Regional differences in the reduction in cerebral FDG uptake induced by the ketogenic diet

BACKGROUND

The postulated benefits of the ketogenic diet in the management of multiple medical conditions have seen more patients who are in therapeutic ketosis attending 18F-FDG PET scans. This study aimed to investigate the effect of ketosis on cerebral glucose metabolism in a clinical PET scanning environment using 18F-FDG uptake as a surrogate marker.

METHODS

A retrospective audit was conducted of the brain 18F-FDG uptake in 52 patients who underwent PET scans for possible cardiac sarcoidosis or suspected intracardiac infection, following a ketogenic diet and prolonged fasting. SUVbw for whole brain and separate brain regions was compared with serum glucose and serum ketone body (beta-hydroxybutyrate) levels.

RESULTS

The expected negative association between serum glucose levels and whole brain 18F-FDG uptake was confirmed. A reduction in SUVbw due to increasing serum ketones levels was also observed that was independent of and in addition to the effects of glucose. The magnitude of the reduction in SUVbw related to serum glucose level and serum ketone level was found to be greater in the precuneus than in the cerebellum or whole brain.

CONCLUSION

In a real-world clinical PET setting, cerebral 18F-FDG uptake appears to be affected by glycaemia and ketonaemia. This means when assessing the brain, both serum glucose and ketone levels need to be considered when SUVs are used to distinguish between pathologic and physiologic states. The magnitude of this effect appears to vary between different brain regions. This regional difference should be taken into consideration when selecting the appropriate brain region for SUV normalisation, particularly when undertaking database comparison in the assessment of dementia.

The vector ecology of introduced Culex quinquefasciatus populations, and implications for future risk of West Nile virus emergence in the Galápagos archipelago

Culex quinquefasciatus Say (Diptera: Culicidae), an important vector of West Nile virus (WNV) in the U.S.A., was first detected on the Galápagos Islands (Ecuador) in the 1980s. However, little is known of its ecology, distribution or capacity for arbovirus transmission in the Galápagos. We characterize details of lifecycle (including gonotrophic period), temporal abundance, spatial distribution, vector competence and host-feeding behaviour. Culex quinquefasciatus was detected on five islands of the Galápagos during 2006-2011. A period of 7-14 days was required for egg-adult emergence; water salinity above 5 ppt was demonstrated to hinder larval development. Blood-meal analysis indicated feeding on reptiles, birds and mammals. Assessment of WNV vector competency of Galápagos C. quinquefasciatus showed a median infectious dose of 7.41 log₁₀ plaque-forming units per millilitre and evidence of vertical transmission (minimal filial infection rate of 3.7 per 1000 progeny). The distribution of C. quinquefasciatus across the archipelago could be limited by salt intolerance, and its abundance constrained by high temperatures. Feeding behaviour indicates potential to act as a bridge vector for transmission of pathogens across multiple taxa. Vertical transmission is a potential persistence mechanism for WNV on Galápagos. Together, our results can be used for epidemiological assessments of WNV and target vector control, should this pathogen reach the Galápagos Islands.

Genetic diversity, population structure and drug resistance of Mycobacterium tuberculosis in Peru

This paper presents the first evaluation of the molecular epidemiology of Mycobacterium tuberculosis in Peru. We characterised 323 isolates using spoligotyping and mycobacterial interspersed repetitive units variable number tandem repeats (MIRU-VNTR) typing. We aimed to determine the levels of genetic diversity and genetic differentiation among and within Peruvian isolates and the epidemiological factors which may be driving patterns of population structure and evolution of M. tuberculosis in Peru. Our results compared to the fourth international spoligotyping database (SpolDB4) and MIRU-VNTRplus, show that the main M. tuberculosis families present are Latin American-Mediterranean, Haarlem, T, and Beijing. Bayesian clustering recovered 15 groups in the Peruvian M. tuberculosis isolates, among which two were composed mainly of orphans, implying the presence of native "Peruvian" strains not previously reported. Variable levels of association with drug resistance were observed, with Beijing genotypes not showing any association with multidrug resistance, while in other groups MIRU-VNTR loci 2, 23, 31, and 40 were found to be associated with the multidrug-resistant tuberculosis (MDR-TB) phenotype, suggesting that a linkage disequibrium between these MIRU and drug resistance loci may be present. Genetic differentiation was present among drug resistant and sensitive strains. Ethambutol appeared to be the main driver of differentiation, suggesting that strong selection pressure could have been exerted by drug treatment in Peru over recent years.

