Achievement of Reactor-Relevant Performance in Negative Triangularity Shape in the DIII-D Tokamak

Plasma discharges with a negative triangularity (δ=-0.4) shape have been created in the DIII-D tokamak with a significant normalized beta (β_{N}=2.7) and confinement characteristic of the high confinement mode (H_{98y2}=1.2) despite the absence of an edge pressure pedestal and no edge localized modes (ELMs). These inner-wall-limited plasmas have a similar global performance as a positive triangularity (δ=+0.4) ELMing H-mode discharge with the same plasma current, elongation and cross sectional area. For cases both of dominant electron cyclotron heating with T_{e}/T_{i}>1 and dominant neutral beam injection heating with T_{e}/T_{i}=1, turbulent fluctuations over radii 0.5<ρ<0.9 were reduced by 10-50% in the negative triangularity shape compared to the matching positive triangularity shape, depending on the radius and conditions.

Bracing of the trunk and neck has a differential effect on head control during gait

During gait, the trunk and neck are believed to play an important role in dissipating the transmission of forces from the ground to the head. This attenuation process is important to ensure head control is maintained. The aim of the present study was to assess the impact of externally restricting the motion of the trunk and/or neck segments on acceleration patterns of the upper body and head and related trunk muscle activity. Twelve healthy adults performed three walking trials on a flat, straight 65-m walkway, under four different bracing conditions: 1) control-no brace; 2) neck-braced; 3) trunk-braced; and 4) neck-trunk braced. Three-dimensional acceleration from the head, neck (C7) and lower trunk (L3) were collected, as was muscle activity from trunk. Results revealed that, when the neck and/or trunk were singularly braced, an overall decrease in the ability of the trunk to attenuate gait-related oscillations was observed, which led to increases in the amplitude of vertical acceleration for all segments. However, when the trunk and neck were braced together, acceleration amplitude across all segments decreased in line with increased attenuation from the neck to the head. Bracing was also reflected by increased activity in erector spinae, decreased abdominal muscle activity and lower trunk muscle coactivation. Overall, it would appear that the neuromuscular system of young, healthy individuals was able to maintain a consistent pattern of head acceleration, irrespective of the level of bracing, and that priority was placed over the control of vertical head accelerations during these gait tasks.

Bowel injury

Small bowel and colon injury represents a significant portion of injuries sustained during penetrating trauma. These wounds may be tangential or through and through. Low velocity wounds are expected in the civilian setting, but high velocity wounds or shotgun injuries at close range can be seen as well. Most often these patients are explored and the injuries sustained can be managed effectively. Selective non-operative management for penetrating abdominal trauma is indicated only when there is no evidence of on-going hemorrhage or hollow viscus injury. The decision to abandon non-operative care must be made very early during the initial hospital course. In contrast bowel injury in blunt abdominal trauma may be difficult to detect. The clinical assessment and initial imaging will often define the extent of injury. However, patients with associated distracting injuries or subtle clinical signs will provide a greater challenge. This paper reviews the overall approach to patients with small bowel and colorectal trauma. It highlights published literature and makes recommendations regarding care based on injury assessment and the patients overall clinical condition. As surgeons we must use an evidenced based approach to undergird our clinical decision making. By doing so, we hope to bring improved outcomes and safer care to our patients.

Ventricular dilation and elevated aqueductal pulsations in a new experimental model of communicating hydrocephalus

In communicating hydrocephalus (CH), explanations for the symptoms and clear-cut effective treatments remain elusive. Pulsatile flow through the cerebral aqueduct is often significantly elevated, but a clear link between abnormal pulsations and ventriculomegaly has yet to be identified. We sought to demonstrate measurement of pulsatile aqueductal flow of CSF in the rat, and to characterize the temporal changes in CSF pulsations in a new model of CH. Hydrocephalus was induced by injection of kaolin into the basal cisterns of adult rats (n = 18). Ventricular volume and aqueductal pulsations were measured on a 9.4 T MRI over a one month period. Half of the animals developed ventricular dilation, with increased ventricular volume and pulsations as early as one day post-induction, and marked chronic elevations compared to intact controls (volume: 130.15 +/- 83.21 microl vs. 15.52 +/- 2.00 microl; pulsations: 114.51 nl +/- 106.29 vs. 0.72 +/- 0.13 nl). Similar to the clinical presentation, the relationship between ventricular size and pulsations was quite variable. However, the pulsation time-course revealed two distinct sub-types of hydrocephalic animals: those with markedly elevated pulsations which persisted over time, and those with mildly elevated pulsations which returned to near normal levels after one week. These groups were associated with severe and mild ventriculomegaly respectively. Thus, aqueductal flow can be measured in the rat using high-field MRI and basal cistern-induced CH is associated with an immediate change in CSF pulsatility. At the same time, our results highlight the complex nature of aqueductal pulsation and its relationship to ventricular dilation.

AAA+ Ring and linker swing mechanism in the dynein motor

Dynein ATPases power diverse microtubule-based motilities. Each dynein motor domain comprises a ring-like head containing six AAA+ modules and N- and C-terminal regions, together with a stalk that binds microtubules. How these subdomains are arranged and generate force remains poorly understood. Here, using electron microscopy and image processing of tagged and truncated Dictyostelium cytoplasmic dynein constructs, we show that the heart of the motor is a hexameric ring of AAA+ modules, with the stalk emerging opposite the primary ATPase site (AAA1). The C-terminal region is not an integral part of the ring but spans between AAA6 and near the stalk base. The N-terminal region includes a lever-like linker whose N terminus swings by ∼17 nm during the ATPase cycle between AAA2 and the stalk base. Together with evidence of stalk tilting, which may communicate changes in microtubule binding affinity, these findings suggest a model for dynein's structure and mechanism.

