Molecular biology. Cancer fighter's modus operandi revealed

Researchers have deciphered how a promising cancer drug acts like a smart bomb, homing in on only a very narrow range of its potential targets in the cell. The compound, known as STI-571, has shown remarkable success in early clinical trials on patients with chronic myelogenous leukemia. Now, in work reported on page 1938, scientists reveal just how the compound works--information that could aid in the design of similar cancer therapies.

Medicine. DNA arrays reveal cancer in its many forms

The use of microarrays--slides or chips systematically dotted with DNA from thousands of genes--to determine gene expression patterns is providing a wealth of new information that should aid in cancer diagnosis and ultimately in therapy. In the past several months, researchers in several labs have used microarray technology to identify specific subtypes of a variety of cancers, including leukemias and lymphomas, the dangerous skin cancer melanoma, and breast cancer. In some cases, they can determine which cancers are likely to respond to current therapies and which aren't. In addition, the studies are giving researchers a fix on which genes are important for the development, maintenance, and spread of the various cancers, and are thus possible drug targets.

Tumor angiogenesis. Gene expression patterns identified

Researchers have obtained the most detailed sketch yet of how cancerous tumors secure the blood supplies that nourish their growth. On page 1197, a team reports the results of a large-scale comparison of the genes expressed in the blood vessels of human colon cancers and of normal colon tissue. They've found that the gene expression patterns of the two types of vasculature are distinctly different. The findings could help researchers develop new anticancer drugs that work by homing in on the protein products of genes that are overexpressed in tumor vessels, thus shutting off the growth of blood vessels the tumor needs to survive.

Alzheimer's congress. Drug shows promise for advanced disease

Although the b-amyloid vaccine now being explored as a potential Alzheimer's therapy attracted the bulk of the attention at the World Alzheimer Congress 2000 (see previous story), another, more conventional, drug is showing promise in clinical trials. A neuropsychiatrist reported at the "hot topics" session of the congress that the drug memantine, which has been used in Germany for 10 years to treat dementias, significantly slowed the progression of Alzheimer's symptoms in patients with moderately severe disease.

Masseter reflex latencies and amplitudes are not influenced by supratentorial and cerebellar lesions

The aim of this study was to investigate possible influences of suprasegmental lesions on the masseter reflex. The masseter reflex was elicited in 54 patients with supratentorial (37 patients) or cerebellar (17 patients) lesions 3-11 days after the acute onset of clinical disease. Patients showing lesions within the pons and midbrain on thin-slice magnetic resonance imaging were excluded from evaluation. The testing procedure included an additional facilitating maneuver (opening and closing the jaw before tapping). Masseter reflex latencies, interside differences, and amplitudes were within the normal range in all patients. Latencies were not different with and without the facilitating maneuver. Amplitudes were significantly higher with the maneuver, but interside differences of amplitudes were unchanged. Masseter reflex abnormality can be taken as a reliable measure of direct involvement of the reflex arc.

Blink reflex R2 changes and localisation of lesions in the lower brainstem (Wallenberg's syndrome): an electrophysiological and MRI study

OBJECTIVES

Pathways of late blink reflexes are detected by high resolution MRI. Electronically matched stroke lesions superimposed to an anatomical atlas show the suspected course.

METHODS

Fifteen patients with infarction of the lower brainstem, MRI lesions and electrically elicited blink reflexes were examined. The involved structures in patients with R2 and R2c blink reflex changes were identified by biplane high resolution MRI with individual slices matched to an anatomical atlas at 10 different levels using digital postprocessing methods.

RESULTS

The blink reflexes were normal in five of 15 patients (33%) and showed loss or delay of R2 and R2c to stimulation ipsilaterally to lesion (R2-i and R2c-i) in eight (53%). Loss or delay of R2-i/R2c-i was seen in lesions covering the entire trigeminal spinal tract and nucleus (TSTN) at at least one level. These infarctions were located more dorsally within the medulla. Patients with normal blink reflexes showed lesions sparing or involving the TSTN only partially. They more often had incomplete Wallenberg's syndromes and MRI lesions were located more ventrally.

CONCLUSIONS

Using digital postprocessing MRI methods it was possible to identify central pathways of late blink reflex in patients with Wallenberg's syndrome. This method is suggested as a new approach to identify incompletely understood functional structures of the brainstem.

Ipsilateral facial weakness in upper medullary infarction-supranuclear or infranuclear origin?

We describe two patients with upper medullary infarctions showing ipsilateral facial weakness and relative sparing of the upper facial muscles. Electrophysiological follow-up using transcranial magnetic stimulation of the motor cortex in combination with stimulation of the peripheral facial nerve disclosed a supranuclear (corticofacial) tract lesion in one patient and a partial nuclear/infranuclear intra-axial facial nerve lesion in another.

