Why do we speak with the left hemisphere?

Human language tends to be associated with circuitry in the left cerebral hemisphere, regardless of individual hand dominance. This may have resulted from the coevolution of language and dexterous manipulation, specifically the use of the dominant hand to direct forces and point to objects in the environment. Asymmetric manipulation of physical objects reflects a fundamental asymmetry of perceptual-motor brain circuitry, which in turn results from the nature of the mechanical interaction between the organism and its environment. The natural selection of more effective manipulative ability, especially in the form of tool use, strengthened the fundamental organismal asymmetry, leading to distinct handedness and hemispheric dominance for manipulation and language in humans. The related subject of ocular dominance is also discussed.

Why are vertebrate nervous systems crossed?

Contralateral central nervous control may be an evolutionary consequence of dependence on the image-forming eye, especially in large organisms. As a result of the topological transformation of the visual stimulus in the pupillary eye, the external environmental hemispace impinges directly upon the contralateral internal organismal hemispace. Selective pressure leads to the development of central connections capable of the most rapid and precise functional association of the internal milieu with the organism's environment. The consequence is contralateral central sensorimotor control. Previous hypotheses are discussed, including those based on bilaterality, binocularity the optic chiasm and avoidance behaviors.

The cervical spine in patients with psoriatic arthritis: a clinical, radiological and immunogenetic study.

The radiological changes of the cervical spine were evaluated in 57 patients with psoriatic arthritis and were correlated with clinical, radiological, and immunogenetic features of the disease. Forty patients (70%) showed radiological evidence of the cervical spine being affected by the disease. Two patterns of cervical spine abnormalities were noted. Fifteen patients (26%) had erosive and/or subluxing cervical rheumatoid like lesions; 25 patients (44%) had a more frequently reported pattern similar to ankylosing spondylitis. Although subaxial subluxations were the most frequently observed cervical abnormalities (53%) in the inflammatory subgroup, none of the patients studied had cord compression. Ankylosing cervical spine disease was the only form of axial involvement in nine (36%) of 25 patients with the ankylosing form of psoriatic arthritis. All of these patients had peripheral disease and were B27 negative. Predictors of cervical spine disease patterns were considered using clinical, demographic, and radiological features and HLA antigens. The results of a multivariate analysis showed that the best predictors of inflammatory cervical spine disease are the presence of HLA-B39 and HLA-DR4 antigens, radiocarpal erosions, and the absence of the HLA-DR5 antigen.

Epidemiologic and immunogenetic aspects of polymyalgia rheumatica and giant cell arteritis in northern Italy.

We studied the epidemiology of giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) in a Mediterranean population. Ninety-nine patients with PMR and/or GCA were identified over a 9-year period (1980-1988) in Reggio Emilia, Italy. The average annual incidence of PMR and GCA was 12.7/100,000 and 6.9/100,000, respectively, in a population aged 50 years or older. Frequencies of HLA antigens were determined in 49 patients with PMR and/or GCA who were followed by staff at our rheumatology unit during the 1980-1988 period. When compared with HLA findings in 242 healthy controls, DR4 was not found to be significantly associated with PMR (24% in PMR patients versus 14% in controls). Patients with GCA also showed an increased frequency of DR4 compared with controls (36% versus 14%), but this difference was also not statistically significant. The immunogenetic features of PMR and GCA and the relationship between the immunogenetic and epidemiologic patterns in different populations are discussed.

Bartter's syndrome and chondrocalcinosis: a possible role for hypomagnesemia in the deposition of calcium pyrophosphate dihydrate (CPPD) crystals.

A new case of association between Bartter's syndrome and chondrocalcinosis is reported. The patient was shown to have marked hypomagnesemia. Indomethacin and magnesium therapy was started and resulted in increased magnesemia, even if it did not reach normal levels. There was complete remission of articular symptoms and no progression on the radiological picture after 2 years of continuous magnesium and indomethacin therapy. The 7 available family members were studied to assess the possible presence of a familial form of chondrocalcinosis and/or hypomagnesemia. The literature is reviewed and reports of previously described associations between Bartter's syndrome and chondrocalcinosis are summarized. The possible role of hypomagnesemia in predisposing to deposition of calcium pyrophosphate dihydrate crystal in cartilagine is also discussed.

Clinical response to auranofin in patients with psoriatic arthritis.

Fifty-two patients with psoriatic arthritis (PA), treated with auranofin (AF), were entered into a one year prospective, open study. The total group showed a significant increase in frequency of HLA antigens A1 and B38, and a reduction of B5 when compared to healthy controls. There was a remission or an important improvement of disease in the 51% of 45 patients who completed the study. The rate of withdrawal due to side effects was low (8.8%) and the toxicity was mild in nature (diarrhoea and mucocutaneous rash). We prospectively sought predictors of response using HLA antigens, and clinical and laboratory parameters at the beginning of therapy. The only 3 factors found to be related to outcome were duration of psoriasis, physician and patient assessment of disease activity. No laboratory data or HLA specificities could be associated with substantial response to AF therapy.