Structures of smooth muscle myosin and heavy meromyosin in the folded, shutdown state

Remodelling the contractile apparatus within smooth muscle cells allows effective contractile activity over a wide range of cell lengths. Thick filaments may be redistributed via depolymerisation into inactive myosin monomers that have been detected in vitro, in which the long tail has a folded conformation. Using negative stain electron microscopy of individual folded myosin molecules from turkey gizzard smooth muscle, we show that they are more compact than previously described, with heads and the three segments of the folded tail closely packed. Heavy meromyosin (HMM), which lacks two-thirds of the tail, closely resembles the equivalent parts of whole myosin. Image processing reveals a characteristic head region morphology for both HMM and myosin, with features identifiable by comparison with less compact molecules. The two heads associate asymmetrically: the tip of one motor domain touches the base of the other, resembling the blocked and free heads of this HMM when it forms 2D crystals on lipid monolayers. The tail of HMM lies between the heads, contacting the blocked motor domain, unlike in the 2D crystal. The tail of whole myosin is bent sharply and consistently close to residues 1175 and 1535. The first bend position correlates with a skip in the coiled coil sequence, the second does not. Tail segments 2 and 3 associate only with the blocked head, such that the second bend is near the C-lobe of the blocked head regulatory light chain. Quantitative analysis of tail flexibility shows that the single coiled coil of HMM has an apparent Young's modulus of about 0.5 GPa. The folded tail of the whole myosin is less flexible, indicating interactions between the segments. The folded tail does not modify the compact head arrangement but stabilises it, indicating a structural mechanism for the very low ATPase activity of the folded molecule.

Image-guided, direct convective delivery of glucocerebrosidase for neuronopathic Gaucher disease

OBJECTIVE

To determine if convection-enhanced delivery (CED) of glucocerebrosidase could be used to treat targeted sites of disease progression in the brain and brainstem of a patient with neuronopathic Gaucher disease while monitoring enzyme distribution using MRI.

METHODS

A CED paradigm in rodents (n = 8) and primates (n = 5) that employs co-infusion of a surrogate MRI tracer (gadolinium diethylenetriamine penta-acetic acid [Gd-DTPA]) with glucocerebrosidase to permit real-time monitoring of distribution was developed. The safety and feasibility of this delivery and monitoring paradigm were evaluated in a patient with type 2 Gaucher disease.

RESULTS

Animal studies revealed that real-time, T1-weighted, MRI of Gd-DTPA accurately tracked enzyme distribution during CED. Targeted perfusion of clinically affected anatomic sites in a patient with neuronopathic Gaucher disease (frontal lobe and brainstem) with glucocerebrosidase was successfully performed. Real-time MRI revealed progressive and complete filling of the targeted region with enzyme and Gd-DTPA infusate. The patient tolerated the infusions without evidence of toxicity.

CONCLUSIONS

Convection-enhanced delivery can be used to safely perfuse large regions of the brain and brainstem with therapeutic levels of glucocerebrosidase. Co-infused imaging surrogate tracers can be used to monitor and control the distribution of therapeutic agents in vivo. Patients with neuronopathic Gaucher disease and other intrinsic CNS disorders may benefit from a similar treatment paradigm.

Mammalian class I myosin, Myo1b, is monomeric and cross-links actin filaments as determined by hydrodynamic studies and electron microscopy

The class I myosin, Myo1b, is a calmodulin- and actin-associated molecular motor widely expressed in mammalian tissues. Analytical ultracentrifugation studies indicate that Myo1b purified from rat liver has a Stokes radius of 6.7 nm and a sedimentation coefficient, s(20,w), of 7.0 S with a predicted molar mass of 213 kg/mol. These results indicate that Myo1b is monomeric and consists primarily of a splice variant having five associated calmodulins. Molecular modeling based on the analytical ultracentrifugation studies are supported by electron microscopy studies that depict Myo1b as a single-headed, tadpole-shaped molecule with outer dimensions of 27.9 x 4.0 nm. Above a certain Myo1b/actin ratio, Myo1b bundles actin filaments presumably by virtue of a second actin-binding site. These studies provide new information regarding the oligomeric state and morphology of Myo1b and support a model in which Myo1b cross-links actin through a cryptic actin-binding site.

Use of negative stain and single-particle image processing to explore dynamic properties of flexible macromolecules

Flexible macromolecules pose special difficulties for structure determination by crystallography or NMR. Progress can be made by electron microscopy, but electron cryo-microscopy of unstained, hydrated specimens is limited to larger macromolecules because of the inherently low signal-to-noise ratio. For three-dimensional structure determination, the single particles must be invariant in structure. Here, we describe how we have used negative staining and single-particle image processing techniques to explore the structure and flexibility of single molecules of two motor proteins: myosin and dynein. Critical for the success of negative staining is a hydrophilic, thin carbon film, because it produces a low noise background around each molecule, and stabilises the molecule against damage by the stain. The strategy adopted for single-particle image processing exploits the flexibility available within the SPIDER software suite. We illustrate the benefits of successive rounds of image alignment and classification, and the use of whole molecule averages and movies to analyse and display both structure and flexibility within the dynein motor.

A second generation apparatus for time-resolved electron cryo-microscopy using stepper motors and electrospray

We describe here a second generation apparatus for studying transient reaction conformations in macromolecules and their complexes by electron cryo-microscopy. Reactions are trapped by rapid freezing in times ranging from a few milliseconds to tens of seconds after initiation. Blotting of the electron microscope grid and freezing it in liquid ethane uses computer controlled microstepping motors. For the fastest time resolution, a blotted grid containing a thin film of one reactant is sprayed with small droplets containing a second reactant just before freezing. The spray is produced electrically (electrospray), which gives a dense cloud of droplets <1 microm in diameter from the 1-2 microl of solution required per grid. A second method in which two solutions are first mixed by turbulent flow and then blotted prior to freezing is used for reactions with time courses >1s.