Leptomeningeal carcinomatosis and cranial nerve palsy as presenting symptoms of a clinically inapparent gallbladder carcinoma

We present an occult metastatic signet-ring cell gallbladder carcinoma in a 78-year-old woman, who complained of recurrent headaches, dysarthria, and paresis of the tongue. Cranial imaging showed contrast enhancement of the basal leptomeninges, and the cerebrospinal fluid displayed clusters of adenocarcinoma cells proposed as leptomeningeal carcinomatosis of the breast, lung or gut. However, postmortem examination revealed the gallbladder as the site of the primary carcinoma with focal signet-ring cell differentiation. In patients with progressive neurologic deterioration due to leptomeningeal carcinomatosis, adenocarcinomas from the gastrointestinal and hepatic systems should be considered. It is likely that signet-ring cell carcinomas display an increased affinity to leptomeningeal spread.

Who cares? Grandparent/grandchild households

Based on data from the 1988 National Health Interview Survey and the Child Health Supplement, we compared the health of women 40 years of age and over living four family structures: alone, solely raising grandchildren, married with spouse only, and married with spouse and grandchildren. We found that, in general, women solely raising grandchildren have poorer health compared to women of a similar age living in other family structures and considerably worse health than women with spouses raising grandchildren.

Abolished laser-evoked potentials and normal blink reflex in midlateral medullary infarction

We investigated two patients presenting with the rare finding of almost isolated hemianalgesia with a sensory level on the contralateral side sparing the face. Clinical findings, electrophysiological studies (absent laser-evoked pain-related somatosensory potentials, normal electrically evoked somatosensory potentials, magnetically evoked potentials, and blink reflexes), and magnetic resonance imaging showed the ventrolateral medullar tegmentum containing the spinothalamic tract to be affected by lacunar infarction. The blink reflex R2 component was unimpaired in both patients.

Long-term effects of transcranial magnetic stimulation on hippocampal reactivity to afferent stimulation

Transcranial magnetic stimulation (TMS) has become a promising treatment of affective disorders in humans, yet the neuronal basis of its long-lasting effects in the brain is still unknown. We studied acute and lasting effects of TMS on reactivity of the rat hippocampus to stimulation of the perforant path. Application of TMS to the brain of the anesthetized rat caused a dose-dependent transient increase in population spike (PS) response of the dentate gyrus to perforant path stimulation. In addition, TMS caused a marked decrease in inhibition and an increase in paired-pulse potentiation of reactivity to stimulation of the perforant path. Also, TMS suppressed the ability of fenfluramine (FFA), a serotonin releaser, to potentiate PS response to perforant path stimulation. Chronic TMS did not affect single population spikes but caused an increase in paired-pulse potentiation, which was still evident 3 weeks after the last of seven daily TMS treatments. After chronic TMS, FFA was ineffective in enhancing reactivity to perforant path stimulation, probably because it lost the ability to release serotonin. In addition, the beta adrenergic receptor agonist isoproterenol, which caused an increase in PS in the control rats, failed to do so in the TMS-treated rats. These results indicate that TMS produces a long-term reduction in efficacy of central modulatory systems.

Isolated voluntary facial paresis due to pontine ischemia

We describe a patient with isolated voluntary facial paresis due to a unilateral lacunar lesion in the contralateral mediodorsal middle base of the pons. Transcranial magnetic stimulation confirmed the involvement of supranuclear corticofacial tract fibers and sparing of the corticolingual and corticospinal connections. This observation demonstrates that the fibers conveying voluntary orofacial activation descend mediodorsally at the level of the middle pons and that the fibers conveying emotional activation may be assumed to converge below this level.

A novel SP-1 site in the human interleukin-1 beta promoter confers preferential transcriptional activity in keratinocytes

To investigate the mechanisms of transcriptional activation of interleukin-1beta (IL-1beta) in non-monocytic cells, we constructed a series of reporter plasmids with the bacterial chloramphenicol acetyltransferase gene linked to various parts of the human IL-1beta promoter and performed transient transfection experiments. We identified a promoter segment that activates transcription most efficiently in keratinocytes. Electrophoretic mobility shift assays (EMSA) with a 43-mer oligonucleotide derived from the functionally identified cis-acting element revealed specific complexes. By competition analysis with transcription factor consensus sequence oligonucleotides and by immunosupershift, transcription factor SP-1 or a closely related protein was shown to bind to this regulatory element. The closest match to the known SP-1 consensus sequence within the respective region is a TCCCCTCCCCT motif. Mutation of this motif almost completely, and specifically, abolished the binding of two low-mobility complexes and led to a 95% decrease of constitutive transcriptional activation of a reporter construct IL-1beta (-170/+108). Likewise, activation of this reporter construct by tumor necrosis factor-alpha depended on the SP-1 site. These observations suggest that a so-far-unrecognized SP-1 site in the human IL-1beta promoter may participate in the transcriptional regulation of this gene in keratinocytes.