Low cost, p-ZnO/n-Si, rectifying, nano heterojunction diode: Fabrication and electrical characterization.

A low cost, highly rectifying, nano heterojunction (p-ZnO/n-Si) diode was fabricated using solution-processed, p-type, ZnO nanoparticles and an n-type Si substrate. p-type ZnO nanoparticles were synthesized using a chemical synthesis route and characterized by XRD and a Hall effect measurement system. The device was fabricated by forming thin film of synthesized p-ZnO nanoparticles on an n-Si substrate using a dip coating technique. The device was then characterized by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The effect of UV illumination on the I-V characteristics was also explored and indicated the formation of a highly rectifying, nano heterojunction with a rectification ratio of 101 at 3 V, which increased nearly 2.5 times (232 at 3 V) under UV illumination. However, the cut-in voltage decreases from 1.5 V to 0.9 V under UV illumination. The fabricated device could be used in switches, rectifiers, clipper and clamper circuits, BJTs, MOSFETs and other electronic circuitry.

Congenital erosive and vesicular dermatosis.

An 8-year-old boy born prematurely at 26 weeks' gestation presented with a reticulate scar on the left cheek. This started as an eroded area on day 3 postpartum, followed by crusting and scarring. There were also linear scars on the left forearm, left lower back and abdomen. The clinical picture fits the entity of congenital erosive and vesicular dermatosis. This retrospective case report delineates the outcome with diagnosis only evident after an 8-year time period.

MRI in Lhermitte-Duclos disease.

Lhermitte-Duclos disease (LDD) is a disorder sometimes referred to as a dysplastic gangliocytoma of the cerebellum. This is a focally indolent growth of the cerebellar cortex in which the folia enlarge due to a profusion of dysplastic cortical neurons and a thickening of the molecular layer. Loss of Purkinje cells and thinning of medullary white matter results. The enlarged folia lose their secondary foldings and asymmetrically expand the cerebellar hemisphere. These morphologic features produce a characteristic pattern on some CTs and all MRIs, affording an opportunity for a preoperative diagnosis. MRI of a pathologic specimen suggested that the abnormal T1 and T2 signals corresponded to the atrophic folial white matter, thickened granule cell layer, and outer molecular layer. Because of inherent Hounsfield artifact in posterior fossa with CT, MRI is the imaging modality of choice, with better visualized striated pattern. The uniqueness of these imaging features obviates the need for an obligatory biopsy for asymptomatic patients and either permits more definitive planning for surgical decompression or, in restricted lesions, guides more assuredly complete excision of the cerebellar mass.

Preliminary experience using ticlopidine in clinical practice.

Although shown to be more effective than aspirin for secondary stroke prevention, the guidelines for utilizing ticlopidine in daily clinical practice are as yet undefined. We reviewed all entries into the Saint Louis University Stroke Registry for the period of January to December 1992 and identified individuals admitted with diagnosis of cerebral infarction or transient ischemic attack (TIA) and who, upon discharge, were prescribed ticlopidine. The etiologic diagnosis, event recurrence during follow-up, compliance with medication, and side effects of all these patients were documented following review of inpatient and outpatient records. A total of 32 patients, 19 (69%) with cerebral infarction and 10 (31%) with TIA were identified. The etiologic diagnoses included: 11 patients with atherothrom-boembolic events, three with lacunar strokes, seven with cardioembolic events, and 11 with stroke of uncertain etiology. None of the patients reported recurrent cerebrovascular events. Sixteen (50%) patients continued to take the drug up to their last visit, whereas 9 (28%) had it discontinued. Five patients were lost to follow-up, and two died from cardiac arrest. The reasons for drug discontinuation included high cost in two patients, allergic reactions in two, and gastrointestinal side effects in three. Two additional patients stopped taking ticlopidine on their own due to uncertain reasons. In spite of its potential usefulness, intolerance to ticlopidine and its high cost result in treatment discontinuation in a significant proportion of patients. These factors and their effect on patients' compliance must be taken into account when prescribing this medication.

Changing trends in the etiologic diagnosis of ischemic stroke.

The evaluation of victims of ischemic stroke has evolved over the last few years, primarily as a result of the introduction of innovative, sensitive, and informative diagnostic procedures. The role of the neurologist appears to have been redefined as one in which the identification of the presumptive cause and mechanism of the stroke is one of the primary responsibilities. We compared the etiologic stroke subtypes of patients entered into the Saint Louis University Stroke Registry for the period January to June, 1986 (Group A), with analogous data collected in patients entered from January to June, 1992 (Group B). Group A included 57 patients whose stroke subtype distribution was as follows: 19% due to athero-thromboembolism, 18% cardiogenic, 5% lacunar, and 4% due to other causes. In addition, 54% of patients had strokes of unknown etiology. Group B comprised 137 patients with the following etiologic distribution: 35% cardiogenic, 26% atherothrombolic, 3% lacunar, and 6% from other causes. Only 29% had strokes of unknown etiology. The apparent increase in the proportion of cardiogenic strokes may be related to wider utilization of transesophageal echocardiography. There was also a significant drop in the proportion of strokes of unknown etiology. Finally, in comparison with other stroke registries, our data suggest that many small strokes may also result from cardiogenic embolism. These apparent changes in the proportion of stroke subtypes should be considered when patients are being evaluated for risk stratification.