The structure of dynein-c by negative stain electron microscopy

Dynein ATPases contain six concatenated AAA modules within the motor region of their heavy chains. Additional regions of sequence are required to form a functional ATPase, which a previous study suggested forms seven or eight subdomains arranged in either a ring or hollow sphere. A more recent homology model of the six AAA modules suggests that these form a ring. Therefore both the number and arrangement of subdomains remain uncertain. We show two-dimensional projection images of dynein-c in negative stain which reveal new details of its structure. Initial electron cryomicroscopy shows a similar overall morphology. The molecule consists of three domains: stem, head, and stalk. In the absence of nucleotide the head has seven lobes of density forming an asymmetric ring. An eighth lobe protrudes from one side of this heptameric ring and appears to join the elongated cargo-binding stem. The proximal stem is flexible, as is the stalk, suggesting that they act as compliant elements within the motor. A new analysis of pre- and post-power stroke conformations shows the combined effect of their flexibility on the spatial distribution of the microtubule-binding domain and therefore the potential range of power stroke sizes. We present and compare two alternative models of the structure of dynein.

An environmental threshold for degree of phosphorus saturation in sandy soils

There is critical need for a practical indicator to assess the potential for phosphorus (P) movement from a given site to surface waters, either via surface runoff or subsurface drainage. The degree of phosphorus saturation (DPS), which relates a measure of P already adsorbed by a soil to its P adsorption capacity, could be a good indicator of that soil's P release capability. Our primary objective was to find a suitable analytical protocol for determining DPS and to examine the possibility of defining a threshold DPS value for Florida's sandy soils. Four farmer-owned dairy sprayfields were selected within the Suwannee River basin and soil profiles were randomly obtained from each site, as well as from adjacent unimpacted sites. The soil samples were divided either by horizon or depth, and DPS was determined for each soil sample using ammonium-oxalate (DPS(Ox)), Mehlich-1 (DPS(M1)), and Mehlich-3 (DPS(M3)) extracts. All methods of DPS calculations were linearly related to one another (r2 > 0.94). Relationships between water-soluble P and DPS indicate that the respective change points are: DPS(Ox) = 20%, DPS(M1) = 20%, and DPS(M3) = 16%. These relationships include samples from Ap, E, and Bt horizons, and various combinations thereof, suggesting that DPS values can be used as predictors of P loss from a soil irrespective of the depth of the soil within a profile. Taking into consideration the change points, confidence intervals, agronomic soil test values, and DPS values from other studies, we suggest replacing Mehlich-1 P values in the Florida P Index with the three DPS categories (DPS(M1) = <30, 30-60, and >60%) to assign different P loss ratings in the P Index.

Dynein structure and power stroke

Dynein ATPases are microtubule motors that are critical to diverse processes such as vesicle transport and the beating of sperm tails; however, their mechanism of force generation is unknown. Each dynein comprises a head, from which a stalk and a stem emerge. Here we use electron microscopy and image processing to reveal new structural details of dynein c, an isoform from Chlamydomonas reinhardtii flagella, at the start and end of its power stroke. Both stem and stalk are flexible, and the stem connects to the head by means of a linker approximately 10 nm long that we propose lies across the head. With both ADP and vanadate bound, the stem and stalk emerge from the head 10 nm apart. However, without nucleotide they emerge much closer together owing to a change in linker orientation, and the coiled-coil stalk becomes stiffer. The net result is a shortening of the molecule coupled to an approximately 15-nm displacement of the tip of the stalk. These changes indicate a mechanism for the dynein power stroke.

Polymorphism of the serotonin-2A receptor gene (HTR2A) associated with childhood attention deficit hyperactivity disorder (ADHD) in adult women with seasonal affective disorder

INTRODUCTION

Several lines of research point to a possible overlap between seasonal affective disorder (SAD) and attention deficit hyperactivity disorder (ADHD), particularly in females. There is also emerging evidence that variation of the 5-HT2A receptor gene (HTR2A) contributes to both SAD and ADHD. The current study investigated whether variation in HTR2A was associated with symptoms of childhood ADHD in adult women with SAD.

METHOD

Sixty-six women with SAD were administered the Wender-Utah Rating Scale (WURS), which retrospectively assesses childhood ADHD, as part of an ongoing genetic study of SAD. WURS scores were compared across the three genotypic groups defined by the T102C polymorphism of HT2RA.

RESULTS

Analysis of variance indicated a significant difference in mean 25-item WURS scores across the three genotypic groups (p = 0.035). Post-hoc tests revealed that the C/C genotypic group had a significantly higher mean score than both the T/T group and T/C group. Based on previously established WURS criteria, 38% of subjects with the C/C genotype, and none with the T/T genotype, had scores consistent with childhood ADHD.

LIMITATIONS

The current sample size is small, and childhood ADHD diagnoses were based on retrospective recall.

CONCLUSION

These preliminary results suggest a possible association between variation in HTR2A, childhood ADHD, and the later development of SAD in women.

Polymorphism of the serotonin 5-HT1B receptor gene (HTR1B) associated with minimum lifetime body mass index in women with bulimia nervosa

BACKGROUND

Preclinical research has shown that the serotonin-1B receptor has important modulatory effects on feeding behavior and thus body weight. In the current study, we examined whether genetic variation of the serotonin-1B receptor was associated with minimum and maximum lifetime body mass indices (BMIs) in a sample of women with bulimia nervosa (BN).

METHODS

Ninety-eight women with BN were genotyped based on the G861C polymorphism of the serotonin-1B receptor gene (HTR1B). Minimum and maximum lifetime BMIs were compared across the three genotypic groups using analysis of variance.

RESULTS

There was a highly significant difference in minimum lifetime BMI across the three genotypic groups (p =.001). Both the G/C and C/C genotypes were associated with significantly lower minimum lifetime BMIs than was the G/G genotype. Maximum lifetime BMI was not significantly different across groups. These results were not attributable to different lifetime rates of anorexia nervosa across the three genotypic groups.

