Reservoir Sedimentation and Upstream Sediment Sources: Perspectives and Future Research Needs on Streambank and Gully Erosion.

The future reliance on water supply and flood control reservoirs across the globe will continue to expand, especially under a variable climate. As the inventory of new potential dam sites is shrinking, construction of additional reservoirs is less likely compared to simultaneous flow and sediment management in existing reservoirs. One aspect of this sediment management is related to the control of upstream sediment sources. However, key research questions remain regarding upstream sediment loading rates. Highlighted in this article are research needs relative to measuring and predicting sediment transport rates and loading due to streambank and gully erosion within a watershed. For example, additional instream sediment transport and reservoir sedimentation rate measurements are needed across a range of watershed conditions, reservoir sizes, and geographical locations. More research is needed to understand the intricate linkage between upland practices and instream response. A need still exists to clarify the benefit of restoration or stabilization of a small reach within a channel system or maturing gully on total watershed sediment load. We need to better understand the intricate interactions between hydrological and erosion processes to improve prediction, location, and timing of streambank erosion and failure and gully formation. Also, improved process-based measurement and prediction techniques are needed that balance data requirements regarding cohesive soil erodibility and stability as compared to simpler topographic indices for gullies or stream classification systems. Such techniques will allow the research community to address the benefit of various conservation and/or stabilization practices at targeted locations within watersheds.

Germination tests for assessing biochar quality.

Definition, analysis, and certification of biochar quality are crucial to the agronomic acceptance of biochar. While most biochars have a positive impact on plant growth, some may have adverse effects due to the presence of phytotoxic compounds. Conversely, some biochars may have the ability to adsorb and neutralize natural phytotoxic compounds found in soil. We evaluated the effects of biochars on seedling growth and absorption of allelochemicals present in corn ( L.) residues. Corn seeds were germinated in aqueous extracts of six biochars produced from varied feedstocks, thermochemical processes, and temperatures. Percent germination and shoot and radicle lengths were evaluated at the end of the germination period. Extracts from the six biochars had no effect on percent germination; however, extracts from three biochars produced at high conversion temperatures significantly inhibited shoot growth by an average of 16% relative to deionized (DI) water. Polycyclic aromatic hydrocarbons detected in the aqueous extracts are believed to be at least partly responsible for the reduction in seedling growth. Repeated leaching of biochars before extract preparation eliminated the negative effects on seedling growth. Biochars differ significantly in their capacity to adsorb allelochemicals present in corn residues. Germination of corn seeds in extracts of corn residue showed 94% suppression of radicle growth compared to those exposed to DI water; however, incubation of corn residue extracts with leached biochar for 24 h before initiating the germination test increased radicle length 6 to 12 times compared to the corn residue extract treatments. Germination tests appear to be a reliable procedure to differentiate between effects of different types of biochar on corn seedling growth.

Impact of new AABB guidelines on hepatitis B and C testing among Saudi blood donors.

This study aims to compare the advantages and disadvantages of implementing the new American Association of Blood Banks (AABB) guidelines for hepatitis B and C against its old criteria for screening blood donors. Between July 1995 and December 2002, 63,368 consecutive blood donors were screening for hepatitis B and C according to the new guidelines. Cost and prevalence were analysed and compared with those found using the old AABB guidelines prior to July 1995. The overall percentage rate of deferred donors showed a significantly decrease to 19.3% in 2002, compared to 58.4% before July 1995 (P < 0.001). The new prevalence of hepatitis B and C among Saudi blood donors was found to be 1.7% and 0.6%, respectively, compared to 4% and 1.4%, respectively, under the old AABB guidelines. This resulted in a significant increase in the number and yield of blood units, and a decrease in the prevalence of hepatitis B and C was observed among screened donors. Using the new AABB guidelines, the estimated direct cost of donor screening for hepatitis B and C decreased significantly from 42.8 dollars per donor to 29.2 dollars per donor (P<0.001).

Mutations that disrupt the carboxyl-terminus of gamma-sarcoglycan cause muscular dystrophy.