Delay between emergency room arrival and stroke consultation.

We reviewed retrospectively the charts of all stroke patients admitted through our emergency room (ER) during the first halves of 1986 (Group A) and 1992 (Group B). Specifically, the time elapsed between ER arrival and the request for consultation by neurology or neurosurgery was subjected to comparison by analysis of variance. In Group A, the time elapsed from arrival to consultation request varied between 1 and 100 min (mean, 32.5). In Group B, the same period ranged from 2 to 285 min (mean, 84). The difference in mean elapsed time between the two groups was statistically significant (<0.0001). In Group A, patients with hemorrhagic events had significantly shorter delay between arrival and consultation (p = 0.026). This was not the case in Group B. Stroke type did not influence the time to consultation in Group A (p = 0.18) orGroupB (p = 0.60). The results show that neurologic and neurosurgical consultations of stroke patients in the ER are delayed more now than in the past. This finding may have a significant impact on acute stroke intervention trials and underscores the need for active collaboration between stroke specialists and emergency physicians.

The management concerns of hospital pharmacy directors.

In conclusion, this research shows that pharmacy directors in Chicago hospitals face problems on several fronts, though not all are of equal importance. Of particular interest is that, contrary to theoretical expectations, the directors do not consider problems involving relationships with other organizational actors to be extremely important. This issue (as well as others raised here) needs to be investigated in broader and deeper terms. The issue carries important implications, especially in a health care environment that should encourage innovation and negotiation among the professional members of provider organizations.

Acute myelopathy following intravenous heroin: a case report.

A 43-year-old woman developed acute paraplegia and a Korsakoff syndrome following intravenous administration of heroin. Thirteen previously reported cases are similar to the one presented here. Based on those similarities, we conclude that these myelopathies are probably due to spinal cord infarction resulting from systemic hypoxemia and hypotension.

Transcranial Doppler in reversible migrainous vasospasm causing cerebellar infarction: report of a case.

A young woman with a history of classic migraine suffered a large cerebellar infarction. Comprehensive evaluation did not disclose any potential causes for the stroke and she had no other risk factors. Transcranial Doppler (TCD) was useful in identifying vasospasm of the vertebral arteries. Following treatment with propranolol, angiography and repeat TCD revealed resolution of the vasospastic disorder. TCD is a useful noninvasive tool in detecting vasospasm associated with ischemic lesions in certain patients with migraine.

Noninvasive evaluation of ischemic stroke with SPECT.

Technetium Tc 99m DTPA single photon emission computerized tomography (SPECT) brain scans of 20 patients with acute ischemic stroke were reviewed retrospectively and compared with clinical and radiologic (CT) data. Fourteen of the patients had abnormal SPECT studies. The abnormal findings were demonstrated by static views in eight patients, by the flow study in one patient, and by both sets of images in the other five patients. All abnormalities correlated with the clinical syndrome of presentation, and only two of the patients had no corresponding lesions on CT. Of the six patients with normal SPECT scans, two had abnormal CT studies, and in the other four, no lesions were shown at all. The ability of 99mTc DTPA SPECT to display cerebral infarctions appears to be, at best, comparable to that of CT. SPECT also provides qualitative information regarding flow dynamics in the affected hemisphere of some patients (6/20 in our review). This, we believe, represents the objective demonstration of the preexisting insufficient collateral flow in the hemisphere at risk for ischemic stroke.

Mutagenicity testing of some medicinal herbs.

Extracts of four brands of a Pakistani local medicine called naswar and six indigenous herbs commonly used as medicine in children were tested for their ability to induce mutations to prototrophy in Salmonella typhimurium tester strains TA98, TA100, TA1535, and TA1537. Petroleum ether extracts of one brand of naswar, namely green naswar of Peshawar, exhibited mutagenicity in all of the four tester strains. Organic extracts of three herbs, Saussurea lappa, Swertia chiraita, and Skimmia laureola, exhibited mutagenic activity in tester strain TA98. Green naswar of Bannu, grey naswar, red naswar, and the remaining three herbs, namely, Acorous calamus, Azadarachta indica, and Zanthozylum alatum, exhibited no mutagenic activity under the present experimental conditions. The abilities of green naswar of Peshawar and Saussurea lappa to induce mutations was shown to be related to the presence of cyclic aromatic compounds with molecular formulas C34 H44 O9 and C15 H18 O2, respectively. The experimental data are discussed as they relate to the potential hazards of such naturally occurring compounds and to synthetic compounds in excessive and uncontrolled use by the general public in villages in Pakistan.