CONCLUSIONS

These preliminary findings suggest a possible association between HTR1B genetic polymorphism and minimum lifetime BMI in women with BN. These findings may shed light on why, in response to dieting, some BN patients achieve lower BMIs, whereas others have a natural limitation to their weight loss. Pending replication in a larger sample, these findings point to a possible genetic factor of fundamental importance to the BN population.

Ruptured intracranial mycotic aneurysm: an unusual infectious complication following craniofacial surgery

The case of a child with Apert syndrome is presented in which the development and rupture of an intracranial mycotic aneurysm occurred secondary to multiple infectious complications following craniofacial surgery. An endovascular procedure was utilized in an attempt to embolize the aneurysm and parent vessel. The patient recovered from her infections, but retained a residual right hemiparesis and left cranial nerve III palsy at the time of discharge. To our knowledge, this is the first report of a mycotic aneurysm developing after a craniofacial procedure. Risk factors leading to aneurysm formation in this case are presented, as well as a literature review of neurological complications following craniofacial surgery.

History of ventriculostomy

Ventriculoscopy and neuroendoscopy had their beginnings in the early part of the twentieth century, when neurosurgeons were motivated by a desire to control hydrocephalus. The development of endoscopy was initially hampered by significant complications. When extracranial shunting became commonplace, endoscopy was essentially discarded by neurosurgeons. It was because of the continuing problems with shunting that a renewed interest in neuroendoscopy developed. Specific indications for various procedures have now been developed, and increasing success is being realized by the use of endoscopic procedures.

A functional polymorphism of the cytochrome P450 1A2 (CYP1A2) gene: association with tardive dyskinesia in schizophrenia

Tardive dyskinesia (TD) is a common and potentially irreversible side effect associated with long-term treatment with typical antipsychotics. Approximately, 80% or more of patients with schizophrenia are smokers. Smoking is a potent inducer of the CYP1A2 enzyme, and is known to cause a significant decrease in plasma concentrations of some antipsychotics. Therefore, person-to-person differences in the extent of CYP1A2 induction by smoking may contribute to risk for the development of TD. Recently, a (C-->A) genetic polymorphism in the first intron of the CYP1A2 gene was found to be associated with variation in CYP1A2 inducibility in healthy volunteer smokers. The aim of this study was to test the clinical importance of the (C-->A) polymorphism in CYP1A2 in relation to TD severity. A total of 85 patients with schizophrenia were assessed for TD severity using the Abnormal Involuntary Movement Scale (AIMS), and were subsequently genotyped for the (C-->A) polymorphism in CYP1A2. The mean AIMS score in patients with the (C/C) genotype (associated with reduced CYP1A2 inducibility) was 2.7- and 3.4-fold greater than in those with the (A/C) or (A/A) genotype, respectively (F[2,82] = 7.4, P = 0.0007). Further, a subanalysis in the 44 known smokers in our sample, revealed a more pronounced effect. The means AIMS score in smokers was 5.4- and 4. 7-fold greater in (C/C) homozygotes when compared to heterozygotes and (A/A) homozygotes, respectively (F[2,41] = 3.7, P = 0.008). These data suggest that the (C-->A) genetic polymorphism in the CYP1A2 gene may serve as a genetic risk factor for the development of TD in patients with schizophrenia. Further studies in independent samples are warranted to evaluate the applicability of our findings to the general patient population receiving antipsychotic medications.

Two-headed binding of a processive myosin to F-actin

Myosins are motor proteins in cells. They move along actin by changing shape after making stereospecific interactions with the actin subunits. As these are arranged helically, a succession of steps will follow a helical path. However, if the myosin heads are long enough to span the actin helical repeat (approximately 36 nm), linear motion is possible. Muscle myosin (myosin II) heads are about 16 nm long, which is insufficient to span the repeat. Myosin V, however, has heads of about 31 nm that could span 36 nm and thus allow single two-headed molecules to transport cargo by walking straight. Here we use electron microscopy to show that while working, myosin V spans the helical repeat. The heads are mostly 13 actin subunits apart, with values of 11 or 15 also found. Typically the structure is polar and one head is curved, the other straighter. Single particle processing reveals the polarity of the underlying actin filament, showing that the curved head is the leading one. The shape of the leading head may correspond to the beginning of the working stroke of the motor. We also observe molecules attached by one head in this conformation.

Genetic studies in neural tube defects. NTD Collaborative Group

Neural tube defects (NTD) are one of the most common birth defects and are caused by both environmental and genetic factors. The approach to identifying the genes predisposing to NTD, through linkage analysis and candidate gene analysis, is reviewed along with characteristics of a large, nationally ascertained cohort of families. Results from specific assessments of p53, PAX3 and MTHFR failed to suggest that these genes play a major role in NTD development in these families. Advances in genetic laboratory and statistical techniques have made this a prime opportunity for investigation into the causes of complex disorders, such as NTD. However, traditional approaches may prove to be challenging due to the difficulty of ascertaining samplable multiplex families.

Applicability of personality disorder criteria to hospitalized adolescents: evaluation of internal consistency and criterion overlap

OBJECTIVE

The authors examined the applicability of personality disorder criteria to adolescent inpatients by evaluating internal consistency and criterion overlap.

METHOD

Thirty-eight adolescents and 28 adults were assessed with the Personality Disorder Examination. Within-category cohesiveness (internal consistency) of the criteria was evaluated by examining intercriterion correlations as well as coefficient alpha. In addition, between-category criterion overlap was evaluated by examining "intercategory" intercriterion correlations between all pairs of disorders. Separate analyses were conducted for adolescents and adults, and the groups were compared.

