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We investigated the prevalence and characteristics of intestinal alkaline phosphatase (ALP; EC 3.1.3.1) identified in human serum by cellulose acetate electrophoresis in 8% of fasting serum samples from hospital patients (n = 500) and in 35% of fasting serum samples from patients with diabetes mellitus (n = 106; not differentiated between types 1 and 2). The intestinal ALP electrophoretic band was usually heterogeneous and contained two major subtypes of ALP. Isoelectric focusing of intestinal-ALP-positive serum treated with levamisole and neuraminidase (EC 3.2.1.18) revealed two distinct regions of enzymatic activity that comigrated with ALP extracted from small intestinal and colonic mucosa. Anodic intestinal ALP was resistant to treatment with levamisole and neuraminidase and comigrated with ALP from small intestinal mucosa. The more-cathodic intestinal ALP, which comigrated with ALP from colonic mucosa, was completely inhibited by levamisole and converted by neuraminidase to a species with a more basic pI than that of neuraminidase-digested tissue-nonspecific form. This component of intestinal ALP may be of vascular origin.

The biuret method for total protein has been compared on the Boehringer Mannheim Diagnostics (BMD) Hitachi 717 Analyzer with a candidate reference method in efforts to standardize the BMD method. The methods were compared using 115 paired serum specimens collected during morning rounds at the Roger Williams Hospital. Results from the test method were compared to the reference method using a statistical procedure for quantifying bias between analytical methods. Linear regression statistics were also calculated. The Hitachi 717 biuret method shows no bias when compared to the reference method (z = -0.90), and there is acceptable correlation between the two methods (y = 0.86, m = 0.86, r = 0.896). The Hitachi method is linear to 15.0 g per dL and demonstrates excellent precision (CV less than or equal to 2.14 percent, N = 140). The Hitachi 717 biuret method has been found to be excellent in all respects and its use is recommended as a convenient and accurate means of measuring total protein.

Two cell lines, RW-2982 and RW-7213, have been established for the first time from the mucinous variant of human colorectal carcinoma, which is a distinctive and important subtype that has a worse prognosis than the more common nonmucogenic large bowel carcinoma. Methods of establishment and observations made during 7 and 3 years, respectively, of continuous culture are described. These cell lines required 4-9 months of adaptation to tissue culture conditions before noticeable growth occurred. Both cell lines have the following unique properties: (a) growth in vitro as delicate branching three-dimensional tumor particles within a wide gel of insoluble, often translucent mucus (proteoglycan); (b) production of large quantities of carcinoembryonic antigen; (c) ability to survive or adapt to growth in media free of serum, hormones, growth factors, and all protein; and (d) tumorigenicity in multiple sites in nude mice, including liver, with especially rapid growth in the peritoneal cavity as gelatinous material that is nonadherent and noninvasive and thus resembles pseudomyxoma peritonei. Unlike other reported colorectal cell lines, these mucus-coated particulate cell lines will not readily grow as monolayers and grow much more slowly with a doubling time of 2 weeks or more. A serially transplantable tumor from the RW-7213 surgical specimen has also been maintained in nude mice since August 8, 1984. This tumor retains properties of the original specimen. Observations made on the tumor biology of mucogenic colorectal carcinoma using these cell lines are discussed.

Gentamicin is a nephrotoxic agent known to damage the proximal tubule,--a site of low molecular weight (LMW) protein reabsorption and catabolism. The effect of gentamicin was investigated on three LMW proteins--amylase, light chains, and beta 2 microglobulin--and the effects were correlated on the latter to renal function as determined by creatinine clearance (GFR). The renal excretion of beta 2 microglobulin (beta 2M) was studied in 18 patients receiving gentamicin and eight control patients. Both gentamicin and control patients had similar mean ages and serum beta 2M. Twelve of the 18 gentamicin treated patients had marked increases in beta 2M excretion. The mean daily 2 beta microglobulin excretion for the gentamicin treated group was 10,511 microgram while that of the control group was 102 microgram. Serial determinations in 10 of the gentamicin treated patients revealed an increase in beta 2M excretion within 48 hours of starting therapy. No deterioration of GFR was seen in any patient. In four patients, beta 2M excretion decreased while still receiving gentamicin. The renal handling of amylase was found to be normal in four patients and mildly abnormal in three patients receiving gentamicin who also had increased beta 2M excretion. Urinary light chains were determined in four of these seven patients and found to be normal. It is concluded that gentamicin induces an early and often transient tubular proteinuria. This tubular proteinuria is not associated with clinical nephrotoxicity.