We applied the polymerase chain reaction to detection of the pathogenic protozoan Toxoplasma gondii based on our identification of a 35-fold-repetitive gene (the BI gene) as a target. Using this procedure, we were able to amplify and detect the DNA of a single organism directly from a crude cell lysate. This level of sensitivity also allowed us to detect the BI gene from purified DNA samples containing as few as 10 parasites in the presence of 100,000 human leukocytes. This is representative of the maximal cellular infiltration (105/ml) in 1 mi of cerebrospinal fluid obtained from patients with toxoplasmic encephalitis. The BJ gene is present and conserved in all six T. gondii strains tested to date, including two isolates from patients with acquired immunodeficiency syndrome. No signal was detected by using this assay and DNAs from a variety of other organisms, including several which might be found in the central nervous system of an immunocompromised host. This combination of sensitivity and specificity should make detection of the BJ gene based on polymerase chain reaction amplification a very useful method for diagnosis of toxoplasmosis both in immunocompromised hosts and in congenitally infected fetuses.

Telogen effluvium (TE) is one of the most common causes of diffuse nonscarring hair loss. In its acute form, it generates a lot of anxiety in the patient, which can be significantly allayed with a confident diagnosis. In its more chronic form, however, the hair loss may go unnoticed for long periods of time. Here in, the dermatologist's role in differentiating it from the more common patterned hair loss is significant. Differentiating TE from other causes of diffuse nonscarring hair loss can indeed be a daunting task and TE is often used as a waste basket diagnosis. A number of factors have been implicated in the causation of TE, however, clear evidence in their support is lacking. The role of stress as a causative factor as well as the result of hair loss needs to be adequately understood. This review aims at summarizing our current level of knowledge with respect to this very common cause of hair loss. An attempt is made to help the readers reliably differentiate TE from other causes of diffuse nonscarring hair loss. The possible causative factors, pathogenetic mechanisms, clinical presentation, and possible treatment options are discussed.

Nail involvement in psoriasis is common, and the severity of it does not always parallel the intensity of cutaneous disease. We created a consensus group, of which the aim was to provide practical recommendations for the treatment of nail psoriasis in patients without skin psoriasis or with mild skin lesions with no indication for a systemic treatment. This collaborative process was conducted by an international panel of dermatologists with special expertise in nail disorders, using formal consensus methods. During this process, the panel strived to establish an agreement regarding the definition of nail psoriasis, the severity of nail psoriasis, and treatment response. Treatment recommendations are provided

Histopathological examination of nails is a valuable diagnostic aid, especially in the absence of skin lesions. Examination of the PAS-stained sections is necessary before making a histological diagnosis of nail psoriasis because onychomycosis and psoriasis may show similar histology.