Development of a sensitive two-site immunoradiometric assay for parathyroid hormone-related peptide: evidence for elevated levels in plasma from patients with adult T-cell leukemia/lymphoma and B-cell lymphoma.

We have developed a sensitive immunoradiometric assay for PTH-related peptide (PTHrP) using a monoclonal antibody against PTHrP(1-34) and a polyclonal antibody against PTHrP(50-83), with recombinant human PTHrP(1-87) as the standard. The detection limit of the immunoradiometric assay was 0.5 pmol/L, and plasma PTHrP(1-87) concentrations in 110 healthy subjects were 0.8 +/- 0.01 pmol/L, with the upper limit of the normal range being 1.1 pmol/L. Increased circulating PTHrP(1-87) concentrations were demonstrated in all 46 cancer patients with hypercalcemia, but not in patients with primary hyperparathyroidism, chronic renal failure, or hypoparathyroidism. Normalization of serum calcium levels after resection of tumors was shown to correlate well with that of plasma PTHrP(1-87) concentrations in 2 cancer patients. High circulating PTHrP(1-87) levels were also demonstrated in 12 out of 13 hypercalcemic patients with adult T-cell leukemia/lymphoma and in 7 out of 8 hypercalcemic patients with non-Hodgkin's lymphoma especially of B-cell type. These results suggest that PTHrP is a major humoral factor responsible for the hypercalcemia frequently associated with adult T-cell leukemia/lymphoma and also with B-cell lymphoma.

Differences in bone and vitamin D metabolism between primary hyperparathyroidism and malignancy-associated hypercalcemia.

Bone and vitamin D metabolism are examined in patients with primary hyperparathyroidism (1 degree HPT), humoral hypercalcemia of malignancy (HHM), and local osteolytic hypercalcemia (LOH) with normal renal function. Among the bone resorption markers, T scores of total deoxypyridinoline (Dpyd) were highest in HHM and were significantly higher than those in 1 degree HPT. Among the formation markers, T scores of osteocalcin (OC) were highest in 1 degree HPT but were negative in HHM. The elevation in total Dpyd was associated with an increase in OC in 1 degree HPT, and the ratios of total Dpyd/OC were similar to those in controls. In contrast, many patients with HHM and LOH exhibited elevated total Dpyd and suppressed OC with increased total Dpyd/OC ratios, but the ratios varied widely. Serum 1,25-dihydroxyvitamin D [1,25(OH)2D] was elevated in 1 degrees HPT but was suppressed in HHM and LOH at any serum Ca levels. These results demonstrate that increased bone resorption is associated with enhanced bone formation in 1 degrees HPT but are uncoupled in many of the HHM and LOH patients, and that total Dpyd/OC ratio can be a useful index to estimate the coupling state of bone. It is suggested that the reduction in serum 1,25(OH)2D cannot be explained by an elevation in serum Ca in HHM and LOH, and that the differences in bone and vitamin D metabolism in HHM and LOH from those in 1 degree HPT may be caused by a common mechanism such as the secretion of some cytokines from tumors.

Interaction of peptides derived from the Fas ligand with the Fyn-SH3 domain.

Interaction of the widely expressed Fas with its membrane-bound ligand (FasL) leads to rapid cell death via apoptosis. To avoid pathological tissue damage, the activity of FasL requires tight regulation. Here, we report that the Src homology 3 (SH3) domain of Fyn binds to the proline-rich cytoplasmic region of FasL. Binding of the SH3 domain occurs between amino acid residues 44-71 which contains several potential SH3 interaction sites. This binding is specific, as SH3 domains of Lck, Grb2 and ras-GAP bind only weakly or not at all. We suggest that FasL activity may be modulated by SH3 domains of the src-like Fyn kinase.

Mode of disulfide bond formation of a heat-stable enterotoxin (STh) produced by a human strain of enterotoxigenic Escherichia coli.