RESULTS

Internal consistency appeared to be lower in adolescents, as measured by intercriterion correlation and coefficient alpha, with the largest differences being identified for most cluster B disorders. Intercategory analysis indicated that criterion overlap may be greater among adolescents.

CONCLUSIONS

Overall, this psychometric analysis suggests that there may be limitations to the DSMs approach to categorizing personality disorders. For both adolescents and adults, modest degrees of within-category cohesiveness (internal consistency) and between-category criterion overlap were observed. Comparatively, personality disorder criteria in adolescents tended to have lower internal consistency and less discriminant validity. The data raise questions about the construct validity of these disorders--or the applicability of these criteria--within this age group.

An audit of magnetic resonance imaging in the paediatric orthopaedic setting

AIMS

To determine when magnetic resonance imaging (MRI) is helpful in the management of a selected group of paediatric orthopaedic patients.

METHODS

A retrospective analysis of 131 MRI scans was undertaken with allocation into seven categories based on clinical presentation.

RESULTS

MRIs performed for spinal, congenital and intra-articular pathology, as well as for growth plate assessment correlated well with subsequent clinical and/or surgical findings. Three of ten MRIs (30%) incorrectly assessed whether a foreign body was present with a sensitivity of 0.60 and specificity of 0.80. Three of 20 MRIs (15%) could not accurately distinguish between oedema/effusion and frank infection. Here sensitivity was 1.00 and specificity was 0.73. MRIs performed for assessment of tumours were accurate with respect to margins and extent. Assessment of pathology with MRI was never the indication for MRI, thus it was not surprising that in four of 27 soft tissue tumours (sensitivity of 0.88 and specificity of 0.63) MRI did not correlate with subsequent histological findings.

CONCLUSIONS

MRI plays an important role in the assessment of a wide range of musculo-skeletal pathology. MRI does not, and could not be expected to, replace the need for incisional biopsy for tumour diagnosis. It must be used with caution where tissues have been previously explored for foreign bodies. Interpretation of MRI in musculoskeletal infection must consider its timing in the evolution of the patient's infection.

A computer-controlled spraying-freezing apparatus for millisecond time-resolution electron cryomicroscopy

Apparatus is described for the kinetic investigation of biological reactions by electron cryomicroscopy with time resolution on the order of milliseconds. This involves layering a grid with one reactant and then spraying on a second reactant immediately before freezing. Two-stage mixing can be achieved by mixing two solutions, holding them in a delay line for a preset interval, and then spraying the aged solution onto a grid carrying a third reactant. The individual steps of these procedures are under software control and can be adjusted independently. Spray-freezing is widely applicable since solutions of small molecules, proteins, and protein assemblies can be delivered as aerosols. Thus the method can be used to study both the effects of small molecules on macromolecules and for monitoring protein-protein interactions. It may also be useful in other situations, for instance in light microscopy.

Endoscopic third ventriculostomy: an outcome analysis

Endoscopic third ventriculostomy (ETV) has gained widespread acceptance as an effective way to manage hydrocephalus in selected patients. To determine which patient groups have the highest chance of successful ETV, a retrospective case review was performed. From June 1992 to December 1996, 97 patients underwent a total of 98 ETVs at our institution. There were 59 males and 38 females with a mean age of 8.1 years (range 1 day to 29.5 years). Twenty-six of 98 procedures (26%) were abandoned due to either unfavorable anatomy, inability to perform a cisternostomy, or hemorrhage. Follow-up data was available in 92 patients for a mean of 24.2 months. The rate of successful ETV in 71 patients, with either complete shunt avoidance or removal, varied widely by diagnosis and patient age. The highest success rates were achieved in patients with aqueductal stenosis, tectal plate tumor, myelomeningocele and posterior fossa tumor. Complications included one transient herniation syndrome, one basilar artery perforation, 2 cases of ventriculitis, one transient decrease in level of consciousness, and one transient hemiparesis. We feel these results support the continued use of ETV in only carefully selected patients with hydrocephalus.

Penetrating neck trauma: lack of universal reporting guidelines

Penetrating neck injuries constitute a heterogeneous group. Two different classifications of zones of the neck exist in trauma literature. Injuries crossing the midline are not accurately reported. Records of 50 patients with stab wounds (30), gunshot wounds (GSWs; 17), and shotgun wounds (SGWs; 3) were reviewed. Injuries involved zone I in 8 patients, zone II in 37 patients, zone III in 8 patients, posterior triangle in 6 patients, and multiple zones in 5 patients. All 11 patients with transcervical GSWs and SGWs sustained vascular or aerodigestive injuries and had longer hospital stays (14.0 +/- 2.6 days) compared with patients with other GSWs (6.6 +/- 2.0 days) and stab wounds (3.6 +/- 0.5 days). We emphasize the lethal potential of transcervical GSWs and SGWs. We suggest that these particular injuries be reported separately. We recommend the universal adoption of one system of classification of neck zones.

Frequency of personality disorders in two age cohorts of psychiatric inpatients

OBJECTIVE

The authors examined the frequency of DSM-III-R personality disorders in adolescent and young adult psychiatric inpatients.

METHOD

Structured diagnostic interviews were reliably performed with a series of 255 consecutively admitted inpatients (138 adolescents and 117 young adults).

RESULTS

Most personality disorders were diagnosed in similar frequencies in the two study groups. Passive-aggressive personality disorder was diagnosed with lower frequency and dependent personality disorder with higher frequency in the young adult than in the adolescent group.

CONCLUSIONS

The isomorphism of relative frequencies among psychiatric inpatients suggests that what is seen in adolescents are valid forms of most adult personality disorders.