Recently, mutations in the genes encoding several of the dystrophin-associated proteins have been identified that produce phenotypes ranging from severe Duchenne-like autosomal recessive muscular dystrophy to the milder limb-girdle muscular dystrophies (LGMDs). LGMD type 2C is generally associated with a more severe clinical course and is prevalent in northern Africa. A previous study identified a single base pair deletion in the gene encoding the dystrophin-associated protein gamma-sarcoglycan in a number of Tunisian muscular dystrophy patients. To investigate whether gamma-sarcoglycan gene mutations cause autosomal recessive muscular dystrophy in other populations, we studied 50 muscular dystrophy patients from the United States and Italy. The muscle biopsies from these 50 patients showed no abnormality of dystrophin but did show diminished immunostaining for the dystrophin-associated protein alpha-sarcoglycan. Four patients with a severe muscular dystrophy phenotype were identified with homozygous, frameshifting mutations in gamma-sarcoglycan. Two of the four have microdeletions that disrupt the distal carboxyl-terminus of gamma-sarcoglycan yet result in a complete absence of gamma-and beta-sarcoglycan suggesting the importance of this region for stability of the sarcoglycan complex. This region of gamma-sarcoglycan, like beta-sarcoglycan, has a number of cysteine residues similar to those in epidermal growth factor cysteine-rich regions.

A 10-year experience with postpump chorea.

Postpump chorea (PPC) is the development of choreoathetoid movements within 2 weeks following cardiopulmonary bypass. Over a 10-year period, 668 children underwent open cardiac surgery, of whom 8 (1.2%) developed PPC. Age at surgery ranged from 8 to 34 months. The onset of chorea was 3 to 12 days following surgery. Computed tomography and magnetic resonance imaging showed atrophy but no focal lesions. Cerebral positron emission tomography using [18F]fluorodeoxyglucose in a patient following 12 months of chorea showed patchy areas of decreased glucose metabolism. None of the patients were developmentally normal 22 to 130 months following surgery. Three patients have had transient and 5 have persistent chorea. Neurological deficits ranged from a mild learning disability to progressive hypotonia and obtundation ending in death. One of 4 patients who received haloperidol had a decrease in the severity of chorea. We compared PPC patients with 39 randomly selected controls. During surgery, affected patients spent significantly more time on pump and at temperatures under 36 degrees C, were cooled to lower temperatures than controls, and were more likely to have had a circulatory arrest. One patient developed chorea without a history of circulatory arrest. We conclude that (1) there is a strong association between PPC, deep hypothermia, and circulatory arrest, (2) absence of characteristic macroscopic changes suggests a biochemical or microembolic etiology in some cases, (3) chorea is frequently associated with developmental delay, and (4) the prognosis for complete resolution of chorea is guarded.

Dissociation of cerebral blood flow, glucose metabolism, and electrical activity in pediatric brain death. Case report.

A 2-month-old infant demonstrated clinical brain death 48 hours after suffering a closed head injury accompanied by cardiac arrest. Two nuclear cerebral blood flow (CBF) studies demonstrated normal perfusion. On the 11th day following injury, cerebral electrical activity ceased and a normal glucose metabolic gradient between gray and white matter was documented on positron emission tomography. Autopsy revealed widespread necrosis with mononuclear cell infiltrates throughout all cerebral cortical layers. Nine children have previously been described with clinical brain death, electrocerebral silence, and evidence of CBF by radionuclide scan. The dissociation between cerebral electrical activity and blood flow may be explained by an increase in cranial volume allowed by the expansile neonatal skull, preventing both intracranial hypertension and a reduction in perfusion pressure. The persistence of glucose metabolism may be associated with the presence of inflammatory microglial cells in the ischemic cortex. The authors conclude that persistence of CBF and glucose metabolism in brain-dead children may not indicate neuronal survival. If repeated neurological examinations with or without electroencephalography support the diagnosis of brain death, the presence of CBF and glucose metabolism should not alter this conclusion.

Vasovagal syncope: diagnostic role of head-up tilt test in patients with positive ocular compression test.

We investigated the relative merits of the ocular compression test and the head-up tilt test to aid differentiation of syncope and seizures in young patients. Sixteen patients (10 males and 6 females) with a mean age of 14 +/- 4.7 (SD) years (range 7-22 years) underwent graded head-up tilt (15 degrees, 30 degrees, and 45 degrees for 2 minutes each, then 60 degrees for 20 minutes) following positive ocular compression testing defined as precipitation of asystole for at least 3 seconds (mean 5 seconds +/- 2 seconds, range 3-12 seconds). Each patient presented with recurrent unexplained loss of consciousness (mean number of episodes 30 +/- 45, mean duration of illness 52 +/- 40 months), and seven patients were receiving anticonvulsant medications, three of these had normal EEGs. Eleven patients (69%) developed vasovagal syncope during head-up tilt, reproducing their clinical episodes (systolic blood pressure decreased from 105 +/- 10 mmHg to 84 +/- 13 mmHg, diastolic blood pressure from 75 +/- 9 to 22 +/- 25 mmHg, and heart rate from 89 +/- 13 beats/min to 37 +/- 20 beats/min). Asystole occurred in two patients during vasovagal syncope lasting 11 seconds in one and 16 seconds in the other, and, it was associated with myoclonic movements in both (convulsive syncope). Based on these findings, and given the perceived potential hazards of the ocular compression test, the head-up tilt test may be a safer procedure that adds useful information to the diagnostic evaluation of these patients.

