A cluster classification for histologic diagnoses of CNS tumors in an epidemiologic study

Calcium-sensing receptor in cancer: good cop or bad cop?

The extracellular calcium-sensing receptor (CaR) is a versatile 'sensor' for di- and polycationic molecules in the body. CaR plays a key role in the defense against hypercalcemia by "sensing" extracellular calcium levels in the parathyroid and kidney, the key organs maintaining systemic calcium homeostasis. Although mutation of CaR gene has so far not been associated with any malignancy, aberrant functions of CaR have implications in malignant progression. One situation is loss of CaR expression, resulting in loss of growth suppressing effects of elevated extracellular Ca(2+) by CaR, reported in parathyroid adenoma and in colon carcinoma. Another situation is activation of CaR, resulting in increased production of parathyroid hormone-related peptide (PTHrP), a primary causal factor in hypercalcemia of malignancy and a contributor to metastatic processes involving bone. CaR signaling and effects have been studied in several cancers including ovarian cancers, gastrinomas, and gliomas in addition to comparatively detailed studies in breast, prostate, and colon cancers. Studies on H-500 rat Leydig cells, a xenotransplantable model of humoral hypercalcemia of malignancy has shed much light on the mechanisms of CaR-induced cancer cell growth and survival. Pharmacological agonists and antagonists of CaR hold therapeutic promise depending on whether activation of CaR is required such as in case of colon cancer or inactivating the receptor is required as in the case of breast- and prostate tumors.

Extracellular calcium-sensing receptor induces cellular proliferation and activation of a nonselective cation channel in U373 human astrocytoma cells

A receptor for extracellular calcium ions (Ca2+o), cloned from parathyroid gland, serves a critical function in Ca2+o homeostasis by regulating PTH release via "sensing" of its physiological agonist, Ca2+o. Its cloning from rat striatum revealed that the extracellular calcium-sensing receptor (CaR) could be involved in sensing ambient Ca2+o within the brain, where Ca2+ plays key roles in virtually all aspects of central nervous system (CNS) function. The CaR is expressed in neurons, oligodendrocytes, microglia and the human astrocytoma cell line, U87 where its functions include control of cellular proliferation and modulation of ion channels, such as outward K+ channels and nonselective cation channels (NCC). In this report, we have shown that the CaR is expressed in U373 cells as assessed by RT-PCR using CaR-specific primers followed by sequencing of the amplified products, by Northern blot analysis using a CaR-specific probe as well as by Western analysis utilizing a specific polyclonal anti-CaR antiserum. Furthermore, agents known to activate the cloned CaR induce increases in cellular proliferation and the open probability of an NCC. Thus our study strongly suggests that elevated levels of Ca2+o, acting via the CaR, activate an NCC that could contribute to the associated CaR-induced stimulation of proliferation.

Facilitory paratonia and frontal lobe functioning

OBJECTIVE

To learn if paratonia predicts frontal cognitive impairments.

BACKGROUND

Paratonia, an alteration of tone to passive movement, can be divided into oppositional paratonia ("gegenhalten," "paratonic rigidity") and facilitory paratonia. Although paratonia has been thought to be induced by frontal lobe dysfunction, previous studies suggest that paratonia does not correlate with cognitive impairment. However, only oppositional paratonia has been studied in this manner, and in these studies only the presence or absence of paratonia was assessed instead of a quantitative scale. Facilitory paratonia has not been studied for its relation to cognitive function.

METHODS

Twenty-five patients evaluated for degenerative dementia were assessed on semiquantitative 5-point scales for paratonia by two independent raters. A quantifiable test--the modified Kral procedure--which assesses continued movement by the patient after cessation of passive movement was also administered for comparison with facilitory paratonia. To assess frontal lobe function, subjects were tested for echopraxia, distractibility, and word fluency. To screen for other cognitive defects, subjects were given the Mini-Mental State Examination (MMSE).

RESULTS

The modified Kral procedure strongly correlated with subjective rating of facilitory paratonia. This correlation was significantly stronger than the correlation with oppositional paratonia. The modified Kral procedure was also highly predictive of echopraxia, but was less predictive of other frontal lobe tests. Facilitory paratonia, oppositional paratonia, and the modified Kral procedure each strongly predicted scores on the MMSE.

