Ominous Causes of Headache

PURPOSE OF REVIEW

While primary headaches like migraines or cluster headaches are prevalent and often debilitating, it's the secondary headaches-those resulting from underlying pathologies-that can be particularly ominous. This article delves into the sinister causes of headaches, underscoring the importance of a meticulous clinical approach, especially when presented with red flags.

RECENT FINDINGS

Headaches, one of the most common complaints in clinical practice, span a spectrum from benign tension-type episodes to harbingers of life-threatening conditions. For the seasoned physician, differentiating between these extremes is paramount. Headache etiologies covered in this article will include subarachnoid hemorrhage (SAH), cervical artery dissection, cerebral venous thrombosis, meningitis, obstructive hydrocephalus, and brain tumor.

14N-Kernresonanzmessungen an Isonitril- und Nitril-Metallkomplexen

14N chemical shifts are reported for nitriles, isocyanides and complexes with nitriles, isocyanides, and isohydrocyanic acid.

The correlation of the 14N coordination shifts with the metal-ligand back bonding as known from IR-investigations is discussed.

While pi bonding seems to be insignificant in isocyanide complexes with metal cations, such as Fe2⊕, 14N-NMR measurements suggest an increase of pi bond order on going from isocyanide carbonyl complexes to compounds in which isonitriles are the only ligands bound to zerovalent metals

Atomic emission detection for gas chromatographic analysis of nitrogen-containing herbicides in water

A gas chromatography-atomic emission detection (GC-AED) system was used to analyze nitrogen-containing herbicides. Two methods of sample preparation were used to demonstrate the system's applicability. Method 1 was U.S. Environmental Protection Agency (EPA) Method 507. Method 2 was a modification of EPA Method 507 using larger sample volumes and smaller extract volumes to yield compound detection levels 30 times lower than detection levels from method 1. Analysis of replicate reagent water spikes with method 1 gave analyte recoveries ranging from 82 to 107%, with standard deviations of recovery of not more than 6.7%. Method 2 gave recoveries ranging from 50 to 112%, with a standard deviation of recovery of not more than 33%. A loss in recovery and precision with method 2 compared with method 1 was attributed to loss of more volatile analytes during extract concentration. Selectivity was demonstrated with solvent spiked with fuel oil and atrazine. Response factors generated with the GC-AED system showed compound-independent elemental linearity for analytes. Relative standard deviations of not more than 5.34% were obtained for 3 elements tested: nitrogen, sulphur, and chlorine. An elemental calibration mixture was prepared to validate traditional methods of quantitation. Samples were analyzed for nitrogen-containing herbicides, which were quantitated with both an analyte calibration and an elemental calibration, and results were compared.

Evidence for a laminar organization of basal forebrain afferents to the visual cortex

The present study shows that restriction of HRP injections to layer I within the visual cortex results in negligible retrograde labeling within the nuclei of the basal forebrain. In contrast, when the injections of either HRP or WGA-HRP are restricted to the granular and infragranular layers of visual cortex, extensive retrograde labeling occurs within the basal forebrain. Based upon these findings, we argue that the projection from the basal nucleus terminates preferentially within the deep layers of the visual cortex, and thus contributes minimally to the supragranular layers, including layer I.