Psychogenic seizures in children and adolescents: outcome after diagnosis by ictal video and electroencephalographic recording.

Psychogenic seizures in 21 nonepileptic children and adolescents, aged 8 to 18 (mean 14.5) years, were recorded by means of video recording and electroencephalography. The episodes included thrashing movements, limb jerking, or staring, with unresponsiveness. Ictal and interictal electroencephalograms showed no abnormalities after antiepileptic medication was discontinued. Fifteen patients had psychogenic seizures spontaneously during recording, and six had seizures in response to suggestion and intravenous saline injection. After the video-electroencephalographic evaluation, patients and families were told that the episodes were emotional in origin. All patients but 1 agreed to remain without antiepileptic medication, and 16 patients (76%) agreed to begin psychiatric treatment. At 6 to 66 (mean 30) months' follow-up, 14 of 18 (78%) were free of episodes. These data indicate that the majority of young patients with psychogenic seizures have a good outcome. A firm diagnosis is critical so that the episodes can be classified and emphasized as medically not worrisome, permitting a shift away from antiepileptic medication and toward psychiatric treatment.

Fiber-type specific caffeine sensitivities in normal human skinned muscle fibers.

Caffeine sensitivity was studied in chemically skinned muscle fibers from vastus lateralis muscle obtained by biopsy during reconstructive knee surgery from 15 otherwise healthy young individuals. Muscle fiber type was determined by contracture occurring in strontium (slow-oxidative, type I fiber) or calcium (both type I and type II, fast glycolytic fiber) solutions and in several fibers after contracture testing by ATPase enzyme histochemistry. Caffeine sensitivity (mean +/- SD), defined as the threshold concentration inducing more than 10% of the maximal tension obtained with a calcium 3 x 10(-5) mM solution was 2.7 +/- 1.3 mM in 37 type I fibers, whereas it was 6.9 +/- 2.4 mM in 61 type II fibers. A paired t test showed a significantly increased sensitivity to caffeine in type I fibers (P less than 0.001) in 13 individuals in whom the two fiber types were identified. The mean (+/- SD) difference between type I and type II fibers was 4.1 +/- 1.9 mM. Type I fibers contracted with greater tension in response to the increasing concentration of caffeine than did type II fibers (P less than 0.05). These skinned fiber studies showed significantly different caffeine sensitivities between human type I and type II muscle fibers, as previously shown in animal muscles. The findings that human type I muscle fibers have higher caffeine sensitivity than type II muscle fibers should be helpful for the interpretation of the in vitro contracture test done in muscle strips containing type I and type II fibers in varying proportions.

Response of CSF IgG to steroids in an 18-month-old with chronic inflammatory polyradiculoneuropathy.

During recovery from a upper respiratory infection, an acquired chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) developed in a previously healthy 18-month-old girl. The CIDP followed a monophasic course and left her severely quadriparetic. One year after her neurologic deficit had stabilized, the cerebrospinal fluid (CSF) IgG synthesis rate was markedly elevated, and oligoclonal bands were identified in her CSF, suggesting ongoing inflammation. Her electromyogram (EMG) and nerve biopsy were consistent with a severe acquired segmental demyelinating polyradiculoneuropathy. A course of corticosteroid therapy resulted in dramatic, sustained, clinical and electromyographic improvement, normalization of CSF IgG synthesis rate, and disappearance of the oligoclonal bands. We are not aware of any previous reports that correlate serial measurements of CSF IgG synthesis rate and oligoclonal bands with clinical and electromyographic responses to corticosteroids in a child with acquired CIDP. We suggest that these CSF parameters are potentially useful in demonstrating active inflammation in cases of acquired CIDP even after clinical stabilization of neurologic deficits, predicting response to therapy, and monitoring resolution of the pathologic process.

Dandy-Walker cyst upward herniation: the role of magnetic resonance imaging and double shunts.

Upward transtentorial herniation of a Dandy-Walker cyst is a potentially fatal complication, particularly after solitary shunting of the lateral ventricle for associated hydrocephalus. Two patients with upward transtentorial herniation of their Dandy-Walker cysts are presented to illustrate the diagnostic value of magnetic resonance (MR) imaging with the demonstration of unique 'keyhole' and 'snail' signs on the axial and sagittal MR images, respectively. In both patients, double and simultaneous shunting en-Y of a lateral ventricle and the posterior fossa cyst resulted in the resolution of the herniation syndrome.

