Congenital cerebral and cerebrovascular anomalies: magnetic resonance imaging

Magnetic resonance is the imaging modality of choice for the evaluation of infants and children with known or suspected cerebral and cerebrovascular abnormalities. Entities described include cephaloceles, holoprosencephaly, dysgenesis of corpus callosum, and anomalies of neuronal migration. Congenital vascular lesions described include aneurysm, arteriovenous malformation, cavernous malformation, and Galenic malformations.

Nature vs. nurture: two brothers with schizophrenia

TOPIC

The nature vs. nurture argument as it pertains to two brothers.

PURPOSE

To explore the synergistic effects of heritability and environment in the cases of two brothers with schizophrenia.

SOURCES

Review of the literature and the authors' clinical experience.

CONCLUSIONS

The nature vs. nurture dichotomy may not be as relevant as looking at the interaction between these two forces.

Ophthalmologic disease in children

MR imaging has become essential in the evaluation of a spectrum of ophthalmologic diseases in children. Orbit, globe, optic nerve, and optic tract disease processes that are frequently evaluated by MR imaging include congenital malformations, and inflammatory, neoplastic, and traumatic lesions. MR imaging evaluation aids in differentiating these lesions for diagnosis, the extent of disease, treatment planning, follow-up, and prognosis.

Immobilizing a Fluorescent Dye Offers Potential to Investigate the Glass/Resin Interface

Silane coupling agents are commonly applied to glass fibers to promote fiber/resin adhesion and enhance durability in composite parts. In this study, a coupling agent multilayer on glass was doped with trace levels of the dimethylaminonitrostilbene (DMANS) fluorophore. The fluorophore was immobilized on the glass surface by tethering the molecule to a triethoxy silane coupling agent, creating the DMANS/silane coupling agent molecule (DMSCA). DMSCA was then diluted with commonly used coupling agents and grafted to a glass microscope coverslip to create a model composite interface. A 53-nm blue shift in fluorescence from the immobilized DMSCA can be followed during cure of an epoxy resin overlayer, giving this technique potential to monitor the properties of the fiber/resin interface during composite processing. Contact angle measurements on these coupling agent layers were similar in the presence or absence of the DMSCA molecule, suggesting that trace levels of the fluorescent probe did not affect the structure of the layer. The immobilized DMSCA molecule behaved similarly to the DMANS precursor in solution. Both showed longer wavelength fluorescence in more polar environments. Copyright 2000 Academic Press.

Determination of 4-demethoxy-3'-deamino-3'-aziridinyl-4'-methylsulphonyldaunorubicin+ ++ and its 13-hydroxy metabolite by direct injection of human plasma into a column-switching liquid chromatography system with mass spectrometric detection

A selective, sensitive and fully automated column-switching LC system using direct injection of human plasma followed by mass spectrometry (MS) detection was developed and validated to determine the concentrations of 4-demethoxy-3'-deamino-3'-aziridinyl-4'-methylsulphonyldaunorubicin++ + (PNU-159548) and its 13-hydroxy metabolite (PNU-169884). A 50-microl human plasma sample was directly introduced into a C4-alkyl-diol silica clean-up column separating analytes from proteins and polar endogenous compounds using water and methanol as the mobile phase. The fraction containing PNU-159548 and its metabolite was back-flushed and transferred to the analytical column. The compounds were separated using a Zorbax SB C8 column (150x4.6 mm, 5 microm) under gradient conditions with the mobile phase containing acetonitrile and 2 mM ammonium formate, pH 3.5. MS detection was by atmospheric pressure ionisation with multiple reaction monitoring in positive ion mode. Linearity was demonstrated over the calibration range of 0.051-10.291 ng/ml for PNU-159548 and 0.104-10.434 ng/ml for PNU-169884. The assay was validated with respect to accuracy, precision and analyte stability. On the basis of the validation data, the developed analytical method was found to be suitable for use in Phase I clinical studies.

