Interlocking finger test: a bedside screen for parietal lobe dysfunction.

This study sought to determine the utility of an interlocking finger task in screening for parietal lobe dysfunction. The ability of 69 patients to imitate a standardised set of four interlocking finger figures was compared with concurrent performance on formal neurocognitive tests. Poor interlocking finger test scores correlated most highly with standard measures of parietal lobe dysfunction. In addition, an analytical model of parietal dysfunction indicated the interlocking finger test was similar to, if not better than, standard tests of parietal lobe dysfunction. Attempts to imitate these figures should serve as a fast and simple screen of parietal lobe dysfunction.

Reduced intraepidermal nerve fiber density in HIV-associated sensory neuropathy.

OBJECTIVE: To explore the relationship between intraepidermal nerve fiber (IENF) density in HIV-associated sensory neuropathy (HIV-SN) to measurements of neuropathy severity and progression of HIV disease. BACKGROUND: SN affects 30% of individuals with AIDS, and treatment is often ineffective. Recombinant human nerve growth factor (rhNGF) has been proposed as a trophic factor for unmyelinated nerve fibers injured in HIV-SN, and a clinical trial has recently concluded. Skin biopsy with IENF density determination has emerged as a diagnostic test for patients with small-fiber sensory neuropathy. METHODS: Sixty-two of the 270 patients with HIV-SN who participated in the trial of rhNGF were included in a substudy examining epidermal nerve fibers. IENF density was compared with neuropathic pain intensity (measured with the Gracely Pain Scale), patient and physician global pain assessments, quantitative sensory testing, CD4 counts, and plasma HIV RNA levels both at baseline and at conclusion of the placebo-controlled phase. RESULTS: IENF density was inversely correlated with neuropathic pain as measured by patient (p = 0.004) and physician (p = 0.05) global pain assessments, but not using the Gracely Pain Scale. Decreased IENF density at the distal leg was associated with lower CD4 counts and higher plasma HIV RNA levels. IENF density measurements were stable over time. CONCLUSIONS: IENF loss at the distal leg is associated with increased neuropathic pain, lower CD4 counts, and higher plasma viral load in HIV-SN. The robustness of the longitudinal measurement of IENF density supports its use in future longitudinal studies and clinical trials.

Phenylketonuria presenting in adulthood as progressive spastic paraparesis with dementia.

A 57 year old woman living independently in the community presented with four years of progressive spastic paraparesis and dementia. An extensive evaluation for the usual causes of these difficulties was unrevealing, but her serum phenylalanine concentration was markedly elevated and genetic analysis demonstrated mutations in the phenylalanine hydroxylase gene consistent with classic phenylketonuria. A protein restricted diet was associated with improvement in her condition. Although untreated phenylketonuria is typically associated with severe neurological dysfunction beginning in early childhood, this case shows that disability may be delayed until adulthood.

Hemispheric asymmetry in categorical versus coordinate visuospatial processing revealed by temporary cortical deactivation.

Kosslyn (1987) proposed that the left hemisphere is better than the right hemisphere at categorical visuospatial processing while the right hemisphere is better than the left hemisphere at coordinate visuospatial processing. In 134 patients, one hemisphere (and then usually the other) was temporarily deactivated by intracarotid injection of sodium amobarbital. After a hemisphere was deactivated, a cognitive test battery was conducted, which included categorical and coordinate visuospatial tasks. Using this technique, the processing capabilities of the intact hemisphere could be determined, thus directly testing Kosslyn's hypothesis regarding hemispheric specialization. Specifically, if the left hemisphere does preferentially process categorical visuospatial relationships, then its deactivation should result in more errors during categorical tasks than right hemisphere deactivation and vise versa for the right hemisphere regarding coordinate tasks. The pattern of results obtained in both categorical and coordinate tasks was consistent with Kosslyn's hypothesis when task difficulty was sufficiently high. However, when task difficulty was low, a left hemispheric processing advantage was found for both types of tasks indicating that: (1) the left hemisphere may be better at "easy" tasks regardless of the type of task and (2) the proposed hemispheric processing asymmetry may only become apparent during sufficiently demanding task conditions. These results may explain why some investigators have failed to find a significant hemispheric processing asymmetry in visuospatial categorical and coordinate tasks.

Olfactory and taste dysfunction after bilateral middle cerebral artery stroke.

Acquired dysfunction of the sense of smell and taste is usually associated with orbitofrontal tumors or trauma and is rarely reported to have occurred after ischemic stroke. We report on a patient who noted impairment of the sense of smell and taste after a localized insular frontoparietal stroke and who also had a similar, mirror-image infarction in the other hemisphere. Injury to an area of the cortex responsible for the integration of taste and smell may have accounted for this patient's symptoms.

Both the 25-kDa and 50-kDa domains in myosin subfragment 1 are close to the reactive thiols.

The thiol-specific photoactivatable reagent benzophenone-4-iodoacetamide can be incorporated into myosin subfragment 1 (S1), accompanied by an increase of Ca2+-ATPase and the loss of K+-ATPase activities, a characteristic property of S1 when reactive sulfhydryl 1 (SH-1) is modified. After trypsin cleavage, 25-kDa, 50-kDa, and 20-kDa fragments were found upon NaDodSO4/polyacrylamide gel electrophoresis of the unphotolyzed sample, whereas only the 50-kDa fragment and a 45-kDa fragment appeared in the photolyzed sample, indicating that the NH2-terminal 25-kDa fragment was crosslinked to the COOH-terminal 20-kDa fragment via SH-1. When photolysis was carried out in the presence of Mg2+ and ATP or Mg2+ and adenosine 5-[beta, gamma-imido]triphosphate (AdoPP[NH]P), a 70-kDa band, attributable to a crosslinked (50 kDa + 20 kDa) species, was also observed. This suggests that the conformational change induced by nucleotide binding reduces the distance between the 50-kDa region and the label on SH-1. Similar results were obtained when labeling and photolysis were carried out on trypsin-nicked S1, in which the 25-kDa, 50-kDa, and 20-kDa fragments are held together noncovalently. Further, when labeling with benzophenone-4-iodoacetamide was carried out in the presence of Mg-ATP, which increases the reactivity of another thiol, presumably SH-2, both 45-kDa and 70-kDa species were formed upon photolysis in the absence of ATP, suggesting that SH-2 is close to the 50-kDa region. More of the 70-kDa species was formed, at the expense of the 45-kDa species, when photolysis was carried out in the presence of Mg-ATP. Partial heat denaturation preferentially reduced the crosslinking between the reactive thiols and the 50-kDa region.