Elevated plasma histamine in chronic uremia. Effects of ketotifen on pruritus.

A role for histamine in the pathogenesis of uremic pruritus was investigated in maintenance hemodialysis patients. Venous plasma histamine levels, as determined by radioenzymatic assay, were significantly higher (p less than 0.05) in hemodialysis patients with pruritus (368 +/- 103 pg/ml [mean +/- SEM], n = 6) than in those without pruritus (146 +/- 22 pg/ml, n = 5) and in normal controls (142 +/- 16, n = 5). Arteriovenous fistula histamine levels (202 +/- 52 pg/ml, n = 6) were significantly lower (p less than 0.05) than simultaneously drawn venous samples. Markedly elevated histamine-degrading enzyme (histaminase) activities were found in both hemodialysis patients with (2.95 +/- 0.18 pg histamine degraded/minute) and without (2.44 +/- 0.28) pruritus, but was undetectable in normal controls. Histaminase activities did not significantly differ in simultaneously drawn venous and fistula samples. With hemodialysis, histaminase activities fell significantly (p less than 0.01), whereas plasma histamine did not change. We further examined the effects of ketotifen, a putative mast cell stabilizer, on severe uremic pruritus. Five of five patients had significant (p less than 0.01) reductions in pruritus, as judged on a six-point pruritus index, after 8 weeks of drug (x = 2.3), as compared to conventional therapy (x = 5.9). Despite these improvements, no significant differences were noted in pre- versus post-drug plasma histamine levels, histaminase activities, or the histamine content per gram of skin biopsy specimen. These data support prior hypotheses that mast cell activation contributes to the pruritus of uremia.

Raised histamine concentrations in chronic cholestatic liver disease.

Pruritus is a frequent symptom in chronic cholestatic liver disease. To date, no single causative mechanism has been identified. We examined venous plasma concentrations of the known pruritogen, histamine, using a highly sensitive radioenzymatic assay in 42 patients with chronic cholestatic liver disease, and in normal controls. The mean plasma histamine level was significantly greater in chronic cholestatic liver disease patients (275 (117) pg/ml; X (SD) than in controls (140 (72) pg/ml, n = 20) (p less than 0.0001). No significant differences were found between histamine concentrations in the two chronic cholestatic liver disease subgroups: primary biliary cirrhosis and sclerosing cholangitis. Histamine concentrations were significantly greater (p less than 0.01) in the pruritic (319 (132) pg/ml) as compared with the non-pruritic (227 (75) pg/ml) chronic cholestatic liver disease patients. The histaminase activity was equivalent in patients and controls. The finding of raised histamine concentrations in chronic cholestatic liver disease suggests in vivo mast cell activation and a potential role for its mediators in the pruritus characteristic of these disorders.

A new versatile transbronchial cytology needle for the staging and diagnosis of bronchogenic carcinoma.

A new versatile transbronchial needle, the modified type 2B retractable needle, was used for the staging and diagnosis of bronchogenic carcinoma. It combines the advantages of its predecessors, the fixed type 1A needle and the retractable type 2A needle, such as convenience of usage and the added ability to sample peripheral as well as central lesions. The new modified type 2B retractable needle provides better protection of the airways and bronchoscope than the fixed type 1A needle and eliminates the type 2A needle's requirement for total removal of the guidewire before aspiration. The new type 2B needle was compared with either the original fixed type 1A or the retractable type 2A needle in 20 patients at 34 transbronchial sites and found a similar diagnostic yield. The modified type 2B retractable needle was the most versatile needle of those studied and can be used for transbronchial needle aspiration of both central and peripheral lesions.