Determination of PNU 157706, a new dual inhibitor of 5alpha-reductase, in rat plasma by high-performance liquid chromatography with ultraviolet detection

A HPLC procedure was developed and validated for determining nanogram per milliliter concentrations of the dual 5alpha-reductase inhibitor PNU 157706 in rat plasma. The compound was extracted from plasma with diethyl ether followed by purification using a CN cartridge. The chromatographic separation was performed with a C18 column using a water-acetonitrile-methanol mixture as eluent. UV detection at 210 nm was used for the quantification of the compound over the concentration range 5-500 ng/ml plasma. The method has a lower limit of quantification of 5 ng/ml and good precision and accuracy. This method has performed well during analysis of several toxicokinetic and pharmacokinetic studies in the rat.

Doxorubicin pharmacokinetics: the effect of abnormal liver biochemistry tests

We studied variability in doxorubicin pharmacokinetics in 24 patients with abnormal liver biochemistry tests. Blood samples were collected after the first cycle of single-agent doxorubicin given as an i.v. bolus and plasma levels were measured by high-performance liquid chromatography. The relationship between doxorubicin clearance (dose/AUC) and liver biochemistry tests (AST, bilirubin, albumin, alkaline phosphatase and indocyanine green clearance) was investigated. Patients with a raised bilirubin level had reduced doxorubicin clearance, but there was no clear relationship between the extent of this elevation and the reduction in doxorubicin clearance. Doxorubicin clearance was lower in patients with an isolated increase in AST than in those with normal liver biochemistry, but this difference was not statistically significant. Nevertheless, there was a significant correlation between reduced doxorubicin clearance and both raised serum AST levels and low indocyanine green clearance. These pharmacokinetic data suggest that current dose reductions based solely on the extent to which bilirubin is elevated may not be optimal.

Antenatally detected urinary tract abnormalities: changing incidence and management

To define the incidence of urinary tract abnormalities detected by antenatal ultrasound and assess changes in postnatal management we conducted a retrospective survey using data bases of the nephro-urology unit, obstetric ultrasound and perinatal pathology departments. The birth population (105,542) of the two Nottingham teaching hospitals between January 1984 and December 1993 was divided into two 5-year cohorts, 1984-1988 and 1989-1993. Detailed fetal scanning at 18-20 weeks gestation was introduced in 1989. During this 10-year period, 201 abnormalities of the urinary tract were noted with a 2:1 male to female ratio. The incidence of abnormalities in the first 5 years was 1 in 964 compared to 1 in 364 in the last 5 years. There was a significant increase in the number detected before 20 weeks gestation (12% in 1984-1988 compared to 62% in 1989-1993). Despite the increased incidence of abnormalities detected, the termination rate remained static between the two 5-year cohorts. Only 3 fetuses had intra-uterine intervention and 173 were live-born. Eight infants subsequently died in association with other major congenital abnormalities. The incidence of transient abnormalities (antenatal dilatation with no abnormality noted on postnatal ultrasound) increased from 6% in 1984-1988 to 18% in the 1989-1993 cohort. A more conservative approach to postnatal management is reflected by 71% of infants having operations between 1984 and 1988 compared to 35% in 1989-1993.

CONCLUSION

The advent of detailed fetal scanning at 18-20 weeks gestation has significantly increased the detection rate of urinary tract abnormalities with no significant increase in pregnancy termination rates. The need for antenatal intervention is a rare event and most problems can be managed conservatively both pre- and postnatally.

Effects of a split keyboard design and wrist rest on performance, posture, and comfort

The purpose of this study was to examine differences in experienced typists' performance, posture, and musculoskeletal pain when using a split, adjustable (SA) computer keyboard and when using a standard flat keyboard. In addition, the use of a wrist rest was examined for performance, posture, and musculoskeletal pain effects. Eighteen participants were exposed to the SA keyboard and a flat keyboard in a laboratory study of text typing for four consecutive hours on five days. The results indicated that after just 2 h of orientation and practice, the participants could perform as well on the SA keyboard as on the flat keyboard. The SA keyboard provided advantages for reduced wrist/hand pronation. There was no difference between the keyboards in the level of musculoskeletal pain reported by participants after typing. However, they reported increased pain in the back, neck, shoulders, and wrists from the beginning to the end of each of the experimental periods for both keyboards.

Intracranial aneurysms in infants and children

BACKGROUND

The diagnosis and imaging of pediatric aneurysms has changed since the advent of MR and MRA.