Fossil-calibrated molecular phylogenies reveal that leaf-mining moths radiated millions of years after their host plants

Coevolution has been hypothesized as the main driving force for the remarkable diversity of insect-plant associations. Dating of insect and plant phylogenies allows us to test coevolutionary hypotheses and distinguish between the contemporaneous radiation of interacting lineages vs. insect 'host tracking' of previously diversified plants. Here, we used nuclear DNA to reconstruct a molecular phylogeny for 100 species of Phyllonorycter leaf-mining moths and 36 outgroup taxa. Ages for nodes in the moth phylogeny were estimated using a combination of a penalized likelihood method and a Bayesian approach, which takes into account phylogenetic uncertainty. To convert the relative ages of the moths into dates, we used an absolute calibration point from the fossil record. The age estimates of (a selection of) moth clades were then compared with fossil-based age estimates of their host plants. Our results show that the principal radiation of Phyllonorycter leaf-mining moths occurred well after the main radiation of their host plants and may represent the dominant associational mode in the fossil record.

Selection and recombination drive the evolution of MHC class II DRB diversity in ungulates

Major histocompatibility complex (MHC) antigen-presenting genes are the most variable loci in vertebrate genomes. Host-parasite co-evolution is assumed to maintain the excessive polymorphism in the MHC loci. However, the molecular mechanisms underlying the striking diversity in the MHC remain contentious. The extent to which recombination contributes to the diversity at MHC loci in natural populations is still controversial, and there have been only few comparative studies that make quantitative estimates of recombination rates. In this study, we performed a comparative analysis for 15 different ungulates species to estimate the population recombination rate, and to quantify levels of selection. As expected for all species, we observed signatures of strong positive selection, and identified individual residues experiencing selection that were congruent with those constituting the peptide-binding region of the human DRB gene. However, in addition for each species, we also observed recombination rates that were significantly different from zero on the basis of likelihood-permutation tests, and in other non-quantitative analyses. Patterns of synonymous and non-synonymous sequence diversity were consistent with differing demographic histories between species, but recent simulation studies by other authors suggest inference of selection and recombination is likely to be robust to such deviations from standard models. If high rates of recombination are common in MHC genes of other taxa, re-evaluation of many inference-based phylogenetic analyses of MHC loci, such as estimates of the divergence time of alleles and trans-specific polymorphism, may be required.

Resonant coupling between bulk waves and guided modes in a dielectric slab with a thick holographic grating

What we believe to be a new type of resonant coupling of an incident bulk wave into guided modes of a slab with a thick holographic grating is shown to occur in the presence of strong frequency detunings of the Bragg condition. This happens through the reflection of the strongly noneigen +1 diffracted order with the slab-grating boundaries, the resultant reflected waves forming a guided slab mode. Rigorous coupled-wave analysis is used for the numerical analysis of the predicted resonant effects. Possible applications include enhanced options for the design of multiplexing and demultiplexing systems, optical signal-processing devices, optical sensors, and measurement techniques.

Bottlenecks, drift and differentiation: the population structure and demographic history of sika deer (Cervus nippon) in the Japanese archipelago

We assessed genetic differentiation and diversity in 14 populations of sika deer (Cervus nippon) from Japan and four populations of sika deer introduced to the UK, using nine microsatellite loci. We observed extreme levels of differentiation and significant differences in diversity between populations. Our results do not support morphological subspecies designations, but are consistent with previous mitochondrial DNA analyses which suggest the existence of two genetically distinct lineages of sika deer in Japan. The source of sika introduced to the UK was identified as Kyushu. The underlying structure of Japanese populations probably derives from drift in separate glacial refugia and male dispersal limited by distance. This structure has been perturbed by bottlenecks and habitat fragmentation, resulting from human activity from the mid-nineteenth century. Most current genetic differentiation and differences in diversity among populations probably result from recent drift. Coalescent model analysis suggests sika on each of the main Japanese islands have experienced different recent population histories. Hokkaido, which has large areas of continuous habitat, has maintained high levels of gene flow. In Honshu the population is highly fragmented and is likely to have been evolving by drift alone. In Kyushu there has been a balance between gene flow and drift but all the populations have experienced high levels of drift. Habitat fragment size was not significantly associated with genetic diversity in populations but there was a significant correlation between habitat fragment size and effective population size.

