

RESULTS

On the basis of the patient's preoperative and postoperative self-evaluation, the findings on physical examination, and the patient's ability to return to work or to normal activity, twenty-eight patients (93 percent) in Group 1 and twenty-nine patients (97 percent) in Group 2 were considered to have had a satisfactory outcome. The mean duration of postoperative disability before the patients were able to return to work was considerably longer in Group 1 than in Group 2 (forty-nine compared with twenty-seven days). The patients in Group 1 used narcotics for a longer duration postoperatively. No neurovascular complications or infections were encountered in either group.

CONCLUSIONS

Although the rate of satisfactory outcomes was approximately the same in both groups, the patients who had had an arthroscopic microdiscectomy had a shorter duration of postoperative disability and used narcotics for a shorter period. These findings suggest that arthroscopic microdiscectomy may be useful for the operative treatment of specific symptoms, including radiculopathy, that are caused by lumbar disc herniation, provided that patients are properly selected--that is, they must have a herniated disc at a single level as confirmed on imaging studies, have failed to respond to nonoperative management, have no evidence of spinal stenosis, and have a herniation not exceeding one-half of the anteroposterior diameter of the spinal canal. Moreover, the surgeon must be familiar with this technique and must have received training in its use.

Atrophy of mesial structures in patients with temporal lobe epilepsy: cause or consequence of repeated seizures?

We studied 70 epileptic patients by using magnetic resonance imaging volumetric measurements of amygdala (AM) and hippocampal formation (HF). Fifty patients presented with intractable temporal lobe epilepsy (TLE), 10 patients had focal extratemporal lobe epilepsy, and 10 had generalized epilepsy. In 91% of the 45 TLE patients without foreign tissue lesions, there was significant smallness of the AM and/or HF coinciding with the side of electroencephalographic seizure onset. No significant smallness or asymmetry was demonstrated in patients with focal extratemporal or generalized epilepsy. We performed a linear regression analysis, plotting the number of years of recurrent seizures and the estimated seizure frequency against the volumes of the AM and HF. There was no correlation between either of these two parameters and AM or HF volume (p > 0.9). There was also no correlation between the patient's age and volumetric measurements of AM or HF, nor did these measurements correlate with the occurrence of generalized seizures. On the other hand, patients with antecedent prolonged febrile convulsions in early childhood had significantly smaller AM and HF, compared with those without such a history (p < 0.001). The findings indicate that repeated seizures or longer duration of epilepsy do not cause increased atrophy of AM or HF that is measurable by volumetric magnetic resonance imaging.

Dose-dependent reduction of cerebral blood flow during rapid-rate transcranial magnetic stimulation of the human sensorimotor cortex

Rapid-rate transcranial magnetic stimulation (rTMS) was used to stimulate the primary sensorimotor cortex in six healthy volunteers while regional changes in cerebral blood flow (CBF) were simultaneously measured by means of positron emission tomography. A figure-eight TMS coil (Cadwell Corticoil) was positioned, using frameless stereotaxy, over the probabilistic location of the left primary sensorimotor cortex, and a series of brief 10-Hz trains of TMS was delivered at subthreshold intensity during each of six 60-s scans. The scans differed in the number of trains delivered, namely 5, 10, 15, 20, 25, and 30 trains/scan, respectively. In the left primary sensorimotor cortex, CBF covaried significantly and negatively with the number of stimulus trains. These CBF decreases may reflect TMS-induced activation of local inhibitory mechanisms known to play a role in TMS-related phenomena, such as the electromyographic silent period.

In vitro activities of the lichen secondary metabolites vulpinic acid, (+)-usnic acid, and (-)-usnic acid against aerobic and anaerobic microorganisms

Secondary metabolites of different species of lichen were tested for their activities against a variety of microbial species. While gram-negative rods and fungi were not inhibited by these compounds, Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, and some anaerobic species (Bacteroides and Clostridium species) were susceptible at the concentrations tested. Vulpinic acid generally was less active than usnic acid, regardless of its stereochemistry. The susceptibility to usnic acid was not impaired in clinical isolates of S. aureus resistant to methicillin and/or mupirocin.