OBJECTIVE

To update the literature on pediatric aneurysms and better define the appropriate work-up of childhood aneurysms in 1997.

MATERIALS AND METHODS

Retrospective review of 21 children (12 boys, 9 girls) with 25 aneurysms from three institutions over a 20-year period was performed. Imaging studies were mixed and included CT (19 patients), MR (11 patients), MRA (6 patients) and angiography (18 patients).

RESULTS

Eighteen of 25 aneurysms were congenital saccular, 6 were mycotic, and 1 was post-traumatic. Of these, 44 % were in the posterior circulation. Nine aneurysms arose from distal arterial branches. Forty percent were large (between 1-2.5 cm) and 16 % were giant (> 2.5 cm). CT and MR showed hemorrhage, and frequently revealed the aneurysms as a focal mass with or without enhancement and flow void. Six children had MRA which revealed aneurysms in four patients. All patients with MRA had corresponding conventional angiography.

CONCLUSION

Characteristics of pediatric aneurysms include diversity of type, increased incidence in the posterior fossa, peripheral location, and large size. CT, MR and MRA are useful in the diagnosis with conventional angiography essential for preoperative planning.

Reconversion of bone marrow in Gaucher disease treated with enzyme therapy documented by MR

BACKGROUND

Skeletal complications are responsible for significant morbidity in Gaucher patients. Plain radiographs have been unreliable in assessing bone marrow infiltration and activity. A way to assess bone marrow improvement is needed during enzyme therapy.

OBJECTIVE

The purpose of this paper is to assess the usefulness of MR in following improvement of abnormal bone marrow in Gaucher patients on enzyme therapy.

MATERIALS AND METHODS

Three patients aged 2, 7, and 24 years underwent serial MR scans of the lower extremities before and during treatment with Alglucerase (two patients) and Imiglucerase (one patient). T1-weighted, T2-weighted, STIR and FSE T2-weighted images were utilized. Two patients were imaged after 16 months of therapy, and one patient was imaged after 6 months of therapy.

RESULTS

All patients had improvement in marrow signal consistent with partial reconversion to fatty marrow during treatment. The findings were more marked after prolonged therapy. T1-weighted images demonstrated findings most clearly.

CONCLUSION

MR consistently showed improvement in marrow signal in Gaucher patients on enzyme therapy. As smaller doses of enzyme therapy are the trend, MR can be utilized to determine if therapy is effecting a change in the bone marrow.

Transcranial Doppler, MRA, and MRI as a screening examination for cerebrovascular disease in patients with sickle cell anemia: an 8-year study

OBJECTIVE

The authors previously reported five transcranial Doppler ultrasonography (TCD) findings as significant in detecting clinical cerebrovascular disease in a 4-year study in patients with sickle cell disease. This is a follow-up to evaluate the validity of the original findings over another 4-year period during which the study population doubled. A clinical follow-up of the original asymptomatic sickle cell patients with positive TCD, MRA, and MRI was also made.

MATERIALS AND METHODS

Over an 8-year period TCD, MRI, and MRA were prospectively performed in 90 sickle cell patients who were clinically asymptomatic for stroke and in 27 sickle cell patients with clinical stroke.

RESULTS

Of the 4 out of original 46 control patients in 1992 who had positive MRA and TCD, 3 have subsequently had clinical stroke. None of the 9 original patients with positive TCD and positive MRI but negative MRA have developed stroke. All five original TCD indicators of disease were still significant (P < 0.05) for detecting clinical disease: maximum velocity in ophthalmic artery (OA) > 35 cm/s, mean velocity in middle cerebral artery (MCA) > 170 cm/s, resistive index (RI) in OA < 50, velocity in OA greater than in MCA, and velocity in posterior cerebral (PCA), vertebral, or basilar arteries greater than in MCA. An RI of < 60 in the DA was also now found to be significant [corrected]. Four additional factors were also significant: turbulence, PCA or ACA without MCA, RI < 30, and maximum velocity in MCA > 200 cm/s.