To determine the modes of three disulfide linkages in the heat-stable enterotoxin (STh) produced by a human strain of enterotoxigenic Escherichia coli, we synthesized STh(6-18), which consists of 13 amino acid residues and has the same intramolecular disulfide linkages as native STh [(1985) FEBS Lett. 181, 138-142], by stepwise and selective formation of disulfide bonds using different types of removable protecting groups for the Cys residues. Synthesis of the peptide with different modes of disulfide bond formation provided three peptides consistent with standard STh(6-18) in their physicochemical and biological properties, thereby indicating that the disulfide bonds in STh(6-18) are Cys-Cys-Glu-Leu-Cys-Cys-Asn-Pro-Ala-Cys-Thr-Gly-Cys.

A case-referent study on neuropsychiatric disorders among workers exposed to solvents.

Published reports give justification for the belief that long-term exposure to solvents might induce chronic but nonspecific neuropsychiatric conditions. This case-referent study of data from a regional Swedish pension fund register indicated a risk ration of 1.8 in regard to nonspecific neuropsychiatric disorders among workers such as painters, varnishers and carpetlayers who are exposed to solvents as compared to workers not so exposed. Moreover a dose-response relationship seems to exist between exposure in terms of occupational years and neuropsychiatric conditions, the result being that persons affected are considered eligible for disability pensions.

Nonsteroidal anti-inflammatory drugs induce hypermotilinemia and disturbance of interdigestive migrating contractions in instrumented dogs.

Nonsteroidal anti-inflammatory drugs (NSAIDs) induce gastric ulcers due to inhibition of prostaglandin production. Prostaglandins have an influence on physiological gastrointestinal motility, but the relationships between NSAID-induced gastric ulcer, gastrointestinal motility and motilin are unknown. Fifteen dogs were allocated randomly to three groups in which either gelatin, meloxicam or indomethacin was administered. Fecal occult blood and gastrointestinal motility were monitored continuously for 6 days. In addition, analyses of the plasma motilin concentration, gastrointestinal endoscopy and gastric emptying, and detection of motilin cells were performed. Gastrointestinal motility was disturbed in the indomethacin group, presenting as disappearance of interdigestive migrating contractions (IMCs) 3 days before gastric ulcers were detected. Delayed gastric emptying and hypermotilinemia were observed significantly more often in the indomethacin group compared with the other groups. Motilin cell-crypt/villi ratio in the indomethacin group significantly decreased in the duodenum and jejunum, compared with the other groups. No significant changes in any tests were observed in the meloxicam group, when compared with the gelatin group. These findings suggest that the disturbance of IMCs caused by hypermotilinemia, with changes in motilin cell distribution, and delayed gastric emptying induced by indomethacin may contribute to the development of gastric ulcers.

Some effects of nalidixic acid on conjugation in Escherichia coli K-12.

The role of deoxyribonucleic acid (DNA) synthesis in the Escherichia coli conjugation system has been studied using nalidixic acid (NAL) to specifically inhibit DNA synthesis in matings between reciprocal combinations of male (Hfr) and female (F(-)) mutants resistant and sensitive to NAL; the physiological action of NAL on the strains utilized was also studied. Matings between combinations of mutants resistant (Nal(r)) and sensitive (Nal(s)) to NAL allow various parental functions to be established: pair formation studies show that the female cells are responsible for the slight decrease in pair formation when NAL is present in Hfr(Nal(s)) x F(-) (Nal(s)) matings. Preformed mating pairs are stable in the presence of NAL. In matings between Hfr(Nal(s)) and F(-)(Nal(r)), the transfer gradient constant increases linearly with low NAL concentration (0.1 to 0.6 mug of NAL per ml). Higher concentrations of NAL (5 mug/ml) act on Nal(s) males to rapidly stop chromosome transfer; under these conditions, however, DNA degradation is unmeasurable as determined from single-strand nicking in the male cells. This result is consistent with a model for chromosome transfer which requires DNA synthesis in the male cell. Inhibition of DNA synthesis (by 85%) in the female has no effect on conjugal chromosome transfer. High concentrations of NAL (>20 mug/ml) produce slight inhibition in chromosome transfer for the Hfr(Nal(r)) x F(-)(Nal(r)) mating tested; this effect is probably caused by action of NAL on the male. The inhibition of chromosomal transfer by NAL appears to be irreversible in the normal sense. A pulse of NAL, applied during transfer, immediately stops the transfer which is in progress. On removal of the NAL block, the temporal appearance of recombinants is consistent with the idea that a new round of transfer has commenced from the sex factor location on the male chromosome.