Introgression through rare hybridization: A genetic study of a hybrid zone between red and sika deer (genus Cervus) in Argyll, Scotland

In this article we describe the structure of a hybrid zone in Argyll, Scotland, between native red deer (Cervus elaphus) and introduced Japanese sika deer (Cervus nippon), on the basis of a genetic analysis using 11 microsatellite markers and mitochondrial DNA. In contrast to the findings of a previous study of the same population, we conclude that the deer fall into two distinct genetic classes, corresponding to either a sika-like or red-like phenotype. Introgression is rare at any one locus, but where the taxa overlap up to 40% of deer carry apparently introgressed alleles. While most putative hybrids are heterozygous at only one locus, there are rare multiple heterozygotes, reflecting significant linkage disequilibrium within both sika- and red-like populations. The rate of backcrossing into the sika population is estimated as H = 0.002 per generation and into red, H = 0.001 per generation. On the basis of historical evidence that red deer entered Kintyre only recently, a diffusion model evaluated by maximum likelihood shows that sika have increased at approximately 9.2% yr-1 from low frequency and disperse at a rate of approximately 3.7 km yr-1. Introgression into the red-like population is greater in the south, while introgression into sika varies little along the transect. For both sika- and red-like populations, the degree of introgression is 30-40% of that predicted from the rates of current hybridization inferred from linkage disequilibria; however, in neither case is this statistically significant evidence for selection against introgression.

Bovine microsatellite loci are highly conserved in red deer (Cervus elaphus), sika deer (Cervus nippon) and Soay sheep (Ovis aries)

We tested 174 bovine microsatellite primer pairs for use in a primitive breed of sheep and two species of deer. Of 173 markers, 127 (73.4%) gave a product in Soay sheep (Ovis aries) of which 54 (42.5%) were polymorphic. One hundred and twenty-nine of 174 (74.1%) markers gave a product in red deer (Cervus elaphus) of which 72 (55.8%) were polymorphic. In sika deer (Cervus nippon) 126 of 171 (73.7%) microsatellite primers gave a product with 47 (37.3%) polymorphic. The proportion of bovine microsatellite loci conserved across artiodactyl species was significantly greater in this study than previously reported. Reasons for this high degree of microsatellite conservation are discussed. We suggest that a high resolution comparative map of the artiodactyls can be constructed using microsatellites.

Patterns of extensive genetic differentiation and variation among European harbor seals (Phoca vitulina vitulina) revealed using microsatellite DNA polymorphisms

The harbor seal (Phoca vitulina) has the most extensive distribution of any phocid seal species. An analysis of population structure in this species across its European range was made using 7 phocid derived microsatellites in a sample of 1,029 individuals from 12 separate geographic areas. Despite the species potential for long-distance movement, significant genetic differentiation between areas was observed using an unbiased estimator of RST. Six distinct population units were identified: Ireland-Scotland, English east coast, Waddensea, western Scandinavia (Norway-Kattegat-Skagerrak-west Baltic), east Baltic, and Iceland. Little local substructuring is present along coastlines with a continuous distribution of breeding animals, but differentiation does increase with geographic distance. The degree of differentiation is greater over equivalent distances where the distribution is discontinuous, such as along coasts where breeding colonies are separated by large distances or by stretches of open sea. Patterns of population differentiation derived from microsatellites are very similar to those obtained from previous mitochondrial DNA analysis and suggest that philopatry in harbor seals operates over 300-500 km. In Europe, harbor seals have experienced a complex demographic history and patterns of population structure are likely to have been affected by natural environmental influences such as Pleistocene glaciations and epizootics. Comparison of Nm values from an unbiased estimator of RST, GST, and theta are consistent and, in some cases, may indicate populations where conditions deviate from the expectations of the RST model.

Chronic pain in a victim of attempted homicide

This Medical Psychology Forum focuses on the problem of chronic pain in a patient with a neurologic deficit incurred when he became the victim of an attempted homicide. Murderous anger, wishes for revenge and intolerance of helplessness and passivity proved closely intertwined with the patient's awareness of pain and his capacity to bear it. The use of a dorsal column stimulator to “mask” the pain and the role of personality factors in his adjustment to disability are discussed.