CONCLUSION

Positive MRA with a positive TCD in an asymptomatic patient in long-term follow-up suggests a trend for developing clinical stroke. A 4- to 8-year follow-up of nine patients with positive TCD, positive MRI, but not positive MRA did not show development of clinical stroke. Nine Doppler findings are significant in screening for clinically symptomatic vascular disease in sickle cell patients. It is recommended that children with sickle cell disease be screened for cerebrovascular disease with TCD. If one or two indicators of abnormality are present, MRA is recommended. If the MRA is positive, the patient may be considered for transfusion therapy or other treatment for prevention of stroke.

Snare retrieval of migrated ventriculoatrial shunt

Among the numerous complications of ventriculoatrial shunting, discontinuity and migration of a catheter fragment into the heart or pulmonary arteries is only rarely encountered. Percutaneous snare retrieval of shunt tubing from the pulmonary arteries is described in a patient presenting with signs of shunt malfunction.

Magnetic resonance angiography in trauma

Following blunt or penetrating trauma to the head and neck, a variety of traumatic vascular injuries may occur. Often the clinical presentation of a craniocervical arterial injury is delayed and neuroimaging studies are necessary to evaluate for delayed findings of intracranial infarction or hemorrhage. In this setting, magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) may allow a prompt noninvasive diagnosis of craniocervical vascular injury. MRA may be helpful in selecting those patients requiring conventional angiography and allows a noninvasive follow-up evaluation of arterial injury following institution of therapy.

Flow-flash kinetics of O2 binding to cytochrome c oxidase at elevated [O2]: observations using high pressure stopped flow for gaseous reactants

A high-pressure stopped-flow apparatus developed in our laboratories provides the capability to use dissolved gaseous reactants at elevated concentrations in solution (in equilibrium with gas pressures up to ca. 30 atm) for measurement of reaction kinetics. We have used this apparatus to follow the reaction of dioxygen with bovine cytochrome c oxidase following photolysis of the fully reduced CO ligated enzyme up to a dioxygen concentration of 16 mM. The observed rate dependence on [02] follows saturation kinetics and was fit to a limiting rate of 1.0 X 10(6) s(-1). This value is approximately the same as that for the thermal loss of CO to solution from the transient CuB bound state formed upon photolysis of the heme-CO complex. Implications for the mechanism of O2 binding and reduction by the heme-copper oxidases are discussed.

CHORTLES: a method for representing oligomeric and template-based mixtures

Screening mixtures of synthetic oligomers or fixed templates (e.g., rings) with varying substituents is increasingly the focus of drug discovery programs. CHORTLES is designed and implemented to facilitate representation, storage, and searching of oligomeric and template-based mixtures of any size. Building upon the CHUCKLES method of representing oligomers as both monomer-based sequences and all-atom structures, CHORTLES compactly represents a mixture without explicitly enumerating individual molecules. This method lends itself to a hierarchy relating mixtures to submixtures and individual compounds, as one finds when deconvoluting mixtures in drug lead discovery programs. In addition, we describe two methods of searching mixtures at the monomer level. We also present a simple pictorial representation for describing all components in a mixture, which becomes essential as the list of monomer names is expanded beyond common names (e.g., amino acids).

Altered vertebrobasilar flow in children: angiographic, MR, and MR angiographic findings

PURPOSE

To characterize the clinical, MR, MR angiographic, and conventional angiographic findings in vertebrobasilar disease in children.

METHODS

Eight children with posterior circulation ischemia and infarction had conventional spin-echo MR and MR angiography of the head and neck. Six patients had conventional angiography.

RESULTS

Six patients had alteration of vertebral or basilar artery flow void on spin-echo images. MR angiography showed all six cases of angiographically proved vertebrobasilar dissection or occlusion despite overestimating the extent of arterial abnormality in two patients. In two patients the intracranial peripheral branch cutoff shown at angiography was correctly predicted on screening MR angiography.

CONCLUSION

Posterior circulation infarction in children is usually secondary to traumatic injury to the vertebrobasilar circulation. MR and MR angiography noninvasively show vertebrobasilar flow disturbances and compare favorably with angiography in documenting dissection or occlusion of the vertebrobasilar circulation. MR angiography may obviate the need for invasive angiography in these children at diagnosis and during follow-up of anticoagulation therapy.