Basilar artery perforation as a complication of endoscopic third ventriculostomy

The morbidity and mortality associated with third ventriculostomy has decreased significantly over the past 75 years since its introduction by Walter Dandy. Now more commonly performed using an endoscopic method, the significant morbidity of third ventriculostomy has dropped to approximately 5%; essentially that associated with ventriculoscopy in general. However, the possible complication of massive subarachnoid hemorrhage resulting from perforation of the basilar artery or its branches in the course of fenestration of the floor of the third ventricle has only recently been reported. In our case, subsequent to a vascular injury, a pseudoaneurysm developed at the site of vascular perforation, which was then appropriately controlled. The patient has since made a full recovery. Our goal is to remind the endoscopist of this unusual complication and to discuss our management strategies.

Flexibility within myosin heads revealed by negative stain and single-particle analysis

Electron microscopy of negatively stained myosin has previously revealed three discrete regions within the heads of the molecule. However, despite a probable resolution of approximately 2 nm, it is difficult to discern directly consistent details within these regions. This is due to variability in both head conformation and in staining. In this study, we applied single-particle image processing and classified heads into homogeneous groups. The improved signal-to-noise ratio after averaging these groups reveals substantially improved detail. The image averages were compared to a model simulating negative staining of the atomic structure of subfragment-1 (S1). This shows that the three head regions correspond to the motor domain and the essential and regulatory light chains. The image averages were very similar to particular views of the S1 model. They also revealed considerable flexibility between the motor and regulatory domains, despite the molecules having been prepared in the absence of nucleotide. This flexibility probably results from rotation of the regulatory domain about the motor domain, where the relative movement of the regulatory light chain is up to 12 nm, and is most clearly illustrated in animated sequences (available at http://www.leeds.ac.uk/chb/muscle/myosinhead.htm l). The sharply curved conformation of the atomic model of S1 is seen only rarely in our data, with straighter heads being more typical.

Cerebral trauma-induced changes in corpus striatal dopamine receptor subtypes

A device designed specifically for mild to severe concussions was used to produce quantitative experimental blunt brain injury in male Wistar rats. We have examined the effects of varying magnitudes of cerebral trauma on the maximal binding capacity (Bmax) of D1 and D2 dopamine (DA) receptors. The Bmax for each receptor subtype was obtained from Scatchard analyses of [3H]-SCH 23390 and [3H]Spiperone binding to striatal membrane. Anesthetized rats were injured--one, two, or three times--once every 24 h, with either a 68- or 268-g rubber-headed reflex hammer accelerated from a predetermined distance. Uninjured nonanesthetized (NA) and anesthetized (A) rats served as controls. No significant difference in receptor density was observed between NA and A rats for each receptor subtype. Immediately (0 h) following injury from the 68-g hammer weight, the density of D1 receptors decreased (50%), then increased (30%) above control levels by 24 h. The same pattern was observed with the 268-g hammer weight. Analysis of variance (ANOVA) showed that there was no overall effect of number of injuries or treatment on the density of D1 and D2 receptor subtypes. However, there was an interaction of both variables on the D1, but not D2, receptor subtype. Partial ANOVA for receptor densities after rats were injured either one, two, or three times showed that receptor density was altered only after the rats were injured one time. These results suggest that striatal DA D1 receptors are downregulated and then upregulated following isolated injury to the cerebral cortex.

Controlled study of psychiatric comorbidity in psychiatrically hospitalized young adults with substance use disorders

OBJECTIVE

The purpose of this study was to examine DSM-III-R axis I and axis II comorbidity in psychiatrically hospitalized young adults with substance use disorders.

METHOD

Structured diagnostic interviews were given to 117 consecutive inpatients. Seventy patients with substance use disorders and 47 patients without substance use disorders were compared.

RESULTS

High rates of co-occurrence of axis I disorders were observed, but no disorder coexisted in the group with substance use disorders at a significantly higher rate than in the group without substance use disorders. Among axis II disorders, borderline personality disorder was diagnosed significantly more frequently in the group with substance use disorders.

CONCLUSIONS

Significant additional diagnostic co-occurrence, defined as comorbidity, was observed only between borderline personality disorder and substance use disorders. The use of a relevant psychiatric comparison group allows for finer distinctions between covariation based on shared severity and comorbidity possibly based on shared pathophysiology.

Choroid plexus papilloma and cysts in the Aicardi syndrome: case reports

Two female infants with callosal agenesis, infantile spasms, chorioretinal lacunae, optic disc colobomas and cortical heterotopias were diagnosed with Aicardi syndrome. A choroid plexus papilloma was found in one patient, and choroid plexus cysts were found in the other. Choroid plexus lesions are common findings in the Aicardi syndrome and are discussed in this paper.

Delayed presentation of popliteal artery pseudoaneurysm following blunt trauma

Popliteal artery pseudoaneurysms are not uncommon. They may result from penetrating or blunt trauma, arterial reconstructive surgery, invasive diagnostic or surgical orthopedic procedures, and perigenicular neoplasia. We report two patients with popliteal artery pseudoaneurysm diagnosed 3 months and 3 weeks, respectively, after blunt trauma. These two patients as well as many patients reported in the literature had palpable distal pulses and no obvious clinical signs of arterial injury following various forms of trauma. Arteriography in these circumstances is usually abandoned because of the low yield and the possible risk of complications. However, as we illustrate in this report, noninvasive diagnostic modalities such as duplex ultrasound and magnetic resonance arteriography are both safe and accurate for early detection of popliteal artery pseudoaneurysm. Once diagnosed, standard vascular reconstruction should be performed to prevent potential complications.

Diagnostic comorbidity in hospitalized adolescents with conduct disorder

We compared the diagnostic comorbidity of DSM-III-R axis I and axis II disorders in a sample of hospitalized adolescents with conduct disorder (CD) and a comparison group of hospitalized adolescents without conduct disorder (non-CD). Of 138 consecutively evaluated adolescents, 76 patients met criteria for CD and 62 did not. On axis I, CD was significantly comorbid with attention-deficit hyperactivity disorder (ADHD) and substance use disorders (SUDs). None of the personality disorders assessed showed differential association with CD. The comorbid relationships found within this sample suggest a strong association between CD, ADHD, and SUD in hospitalized teenagers. This finding underscores the clinical importance of conducting a thorough developmental assessment and, when indicated, of treating ADHD and SUD in conduct-disordered adolescents.