Serum albumin: recent progress in the understanding of its structure and biosynthesis

Major discoveries have been made in the past few years on the structure and mode of biosynthesis of serum albumin. The complete amino acid sequence of this protein has been determined, and its covalent structure shown to be a single peptide chain grouped into a series of nine disulfide-bonded loops. These loops appear to associate into three similar domains. By study of isolated fragments of the molecule it can be demonstrated that the binding of billirubin and the primary binding of long-chain fatty acids are functions of separate domains. The biosynthesis of albumin has been found to involve a precursor form, termed "proalbumin", in which a basic hexapeptide is attached to the amino end of the chain. Similar precursor forms are now known to have a role in the formation of other secreted proteins, but in the case of albumin the purpose of the additional peptide is not clear. Clinical methodology for albumin assay has advanced but little despite--or perhaps in part because of--the increasing use of automation. Hope for improvement is foreseen in the advent of immunochemical procedures and in a better understanding of the specificity of dye-binding reactions.

Serum and urine albumin: a progress report on their measurement and clinical significance

For about 25 years, bromcresol green and bromcresol purple have been the basis for most of the measurements of serum albumin in the US and perhaps in the world. The longevity of the methods is due to their being simple, sensitive, specific, inexpensive and relatively free from interferences. The lack of change in the serum albumin methodology is balanced by two important developments. First, the recognition of the importance of serum albumin in the maintenance of good health, and the association of decreased concentrations with increased risk of morbidity and mortality. Second, the association of albuminuria with diabetic nephropathy, which without medical intervention could lead to end-stage renal disease. The development of accurate and precise methods for urinary albumin has provided a tool to physicians to extend the length and improve the quality of life of many diabetic individuals.

Gene and cluster-specific expression of the Iroquois family members during mouse development

Mammalian homologues of the Drosophila Iroquois homeobox gene complex, involved in patterning and regionalization of differentiation, have recently been identified (Mech. Dev., 69 (1997) 169; Dev. Biol., 217 (2000) 266; Dev. Dyn., 218 (2000) 160; Mech. Dev., 91 (2000) 317; Dev. Biol., 224 (2000) 263; Genome Res., 10 (2000) 1453; Mech. Dev., 103 (2001) 193). The six members of the murine family were found to be organized in two cognate clusters of three genes each, Irx1, -2, -4 and Irx3, -5, -6, respectively (Peters et al., 2000). As a basis for further study of their regulation and function we performed a comparative analysis of the genomic organization and of the expression patterns of all six Irx genes. The genes are expressed in highly specific and regionalized patterns of ectoderm, mesoderm and endoderm derived tissues. In most tissues the pattern of expression of the clustered genes, especially of Irx1 and -2 and of Irx3 and -5, respectively, closely resembled each other while those of Irx4 and -6 were very divergent. Interestingly, the expression of cognate genes was found to be mutually exclusive in adjacent and interacting tissues of limb, heart and the laryncho-pharyncheal region. The results indicate that the Irx genes are coordinately regulated at the level of the cluster.

A Monte Carlo method for conformational analysis of saccharides

A Metropolis Monte Carlo (MMC) algorithm was applied to explore conformational spaces spanned by the exocyclic dihedral angles of four disaccharides alpha-D-Man(1-->3)-alpha-D-Man(1-->O)Me (1), alpha-D-Man(1-->2)-alpha-D-Man(1-->O)Me (2), methyl beta-cellobioside (3), and methyl beta-maltoside (4). The simulation method uses the HSEA force field and randomly samples the conformational space with an automatic preference for low-energy states. In comparison to a systematic grid search, MMC offers a much more convenient and efficient protocol for the computation of ensemble average values of experimentally accessible NMR parameters such as NOE effects or 3J coupling constants. Energy barriers of a few kcal/mol were found to be surmounted easily when running the simulations with the temperature parameter set at room temperature, whereas passing significantly higher barriers required elevated temperature parameters. Ensemble average NOE values were calculated using the MMC technique and a conventional systematic grid search showing that the MMC method adequately samples the conformational spaces of 1-4. Theoretical NOEs derived for global or local minimum conformations are different from ensemble average values, and it is shown that averaged NOEs agree significantly better with experimental data. Ensemble average NOEs for 1 derived from MMC/HSEA, and previously reported MM2CARB and AMBER calculations all showed good agreement with experimental data, with MMC/HSEA giving the closest fit.

The DTI Challenge: Toward Standardized Evaluation of Diffusion Tensor Imaging Tractography for Neurosurgery

BACKGROUND AND PURPOSE

Diffusion tensor imaging (DTI) tractography reconstruction of white matter pathways can help guide brain tumor resection. However, DTI tracts are complex mathematical objects and the validity of tractography-derived information in clinical settings has yet to be fully established. To address this issue, we initiated the DTI Challenge, an international working group of clinicians and scientists whose goal was to provide standardized evaluation of tractography methods for neurosurgery. The purpose of this empirical study was to evaluate different tractography techniques in the first DTI Challenge workshop.