CONCLUSIONS

Both facilitory and oppositional paratonia strongly predict general cognitive performance. The modified Kral procedure is a reliable indicator of facilitory paratonia and a predictor of impaired performance on frontal lobe tests.

Incidence studies of primary and secondary intracranial tumors: a systematic review of their methodology and results

We reviewed the incidence studies of intracranial tumors to compare their methodology and identify whether there was evidence of true differences in incidence by time, place, age, or sex. Studies were identified from Medline (1966-95), bibliographies of relevant articles, and personal knowledge. For each study, various methodological details were recorded, along with the age-standardized incidence of all primary tumors and the crude and age/sex-specific incidences of different types of intracranial tumor. Methodological factors which significantly influenced the reported incidence were identified and the results of different studies were compared and combined in a meta-analysis if appropriate. Twenty studies (over 20,000 primary tumors) were included. Higher incidences of primary tumors were found in studies that: used many methods to identify cases (odds ratio [OR] 1.92); included a high percentage of asymptomatic patients (OR 2.03); did not require histologic confirmation of the diagnosis (OR 1.69). Studies from the 1980's reported higher incidences than in previous decades (OR 1.51), probably because of improved methodology. Comparable studies from the 1980's gave widely different incidence rates for all primary tumors (7.1-18.6 per 100,000 per year). In all studies, the incidence of neuroepithelial and meningeal tumors increased dramatically with age. Neuroepithelial tumors were 40% more common in men, whilst meningeal and cranial nerve tumors were about 80% and 40% more common in women, respectively. Further incidence studies are required to establish geographical and secular variations in the incidence of primary intracranial tumors but these must use comparable methodologies. Provisional guidelines for future studies are given.

Occupational exposures to metals as risk factors for Parkinson's disease

In a population-based case-control study, we investigated the potential role of occupational exposure to iron, copper, manganese, mercury, zinc, and lead as risk factors for Parkinson's disease (PD). Concurrently recruited, nondemented patients (n = 144) with idiopathic PD and controls (n = 464) consisting of men and women > or =50 years of age, frequency-matched for age (within 5 years), race, and sex were enrolled. All had primary medical care at Henry Ford Health System in urban/suburban metropolitan Detroit. Subjects were given an extensive risk-factor questionnaire detailing actual worksite conditions of all jobs held for more than 6 months from age 18 onward. An industrial hygienist, blinded to the case-control status of subjects, rated occupational exposure to each of the metals of interest. When adjusted for sex, race, age, and smoking status, we found in those with more than 20 years' exposure a significantly increased association with PD for copper (OR = 2.49, 95% CI = 1.06, 5.89) and manganese (OR = 10.61, 95% CI = 1.06, 105.83). For more than 20 years' exposure to combinations of lead-copper (OR = 5.24, 95% CI = 1.59, 17.21), lead-iron (OR = 2.83, 95% CI = 1.07, 7.50), and iron-copper (OR = 3.69, 95% CI = 1.40, 9.71), there was a greater association with PD than with any of these metals alone. These findings suggest that chronic exposure to these metals is associated with PD, and that they may act alone or together over time to help produce the disease.

Incidence of intracranial tumours in the Lothian region of Scotland, 1989-90

OBJECTIVE

To determine the incidence of primary and secondary intracranial tumours in the Lothian region of south east Scotland.

METHODS

A population based study was performed. Patients from Lothian with incident intracranial tumours diagnosed in 1989 and 1990 (by CT or histology) were identified retrospectively using multiple sources. Differences in incidence by tumour type, age, sex, and socioeconomic status were examined.

RESULTS

Four hundred and forty two patients with incident intracranial tumours were identified (228 primary tumours and 214 secondary tumours). The crude yearly incidences of primary and secondary tumours were 15.3 and 14.3 per 100,000 respectively. The commonest primary tumours were neuroepithelial tumours (53.5%), meningeal tumours (19.5%), and sellar tumours (16.5%). About 50% of patients with secondary tumours had an underlying lung cancer. The incidence of primary and secondary tumours increased markedly with age. Meningeal tumours were more common in women, and neuroepithelial tumours were more common in those who lived in more affluent areas.

CONCLUSIONS

The incidence rates of primary and secondary intracranial tumours in Lothian were more than twice those previously reported in the United Kingdom. Intracranial tumours are a significant cause of morbidity and mortality in the United Kingdom, and further research into their aetiology and treatment is urgently required.