Triple-helical DNA as a reversible block of the branch point in a partially symmetrical DNA four-arm junction

DNA branch migration is a fundamental process in genetic recombination. A new model system has been developed for studying branch migration in a small synthetic four-arm junction. A mathematical method for describing branch-point movement by discrete steps in such junctions is also presented. The key to our experimental system is the ability to fix the location of the branch point during the assembly of the junction with a reversible block. The block is provided by a short oligonucleotide that forms triplex DNA adjacent to the initial location branch point at low pH. Raising the pH causes the triplex strand to dissociate, making the branch point free to migrate. Once mobile, the branch point can run off the end of the junction. The time-course for this runoff is consistent with a random walk of the branch point. If it is assumed that one migration step moves the branch point one base-pair, the time-course gives a rate constant for one step of 1.4 second-1 at 37 degrees C in 10 mM MgCl2, 50 mM NaCl. These values are consistent with other measurements of non-enzymatic branch migration. We have also monitored the spread of the branch points directly with T4 endonuclease VII. Using EcoRI restriction endonuclease, we have shown that the binding of this protein to the arms of the junction essentially blocks branch migration through the binding site. In these experiments Ca2+ replaces Mg2+, and the enzyme does not cleave the DNA. In vivo there must be a special process to get branch points to migrate past bound proteins.

Interspecific microsatellite markers for the study of pinniped populations

Microsatellites have rapidly become the marker of choice for a wide variety of population genetic studies. Here we describe 20 pinniped microsatellite markers which have been tested across 18 pinniped species. The majority of these markers have broad utility in all pinnipeds and provide a strong base for detailed population genetic studies in the Pinnipedia.

Head position signals used by parietal neurons to encode locations of visual stimuli

The mechanism for object location in the environment, and the perception of the external world as stable when eyes, head and body are moved, have long been thought to be centred on the posterior parietal cortex. However, head position signals, and their integration with visual and eye position signals to form a representation of space referenced to the body, have never been examined in any area of the cortex. Here we show that the visual and saccadic activities of parietal neurons are strongly affected by head position. The eye and head position effects are equivalent for individual neurons, indicating that the modulation is a function of gaze direction, regardless of whether the eyes or head are used to direct gaze. These data are consistent with the idea that the posterior parietal cortex contains a distributed representation of space in body-centred coordinates.

Discovery of Intense Gamma-Ray Flashes of Atmospheric Origin

Detectors aboard the Compton Gamma Ray Observatory have observed an unexplained terrestrial phenomenon: brief, intense flashes of gamma rays. These flashes must originate in the atmosphere at altitudes above at least 30 kilometers in order to escape atmospheric absorption and reach the orbiting detectors. At least a dozen such events have been detected over the past 2 years. The photon spectra from the events are very hard (peaking in the high-energy portion of the spectrum) and are consistent with bremsstrahlung emission from energetic (million-electron volt) electrons. The most likely origin of these high-energy electrons, although speculative at this time, is a rare type of high-altitude electrical discharge above thunderstorm regions.

Postoperative utilization of critical care services by cardiac surgery: a multicenter study in the Canadian healthcare system

OBJECTIVES

To describe patterns of critical care services used after cardiac surgery and to evaluate whether variations in the process of care influence outcome.

DESIGN

Multicenter, prospective study.

SETTING

A convenience sample of four cardiac surgical units: three in university-affiliated (teaching) hospitals and one in a nonteaching regional referral center.

PATIENTS

A "consecutive sample" of 335 patients after cardiac surgery in four hospitals.

INTERVENTIONS

Data were collected regarding all cardiac surgery patients admitted to the critical care units in the four test hospitals.