METHODS

Eight international teams from leading institutions reconstructed the pyramidal tract in four neurosurgical cases presenting with a glioma near the motor cortex. Tractography methods included deterministic, probabilistic, filtered, and global approaches. Standardized evaluation of the tracts consisted in the qualitative review of the pyramidal pathways by a panel of neurosurgeons and DTI experts and the quantitative evaluation of the degree of agreement among methods.

RESULTS

The evaluation of tractography reconstructions showed a great interalgorithm variability. Although most methods found projections of the pyramidal tract from the medial portion of the motor strip, only a few algorithms could trace the lateral projections from the hand, face, and tongue area. In addition, the structure of disagreement among methods was similar across hemispheres despite the anatomical distortions caused by pathological tissues.

CONCLUSIONS

The DTI Challenge provides a benchmark for the standardized evaluation of tractography methods on neurosurgical data. This study suggests that there are still limitations to the clinical use of tractography for neurosurgical decision making.

Frameless stereotaxy for surgery of the epilepsies: preliminary experience. Technical note

Frameless stereotactic techniques used in conjunction with three-dimensional images allow accurate planning and performance of a variety of neurosurgical procedures. The authors have used the frameless stereotactic Allegro Viewing Wand system to provide real-time correlation of the operating field and computerized images in 42 neurosurgical operations, including 31 epilepsy procedures. The system consists of an image-processing computer that creates three-dimensional and triplanar images; a mobile computer to display reformatted magnetic resonance images; and a hand-guided, articulated, position-sensing arm with a probe. At the start of the operation, the probe identifies the patient's facial and scalp features and correlates these with the computerized images. The position-sensing arm can then guide the operation and locate anatomical structures and lesions of interest. This system can be used to advantage in performing smaller craniotomies and intraoperatively locating anatomical structures and lesions to be removed. Postoperative magnetic resonance images demonstrate that this technique was accurate to within 3 mm in measuring the anteroposterior resection of fixed structures, such as hippocampus and corpus callosum. Disadvantages include longer preoperative preparation for data analysis and lack of both real-time computer analysis of tissue removal and angiographic data display. Preliminary experience suggests that the viewing wand system's advantages outweigh the disadvantages, and it is most helpful as an adjunctive navigational device in the microsurgical treatment of epilepsy.

Involvement of tumor necrosis factor in endotoxin-triggered neutrophil adherence to sinusoidal endothelial cells of mouse liver and its modulation in acute phase

Tumor necrosis factor (TNF) has been shown to mediate lipopolysaccharide-induced neutrophil adhesion to liver sinusoidal endothelium in vivo. Female NMRI mice received either 5 micrograms lipopolysaccharide (R595) per animal alone (model A) or together with 116 mumol D-galactosamine (model B). One hour after injection, TNF activity in the serum was detectable to an equal extent in both models. Neutrophils in the liver, which had been identified by chloroacetate esterase staining of liver sections and quantitated by light microscopy, started to increase at 1 h and were elevated 10-fold above baseline at 6 h after application in (A) and (B). If 0.5 micrograms TNF instead of lipopolysaccharide was injected alone (model C) or together with D-galactosamine (model D), neutrophil influx into the liver was comparable to that observed in (A) or (B). Alanine aminotransferase activity in the serum was nearly normal in (A) and (C) 6 h after injection, while it reached levels up to 50-fold above baseline in models (B) and (D). This reflects the well-known D-galactosamine sensitization against lipopolysaccharide or TNF. Furthermore, degranulation of a large number of intrasinusoidal neutrophils could be observed 9 h after lipopolysaccharide-galactosamine injection. The administration of 116 mumol D-galactosamine per animal alone led neither to a measurable TNF activity in the serum nor to an increase in alanine aminotransferase activity or number of liver neutrophils. If the animals had received 50 microliter turpentine subcutaneously 24 h prior to lipopolysaccharide, TNF or D-galactosamine injection, the induced acute-phase reaction suppressed the increase of liver neutrophils in all models. Acute-phase reaction also prevented neutrophil degranulation and the rise of alanine aminotransferase in (B) to a great extent, while serum TNF activity was only minimally affected. It is concluded that TNF mediates neutrophil adhesion to the sinusoidal endothelium in vivo and that acute-phase reactants prevent lipopolysaccharide- or TNF-induced neutrophil influx into the liver.