Attention-deficit hyperactivity disorder (ADHD) and frontal-motor cortex disconnection.

Attention-Deficit Hyperactivity Disorder (ADHD) is a very common pediatric-neuropsychiatric entity of still unknown etiology, and is thus a topic of controversy. A neurological concept is presented in order to attain a better conceptualization of ADHD. This concept focuses on the frontal lobe as the inhibitor of excessive motor activity.

Acclimation of shade-developed leaves on saplings exposed to late-season canopy gaps.

We hypothesized that photoinhibition of shade-developed leaves of deciduous hardwood saplings would limit their ability to acclimate photosynthetically to increased irradiance, and we predicted that shade-tolerant sugar maple (Acer saccharum Marsh.) would be more susceptible to photoinhibition than intermediately shade-tolerant red oak (Quercus rubra L.).

Orderly oriented wire mesh: a novel porous coating.

As an alternative to commercially available porous beads and fiber metal mesh, a new porous coating, orderly oriented wire mesh (OOWM), was developed. Rectangular plugs, 10 x 5 x 5 mm with porous-coated beads, and four different OOWM configurations were inserted into bilateral femoral condyles of adult beagles. Dogs were sacrificed immediately after implantation, and at 4 weeks, 8 weeks, and 12 weeks postimplantation.

CT depiction of experimental liver tumors: contrast enhancement with hepatocyte-selective iodinated triglyceride versus conventional techniques.

Purpose: To compare findings at computed tomography (CT) enhanced with a hepatocyte-selective contrast agent (iodinated triglyceride) and/or iohexol and at CT during arterial portography (CTAP).

Materials And Methods: Rabbit livers were directly inoculated with VX2 carcinoma. Results were compared for five helical CT examinations: unenhanced CT, iohexol-enhanced CT (600 mg iodine per kilogram of body weight [mg I/kg]), CTAP (with iohexol [600 mg I/kg]), triglyceride-enhanced CT (126 mg I/kg), and dual-contrast-enhanced CT (triglyceride plus iohexol [425 mg I/kg]).

The radiological appearance of atherosclerotic popliteal artery aneurysms: the "dog-leg" sign.

The radiological appearance of popliteal aneurysms is described. Althought the lumen of the artery is often of normal diameter there is elongation of the vessel which frequently results in an acute "dog-leg". This sign has not been previously described.

Pre- and postimplantation dynamic mechanical properties of silastic HP-100 finger joints.

Dynamic mechanical properties of Silastic HP-100 finger joint implants were studied. Sixteen sections of unimplanted and 14 sections of retrieved implants were analyzed with standard thermal analysis techniques. Results show that implantation does not alter the viscoelastic properties of Silastic HP-100 elastomers.

Percutaneous pinning of distal radius fractures: a biomechanical study.

Mechanical testing of extra-articular distal radius fractures stabilized with percutaneous pins was performed. Twelve fresh-frozen unembalmed radii stripped of all soft tissues were used. An osteotomy with dorsal comminution was made 2.

Assessment of adrenal function in women heterozygous for adrenoleukodystrophy.

Adrenoleukodystrophy (ALD) is an X-linked recessive disorder that destroys the white matter of the brain and is associated with adrenal insufficiency. The prevalence of adrenal dysfunction in 71 women carriers of the X-linked ALD gene was studied. These subjects were identified initially on the basis of being obligate carriers of the X-linked trait by pedigree analysis and were confirmed by plasma very long chain fatty acid levels consistent with a heterozygote status.

Radiation-induced physical changes in UHMWPE implant components.

Post-irradiation aging of ultra-high molecular weight polyethylene (UHMWPE) is not well understood. Retrieval studies and in vitro aged specimens have shown oxidative changes along with increases in crystallinity. Critical analysis and review of the polymer science and polymer physics literature shows that while oxidation may be important during the first year post-irradiation, subsequent aging occurs because of initial gamma radiation-induced chain scission leading to eventual isothermal crystallization of polymer chains in the amorphous regions of the UHMWPE bulk.

Neuroanatomy in Rett syndrome: cerebral cortex and posterior fossa.

Rett syndrome (RS), a neurodevelopmental disorder of unknown etiology occurring almost exclusively in females, is characterized by autistic-like behavior, motor dysfunction, loss of language skills, dementia, and microcephaly. This study is a follow-up and extension of a previously reported neuroimaging study of patients with RS. We replicated previously reported findings with a larger patient population, and the volumetric MRI analysis was extended to include an analysis of neuroanatomy of the posterior fossa.

Thromboelastography in abruptio placentae.

The purpose of this study was to document thromboelastographic (TEG) changes in abruptio placentae and to compare these results with that of conventional tests used to monitor coagulation. This was a prospective study of 30 patients with abruptio placentae. All coagulation investigations including the TEG were performed on admission, immediately following delivery, and after periods of 4 hours and 24 hours.