Hypoglycemia in a child with congenital muscular dystrophy.

Since skeletal muscle is an important source of precursor for gluconeogenesis, it would not be surprising if carbohydrate metabolism was altered in some muscle disorders. We report a 7-10/12-year-old white male with congenital muscular dystrophy whose recurrent episodes of vomiting and dehydration were due to fasting hypoglycemia. He was found to have a blood glucose of 21 mg/dl with an episode of vomiting and dehydration. Diagnostic fasting replicated the symptoms and hypoglycemia. Associated laboratory findings included hypoalaninemia, ketonemia, and acidosis. With use of frequent feedings, there were no further episodes over 1-9/12 years of observation. To our knowledge this is the first report of hypoglycemia complicating muscular dystrophy. However, hypoglycemia may not be diagnosed because of the nonspecific nature of the symptoms. Hypoglycemia should be considered when children with reduced muscle mass develop otherwise unexplained vomiting.

Association of heterotopic gray matter with seizures: MR imaging. Work in progress.

Heterotopic gray matter, which previously had been associated with severe congenital malformations of the brain and developmental delay, was found without these associated conditions. The authors found ten cases of heterotopic gray matter on magnetic resonance (MR) images. The lesions had a signal intensity that was isointense compared with that of gray matter on T1, spin-density, and T2-weighted images. Nine of the ten cases were associated with a seizure disorder. The tenth case, discovered during a workup for metastatic lung disease, was confirmed with pathologic studies. Heterotopic gray matter is the presence of cortical neurons in an abnormal location, which may be periventricular (nodular) or within the white matter (laminar). A knowledge of heterotopic gray matter and its association with seizures may prevent the misinterpretation of findings on MR images.

Subdural electrodes in the evaluation for epilepsy surgery in children and adults.

To evaluate the utility and safety of chronic extraoperative subdural EEG and functional localization studies in children compared to adults, we studied 61 patients each of whom had similar evaluations for epilepsy surgery, regardless of age. The 23 children and adolescents (3 to 18 years old) and the 38 adults (20 to 41 years old) each had several days and nights of extraoperative EEG from scalp and chronically-implanted subdural electrodes, and the same percentage of children and adults also had functional localization studies including cortical electrical stimulation. The methods and results of these studies and of the subsequent resections did not differ between the two groups, and they both had similar rate of complications and similar incidence of good outcome. The subdural technique was as effective and well-tolerated in children and adolescents as in adults. Other invasive EEG techniques have not yet been systematically compared between children and adults, but the subdural technique, at least, appears to be suitable for patients over a wide age range.

Complex partial seizures of childhood onset. A five-year follow-up study.

Few detailed studies have examined the long-term outcome of complex partial seizures (CPS) in children and adolescents. Previous studies have selected patients on clinical criteria only or have included those with benign focal epileptiform discharges of childhood, nonepileptiform sharp transients, and generalized epileptiform discharges. We have followed up 29 patients with clinically and electroencephalographically defined CPS of childhood onset for five years or more. Twelve patients are seizure free, eight of them after having epilepsy surgery. Of the remaining, eight patients have intractable seizures. Only one patient was able to discontinue anticonvulsant therapy after epilepsy surgery. No patient had spontaneous remission of seizures without anticonvulsant medications. School difficulties, behavior problems, and unemployment were seen in half the group. We believe CPS in this age group are difficult to control and need aggressive management. In selected patients, epilepsy surgery offers a good chance of seizure control and improvement of educational, social, and vocational potential.

Clinical outcome after complete or partial cortical resection for intractable epilepsy.

This is the first epilepsy surgery series to analyze the definition of "completeness" of resection, based solely on results of chronic scalp and subdural EEG recording. When patients had complete removal of all cortical areas with ictal and interictal epileptiform discharges, the clinical outcome was usually good. When areas with epileptiform discharges were left behind, good outcome was significantly less frequent. This correlation between complete resection and good outcome was independent of the presence or absence of CT-detected structural lesions or sharp waves on post-resection electrocorticography. These results support completeness of resection, defined by prolonged extraoperative EEG, as an important factor in seizure surgery.

The natural history of Tourette syndrome: a follow-up study.

Initial reports described Tourette syndrome as a lifelong disorder. Since then, others have noted that some patients experience remissions during late adolescence. To examine this issue, we sent questionnaires to 99 patients with Tourette syndrome who were 15 to 25 years old. The majority of the 58 respondents indicated that they had fewer tics as they reached late adolescence or young adulthood. Although most reported associated behavior or learning problems, the majority felt they were coping well. The long-term outcome in many patients with Tourette syndrome may be more optimistic than previously reported.