Reduced cerebral vasomotor reactivity as an indicator of postoperative confusion

Surgical intervention in elderly patients carries a high risk. A frequent problem with surgery in these patients is the occurrence of a temporary confusional state, which increases both the risk of postoperative complications and the need for intensive care. We hypothesised that, in part, temporary confusional state results from cerebral hypoxia occurring in response to blood pressure fluctuations during surgery. To assess whether disruption of autoregulation of cerebral blood vessels plays a role in temporary confusional state, we studied 31 patients over 55 years of age, using the Doppler-carbon dioxide test. We determined whether vasomotor reactivity could be used diagnostically to identify those patients most likely to experience temporary confusional state. Blood flow velocity in the middle cerebral artery was detected using Doppler ultrasound, and hypercapnia was induced by breathing carbon dioxide until an end-tidal concentration of 8.0% by volume was reached. Vasomotor reactivity was calculated on the basis of the changes in blood flow velocity in response to the increase in carbon dioxide. Temporary confusional state was assessed using the Syndrome Short Test (Syndrom-Kurztest). We found that resting blood flow velocity was inversely related to age (p < 0.05). In addition, there was a significant inverse correlation between vasomotor reactivity and temporary confusional state (p < 0.05). These data indicate that vasomotor reactivity, as measured by the Doppler-carbon dioxide test, is a reliable tool to identify patients at risk for postoperative psychological disturbances.

Psychiatric comorbidity differences in male and female adult psychiatric inpatients with substance use disorders

To examine gender differences in the co-occurrence of DSM-III-R axis I disorders and axis II personality disorders in young adult psychiatric inpatients with substance use disorders (SUDs), a consecutive series of 70 inpatients (33 men and 37 women) with SUD were reliably assessed with structured diagnostic interviews. Higher rates of dysthymia and eating disorders were observed in SUD females and higher rates of cluster A personality disorders were observed in SUD males. No gender differences were found for depression or anxiety in our SUD inpatients; these findings contrast with gender ratios for these disorders in the general population. In conclusion, relatively few gender differences were found in young adult inpatients with SUD, even where they would be expected based on general population gender patterns.

Personality disorders in adolescents with major depression, substance use disorders, and coexisting major depression and substance use disorders

This study examined the presence of personality disorders in adolescent inpatients with major depression (MDD; n = 45), substance use disorders (SUD; n = 27), or both disorders combined (MDD-SUD; n = 42). A consecutive series of patients were given structured diagnostic interviews for Axes I and II disorders. The groups did not differ with regard to age, gender, ethnicity, socioeconomic status, psychiatric history, or global assessment of functioning. Borderline personality disorder was diagnosed more frequently in the MDD-SUD group than in the MDD or the SUD groups.

Personality disorders in adolescents with major depression, substance use disorders, and coexisting major depression and substance use disorders

This study examined the presence of personality disorders in adolescent inpatients with major depression (MDD; n = 45), substance use disorders (SUD; n = 27), or both disorders combined (MDD-SUD; n = 42). A consecutive series of patients were given structured diagnostic interviews for Axes I and II disorders. The groups did not differ with regard to age, gender, ethnicity, socioeconomic status, psychiatric history, or global assessment of functioning. Borderline personality disorder was diagnosed more frequently in the MDD-SUD group than in the MDD or the SUD groups.

Experimental model: change in the posterior fossa with surgically induced spina bifida aperta in mouse

On the basis of experimental studies on mouse embryos in which spina bifida development of the brain ventricular system. Mouse embryos were exposed and surgically treated at gestation day 12 to produce spina bifida aperta, and operated embryos were cultured exo utero in the peritoneal cavity of the pregnant dam. Embryos were harvested at gestation day 14. Open neural tube defects resulted in 7 out of 10 embryos surviving surgery. Histological examination revealed that the sizes of ventricles in both the supra- and infratentorial compartments were greatly reduced in embryos with spina bifida aperta compared with control embryos. This result supports the hypothesis that leakage of cerebrospinal fluid through the opening of the caudal spine may be a major cause of brain abnormalities in patients with myelomeningocele.

The role of "one-shot" intravenous pyelogram in evaluation of penetrating abdominal trauma

The role of limited "one-shot" intravenous pyelogram (IVP) in patients sustaining proximity penetrating trauma is not well defined, although formal IVP remains the "gold standard" for evaluating possible urological injuries. This retrospective review evaluates the efficacy and usefulness of limited one-shot IVP in penetrating abdominal trauma patients who are suspected of having urological injuries. The charts of 40 patients with penetrating abdominal trauma who had one-shot IVP performed in the emergency room at presentation were reviewed. Of the total, 36 patients had gunshot wounds and only 4 patients had stab wounds. Mean Penetrating Abdominal Trauma Index was 15.7, with 47.5 per cent of patients in shock. Only 2 out of 10 urological injuries were detected by one-shot IVP. The positive predictive value of limited one-shot IVP was only 20 per cent, with sensitivity 25 per cent and specificity 76.2 per cent. The results of the one-shot IVP did not influence the decisions for laparotomy in any of the 35 (87.5%) patients who underwent exploratory laparotomy. In the two patients with positive one-shot IVPs who had urological injuries, the decision to operate was again determined by the presence of other associated intra-abdominal injuries. Eighty per cent of patients with normal one-shot IVP findings had renal injuries not detected by one-shot IVP, and 20 per cent of patients with abnormal IVP findings had no intraoperative evidence of renal injury. The presence of gross hematuria appeared to correlate with the presence of significant urological injuries. We therefore conclude that limited one-shot IVP is of no significant value in assessing penetrating abdominal trauma patients who subsequently undergo exploratory laparotomy for other associated intra-abdominal injuries, and indeed, the delay imposed, before definitive operative intervention in potentially unstable patients, is unjustified.