MEASUREMENTS AND MAIN RESULTS

The critical care unit and hospital lengths of stay and survival were followed. The Therapeutic Intervention Scoring System (TISS) was used to assess the intensive care unit (ICU) interventions used during the first 24 hrs in the ICU and for the final 24 hrs before discharge from the ICU. The severity of illness on admission was assessed using the Acute Physiology and Chronic Health Evaluation (APACHE) scoring system. For patients having similar procedures (e.g., aortocoronary bypass and nonaortocoronary bypass procedures) and with similar outcome (mortality/total hospital length of stay), we found significant differences in the pattern of ICU resource utilization among hospitals. Significant (p < .05) differences in unit length of stay were related to varying factors in different hospitals. In hospital unit A, the type of procedure and preoperative chronic health status influenced unit length of stay (aortocoronary bypass 2.8 +/- 1.7 days; nonaortocoronary bypass 8.7 +/- 8.9 days) because length of stay was different for differing procedure groups. In hospital unit B, the critical care management system and lack of step-down (intermediate care) unit availability resulted in an increased unit length of stay for aortocoronary bypass patients (5.1 +/- 4.5 days) as compared with the other units (mean ICU lengths of stay of 2.8, 2.3, and 3.0 days, respectively). Unit B kept patients for monitoring purposes and had a reduced need for critical care nursing on the day of discharge (TISS = 7.5 +/- 5.5) as compared with the other units (mean TISS scores of 27.4, 23.2, and 21.5).

CONCLUSIONS

Significant differences exist among hospitals in the same healthcare system in the utilization of critical care services for cardiac surgery. In spite of these differences, for similar patient "input," the outcome (mortality and hospital lengths of stay) appeared similar. Assessments of utilization of critical care must focus on more detailed specific issues than unit length of stay, and must include factors such as availability of intermediate care areas, the unit management system, chronic health status, and the operative procedures performed, if a utilization management process is to effect improved resource use in critical care.

Social support networks of adults with mental retardation who live at home

The social support networks of 418 adults with mental retardation who live at home were found to be large, durable, active, and diverse in their composition. Family members predominated as members of these support networks. Differences were found in many network characteristics based on the gender and level of mental retardation of the adults. Males and those with the most severe mental retardation were found to be at risk for social isolation. Contrasts with the social support networks of adults in nonfamily settings were discussed.

Is outcome worse in a small volume Canadian trauma centre?

The minimum number of seriously injured patients required to maintain clinical competence and achieve acceptable clinical competence in a single trauma centre is unknown. It has been suggested that the probability of survival is improved in hospitals treating greater than 200 trauma patients annually. We sought to determine if probability of survival was lower in our small volume centre. Between 1986 and 1989, 752 (522 male, 230 female; average age, 36 years) trauma patients were admitted to our institution. The major mechanism of injury was blunt (89%). All patients underwent trauma severity scoring. Trauma Score, Injury Severity Score, and a Revised Trauma Score were used to derived the probability of survival by the TRISS method. The mean Injury Severity Score was 23.3 and the mean Trauma Score was 13.2. The overall mortality rate was 15.8%. The Z statistic demonstrated no significant difference between actual and predicted deaths for the 4-year period or for any individual year (range, -1.05 to 1.26, p greater than 0.05). The M statistic was 0.753. We conclude that, despite fewer trauma patient admissions (less than 200 per year), comparable clinical results can be achieved by surgeons dedicated to trauma management.

Elevation of pain threshold to tooth shock by brain stimulation in primates

Electrical stimulation of the brain (ESB) for modulation of pain has been previously demonstrated in primates, but many of the sites which yield stimulation-produced analgesia (SPA) also elicit aversive side effects. In order to examine the aversive as well as analgesic effects of brain stimulation, nine rhesus monkeys (Macaca mulatta) were first trained to press a lever to escape or titrate noxious tooth shock. Stimulating electrodes were placed under the frontal cortex in 4 monkeys and were implanted in the diencephalon, brain stem, and cerebellum of five remaining monkeys. Diencephalic stimulation sites resulted in marked elevations of tooth shock threshold at ESB intensities which did not elicit aversive behaviors. The analgesic effects lasted up to 2 h past ESB offset. Moderate elevations of tooth shock threshold were also observed with orbital cortex stimulation. The midbrain central gray and the nucleus raphe magnus, however, did not greatly alter tooth shock level and typically resulted in aversive reactions. The diencephalic sites which elicited SPA also led to self-stimulation behavior, whereas stimulation of the brain stem or cerebellum usually resulted in escape responses. These findings thus indicate that, in primates, more effective relief of pain can be achieved with electrical activation of the medial diencephalon than with brain stem stimulation.