The efficacy of phenytoin in eclampsia.

Although the Eclampsia Trial Collaborative Group reported that magnesium sulphate was more effective in preventing recurrent convulsions in eclampsia than phenytoin, confirmatory evidence that phenytoin is not useful as a prophylactic anticonvulsant agent in eclampsia is necessary. This prospective descriptive study enrolled 68 women with eclampsia. Recurrence of seizures occurred in 18 (26.

Abnormalities in neuronal maturation in Rett syndrome neocortex: preliminary molecular correlates.

In correspondence with the severe cognitive impairment and autistic features of Rett syndrome (RS), multiple anomalies of the cerebral cortex that include generalized reductions in dendritic arborizations and in cholinergic markers have been found. Considering the potential role of neurotransmitters in cortical differentiation, we have studied the relationship between cholinergic deficit and dendritic protein expression in RS and in a relevant animal model. Dendritic development is characterized by the sequential expression of cytoskeletal proteins whose levels remain relatively stable in adult life.

Rett syndrome: natural history and underlying disease mechanisms.

Rett syndrome (RS) is a neurological disorder that mainly, and possibly exclusively, affects girls. Diagnosis continues to be based upon a consistent constellation of clinical features observed in all of the patients worldwide. A biological marker has not been identified.

Unusual EEG theta rhythms over central region in Rett syndrome: considerations of the underlying dysfunction.

In 10 female patients (age 2-26 years) with clinical evidence of Rett Syndrome (RS), unusual and prominent rhythmical theta activity (4-5/sec or 5-6/sec) proved to be the outstanding EEG feature. This pattern was present in waking state and/or sleep. When it was noted in the waking state, the localization (vertex, central region and vicinity) and blocking responses to active or passive movements suggested a slow equivalent of Rolandic mu rhythm (in two patients associated with a posterior 10-12/sec alpha rhythm).

Nurses' perceptions of urinary catheter selection and management.

Nurses are often responsible for the initiation of catherization procedures for patients within the hospital or community setting. This nursing role requires contemporary information on catheter selection and problem solving in the maintenance of urinary catheters. A descriptive survey with a questionnaire sent to registered and enrolled nurses (N = 709) within an Australian metropolitan area health service was undertaken to determine their current knowledge level in relation to catheter care practices.

Initial stability of a modular uncemented, porous-coated femoral stem: a mechanical study.

A versatile modular hip system was used to evaluate the initial stability of a cementless femoral stem in anatomically consistent composite bones. Four implant bone configurations of varying proximal and distal fit/fill were tested. The implanted femurs were tested on an Instron 1331 materials testing machine in neutral loading and flexion loading; both translational micromotions and rotations of the implant relative to the bone were recorded on all three axes of motion, accounting for all 6 degrees of freedom of joint motion.

Cognitive and brain magnetic resonance imaging findings in adrenomyeloneuropathy.

Neuropsychological functioning and brain magnetic resonance imaging (MRI) were evaluated in 84 men with adrenomyeloneuropathy (AMN). MRI was normal in 61%, the "pure AMN" group, while 39%, the "cerebral AMN" group, showed brain white matter abnormalities. Except for mild deficits in psychomotor speed and visual memory, neuropsychological function was normal in pure AMN.

Mechanical stamping: a cause of fatigue fracture.

Failure analysis of a retrieved flexible intramedullary nail was performed by standard optical and scanning electron microscopy. Results show that the corrosion fatigue at the stamped label caused the nail fracture. The authors strongly recommend that the American Society for Testing of Materials standard F86-91 be modified to exclude mechanical stamping from the repertoire for labeling implants.

Dopamine transporters are markedly reduced in Lesch-Nyhan disease in vivo.

Dopamine (DA) deficiency has been implicated in Lesch-Nyhan disease (LND), a genetic disorder that is characterized by hyperuricemia, choreoathetosis, dystonia, and compulsive self-injury. To establish that DA deficiency is present in LND, the ligand WIN-35,428, which binds to DA transporters, was used to estimate the density of DA-containing neurons in the caudate and putamen of six patients with classic LND. Comparisons were made with 10 control subjects and 3 patients with Rett syndrome.

In vivo inflammatory response to silicone elastomer particulate debris.

Silicone elastomer particles (Silastic silicone elastomer, Dow Corning, Midland, MI), polymethylmethacrylate particles, and monosodium urate particles smaller than 10 microns were injected into a rat subcutaneous air pouch lined with synovial membrane-like cells. Inflammatory exudate from the air pouch was retrieved at 6 hours, 24 hours, 48 hours, and 72 hours after injection. White blood cell count, tumor necrosis factor, and prostaglandin E2 were measured in the exudate.