Three-dimensional ultrasound angiography (power mode) for the quantification of carotid artery atherosclerosis

Three-dimensional (3D) ultrasound angiography was performed to diagnose carotid artery atherosclerosis. Thirty-five patients (15 women, 20 men) with a history of cerebrovascular disease were examined using conventional color-coded Doppler ultrasound and 3D ultrasound angiography. Carotid stenosis was initially diagnosed using continuous-wave Doppler ultrasound. To determine intraobserver and interobserver reliabilities, 21 patients were evaluated using 3D ultrasound on three occasions. Sixty-five percent of patients were diagnosed with stenosis of more than 50%. Twenty-two percent of plaques had a smooth surface, 72.9% were ulcerated, and 5.1% were indeterminate. Data collection for 3D imaging required 5 minutes per patient, whereas image processing and plaque volume quantification required 30 minutes. Plaque volume ranged from 0.053 to 0.685 ml. The intraobserver and interobserver variabilities were 4.16 and 5.87%, respectively (r = 0.96, p < 0.0001; r = 0.89, p < 0.0001). 3D Color Doppler and 3D ultrasound angiography assessments of plaque volume differed by 8.5%. Plaques were more precisely differentiated using 3D ultrasound, and plaque volume quantification was less affected by echo shadowing after 3D reconstruction. In comparison to other techniques for the quantification of atherosclerotic lesions. 3D ultrasound angiography offers a more precise quantitative method for prospective, clinical studies of atherosclerosis.

Astrocytoma and pineoblastoma arising sequentially in the fourth ventricle of the same patient. Case report and molecular analysis

The sequential appearance of two different brain tumors in the same patient without intervening radiation or chemotherapy is a rare event, most often seen in hereditary cancer syndromes. We present one such case of sequential tumors, along with their molecular analysis. A 17-year-old male presented with a pilocytic astrocytoma arising in the fourth ventricle at the pontomedullary junction. Six and one half years later, a pineoblastoma was discovered in the fourth ventricle, rostral to the first tumor site. Both tumors were treated by gross-total surgical resection. Following resection of the pineoblastoma, the patient underwent craniospinal irradiation and systemic chemotherapy. Single-strand conformation polymorphism analysis showed that the patient had neither a germ-line mutation nor a somatic tumor mutation in the p53 tumor suppressor gene. Coupled with the lack of a family history of cancer, these data suggest that these were not manifestations of Li-Fraumeni syndrome, but rather two sporadic tumors which arose via a p53-independent mechanism.

Gender differences in personality disorders in psychiatrically hospitalized young adults

We examined gender differences in DSM-III-R personality disorders in psychiatrically hospitalized young adults. Structured diagnostic interviews were reliably performed on a consecutive series of 118 inpatients. Men were significantly more likely to meet criteria for cluster A, schizotypal, and antisocial personality disorders. To reduce variability due to axis I heterogeneity, we retested for gender differences in a subgroup of patients with major depression. Depressed men were more likely to meet criteria for cluster A, schizotypal, and cluster C personality disorders. Women were not observed to have a higher frequency of any personality disorder than men in either study group.

Basilar artery blood flow during head rotation in vertebrobasilar ischemia

PATIENTS AND METHODS

Forty-six patients with vertebrobasilar ischemia and 40 control subjects were examined during head rotation using transcranial Doppler ultrasonography.

RESULTS

In the control group, no difference in blood flow velocity through the BA was found between the neutral and rotated positions. Based on these data, a blood flow reduction in the BA of more than 20% was considered to be significantly abnormal (p < 0.01). In three of 46 patients no signal was detectable in the BA using TCD. The reduction in blood flow velocity through the BA during head rotation was strongly dependent on the condition of the VA; none of 23 patients without atherosclerotic lesions or hypoplasia of the VA developed a significant reduction in blood flow through the BA. Two of 11 patients with unilateral VA lesions had significantly reduced blood flow in the BA (27% and 31%), although both were asymptomatic. Five of nine patients with bilateral VA lesions showed a significant reduction in blood flow through the BA (mean = 52%, minimum = 30%), and four of these developed clinical symptoms such as vertigo or diplopia during the rotation maneuver.

CONCLUSION

These data suggest that patients with uni- or bilateral lesions of the VA are at risk for developing clinically relevant reductions in blood flow through the BA during head rotation. Because not all patients with VA lesions developed reduced blood flow velocity, we conclude that individual vascular mechanisms must play an important compensatory role.

Gender differences in personality disorders in psychiatrically hospitalized adolescents

OBJECTIVE

The authors examined gender differences in DSM-III-R personality disorders in adolescent psychiatric inpatients.

METHODS

Structured diagnostic interviews were reliably performed with a series of 138 consecutively admitted adolescent inpatients. To reduce variability due to heterogeneity of axis I diagnoses, a subgroup of 87 patients with major depression was retested for gender differences.

RESULTS

Females were significantly more likely than males to meet the criteria for borderline personality disorder. Narcissistic personality disorder was diagnosed only in males. A similar pattern was observed in the subgroup of patients with major depression.

CONCLUSIONS

The findings suggest potentially important gender differences in personality disorders in adolescent inpatients.

Spinal stenosis after total lumbar laminectomy for selective dorsal rhizotomy

Knowledge of long-term outcome and complications of selective dorsal rhizotomy is limited due to the relatively recent introduction of the procedure. We describe 2 patients with cerebral palsy who developed lumbar spinal stenosis several years after selective dorsal rhizotomy. These patients also had substantial lateral trunk sway during gait and walked for several years with limited assistive devices. This abnormal gait pattern in combination with the changes from the selective dorsal rhizotomy may lead to the development of spinal stenosis.