Dorsal spinal cord stimulation in the treatment of multiple sclerosis

Previously published work indicated significant improvement in the symptoms of multiple sclerosis with dorsal spinal cord stimulation. In this study 23 patients with multiple sclerosis documented by history, examination, laboratory studies, and clinical course were treated with dorsal spinal cord stimulation and followed for 19 to 45 months (mean, 32 months). Pre- and postoperative clinical assessment was carried out using the Kurtzke Scale. Walking velocity, upper limb coordination, sphincter function, and sensory function were also evaluated quantitatively. No statistically significant objective improvement in any of these measures was demonstrated. Fifty per cent of the patients initially reported subjective symptomatic improvement, but this declined to 30% at last follow-up. Fifteen of 23 patients experienced complications related mainly to the hardware used and required a total of 21 subsequent operative procedures for correction of these complications. These results do not support the continued clinical use of dorsal spinal cord stimulation in the symptomatic treatment of multiple sclerosis.

Release of antidiuretic hormone during mass-induced elevation of intracranial pressure

There are complex osmotic and non-osmotic factors regulating release of antidiuretic hormone (ADH). A wide variety of intracranial pathological processes may trigger ADH release sufficient to produce clinically recognizable hyponatremia, or the "inappropriate ADH syndrome." We systematically studied one non-osmotic trigger, namely mass-induced elevated intracranial pressure (ICP). Initial experiments established baseline data in normal rhesus monkeys: anesthetized animals displayed appropriate rises and falls in immunoreactive urinary ADH in response to intravenously administered hypertonic and hypotonic infusions. Next, ballon catherters were implanted subdurally over temporal lobes and the animals were allowed to recover. The final experiment consisted of anethetizing the animals, monitoring arterial blood pressure and blood gases, and retrieving timed urinary specimens while continuously recording ICP during infusion-pump expansion of the subdural ballon. A nonlethal and a lethal series of ballon-expansion experiments were done. Control values of urinary ADH were 783 +/- 125 muU/15 min, and ICP was less than 10 mm Hg. During nonlethal mass expansion ADH output rose of 3433 +/- 269 millimicronU/15 min while ICP averaged 65 mm Hg (measured at completion of mass expansion). While the mass was maintained, hypotonic infusion produced unchanged urinary ADH output of 3452 +/- 277 muU/15 min. During lethal experiments, urinary ADH rose still higher to 4339 +/- 1887 muU/15 min associated with ICP averaging 100 mm Hg. We concluded that there is a direct relationship between the magnitude of ICP and the amount of ADH release, and that during elevated ICP the ADH release is not suppressed by hypotonic infusion.

The craniotubular bone modeling disorders: a neurosurgical introduction to rare skeletal dysplasias with cranial nerve compression

The craniotubular bone modeling disorders are a group of skeletal dysplasias which involve predominantly the skull and long bones. The cranial involvement includes both external facial deformities and internal bony overgrowth about the cranial foramina and fissures. The latter commonly leads to cranial nerve compression, particularly of the optic nerve. Craniotomy and cranial nerve decompression can give substantial benefit to selected patients with these diseases but the severe bony abnormalities create technical problems which prevent surgery in some extreme cases. These disorders are genetically determined but the basic pathophysiologic mechanism has been delineated for only a few types and non-surgical treatment remains supportive.

Neurologic complications of gas myelography by the lumbar route

Gas myelography is not a new technique, but its acceptance in neuroradiologic diagnosis has been relatively recent. Previously reported series have emphasized the benign nature of this technique and the lack of significant accompanying complications. From a series of 174 gas myelograms performed during a four-year period, two reports are presented wherein transient exacerbation of neurologic deficit followed exchange of cerebrospinal fluid and gas under pressure by the lumbar route. One patient with cervical spondylotic myelopathy experienced an increase in paresis, while another was found to have marked fasciculations. Speculation regarding possible mechanisms involved with these complications is presented. It is suggested that exchange of cerebrospinal fluid and gas under pressure via the lumbar route be used with caution in those patients with compromised cervical spinal cords.

Validity of the 24-hr. recall. Analysis of data obtained from elderly subjects

Tests of the validity of the 24-hr. dietary recall were done by comparing actual with recalled intakes for eight nutrients and the MAR (mean adequacy ratio) for a sample of seventy-six subjects age sixty years or older. Validity was tested by using paired-t tests and regression analysis. In the paired-t test, no significant difference was found between the mean recalled and the mean actual intake of nutrients, with the exception of calories. Using regression analysis, results indicated that for three of the eight nutrients considered (calories, protein, and vitamin A), small intakes tend to be over-reported and large intakes under-reported (p less than .05). Thus, for these three nutrients, the recall seems to be statistically conservative for group comparisons; it would seldom, if ever, indicate a difference in intake where no difference exists. But, it could yield a false negative, i.e., an indication of no significant difference, when, in fact, a difference does exist. Clearly, more research is needed, both to replicate this study and to develop techniques with greater internal validity for comparing the dietary intakes of groups.

Large optic nerve glioma with normal vision

When the diagnosis of optic glioma is made, the visual loss is most often mildly or profoundly impaired. We report the details of the unusual situation where central visual acuity, visual fields, and color vision were normal at the time a large optic nerve glioma was demonstrated in a young boy. To our knowledge, this is the first case report containing ophthalmologic, neuroradiologic, surgical, and histologic details illustrating the rare association of normal vision and an optic glioma.

Treatment of vertebrojugular fistula by balloon occlusion. Case report

✓ The authors report the successful treatment of a posttraumatic vertebrojugular fistula by a combination of vascular trapping and intraluminal balloon occlusion.

Cervical spine injuries in infants. Problems in management

The authors point out the unique anatomical and therapeutic considerations involved in injuries of the cervical spine and cord in infants. The special problems encountered in the treatment of such patients are illustrated by three cases, a "Hangman's" fracture, a C6-7 fracture-dislocation, and an acute quadriparesis associated with dysgenesis of the posterior elements of C1-3.

Combined subarachnoid and subdural spinal hematoma following spinal puncture

A case of combined subarachnoid and subdural spinal hematomas secondary to lumbar puncture during myelography is described. Contributing factors to this particular syndrome are discussed and the separate clinical syndromes of epidural and subarachnoid spinal hematomas are described. The incidence of all spinal hematomas appears to be increasing, due to the combined factors of spinal trauma and anticoagulant therapy. Spinal hematomas typically present with severe and localized back pain, rapidly progressive myelopathy and a poor prognosis for functional recovery unless immediate decompression is performed.

Vascular pathology of the brain stem due to experimentally increased intracranial pressure: changes noted in the micro-and macrocirculation

✓ The neurological status and supra- and infratentorial intracranial pressures were studied in awake unsedated cats during expansion of a supratentorial mass. The pontomesencephalic portion of the brain stem was removed, serially sectioned, stained with sodium nitroprusside benzidine, and microscopically examined. Three types of vascular abnormality were seen: macrocirculation hemorrhages, microcirculation hemorrhages, and vascular stasis. As the supratentorial mass expanded and the intracranial pressure rose, there was a progression of vascular lesions from stasis to microcirculation hemorrhages, and finally to macrocirculation hemorrhages. The microcirculation hemorrhages occurred in stuporous animals, and the macrocirculation hemorrhages in comatose animals. Microcirculation hemorrhages were distributed primarily in the tectum, and macrocirculation hemorrhages were mainly in the tegmentum. Microcirculation hemorrhages first appeared in association with moderate to severe intracranial hypertension; macrocirculation hemorrhages were seen mainly with extreme intracranial hypertension. The clinical implications of these brain-stem vascular lesions are discussed.

The effects of mass-induced intracranial pressures on arterial hypertension and survival in awake cats

✓ Intracranial pressures above and below the tentorium, arterial blood pressure, heart rate, and respiratory rate were recorded continuously before, during, and after expansion of a supratentorial mass in awake unsedated cats. In general, as the mass enlarged, the intracranial pressure rose; however, considerable variation was observed among animals with respect to specific mass size and associated intracranial pressures. There was considerable variation in the relationship of supratentorial pressure to infratentorial pressure. No animal survived that had sustained a mass-induced pressure exceeding 1100 mm H2O, and survival was shorter with greater pressures. Systemic hypertension occurred always and only when the infratentorial pressure exceeded 600 mm H2O, regardless of the magnitude of the associated supratentorial intracranial pressure. The methodological limitations of previous studies of mass-induced intracranial hypertension appear to have been substantially reduced by the technique described.