Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a chance observation, a 74-year-old woman was found to have hypercalcaemia (3.0 mmol/l) and multiple skeletal osteolyses. A diagnosis of multiple myeloma was made after the demonstration of paraproteins in serum (IgG-kappa) and a 10% proportion of plasma cells in a pelvic crest biopsy. Oral chemotherapy with melphalan and prednisone failed to alter the calcium level. Simultaneous increase in alkaline phosphatase and reduction in serum phosphate concentration led to further tests: determination of peripheral venous parathormone concentration, ultrasound examination of the neck, thallium-technetium subtraction scintigraphy and selective venous parathormone measurements. The results demonstrated the coexistence of primary hyperparathyroidism. The calcium level became normal after surgical removal of a parathyroid adenoma.
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PMID:[Hypercalcemia in coexistent parathyroid adenoma and multiple myeloma. Problems of differential diagnosis]. 266 81

N-Glycolylneuraminic acid (Neu5Gc) is an oncofetal antigen in humans and is developmentally regulated in rodents. We have explored the biology of N-acetylneuraminic acid hydroxylase, the enzyme responsible for conversion of the parent sialic acid, N-acetylneuraminic acid (Neu5Ac) to Neu5Gc. We show that the major sialic acid in all compartments of murine myeloma cell lines is Neu5Gc. Pulse-chase analysis in these cells with the sialic acid precursor [6-3H]N-acetylmannosamine demonstrates that most of the newly synthesized Neu5Gc appears initially in the cytosolic low-molecular weight pool bound to CMP. The percentage of Neu5Gc on membrane-bound sialic acids closely parallels that in the CMP-bound pool at various times of chase, whereas that in the free sialic acid pool is very low initially, and rises only later during the chase. This implies that conversion from Neu5Ac to Neu5Gc occurs primarily while Neu5Ac is in its sugar nucleotide form. In support of this, the hydroxylase enzyme from a variety of tissues and cells converted CMP-Neu5Ac to CMP-Neu5Gc, but showed no activity towards free or alpha-glycosidically bound Neu5Ac. Furthermore, the majority of the enzyme activity is found in the cytosol. Studies with isolated intact Golgi vesicles indicate that CMP-Neu5Gc can be transported and utilized for transfer of Neu5Gc to glycoconjugates. The general properties of the enzyme have also been investigated. The Km for CMP-Neu5Ac is in the range of 0.6-2.5 microM. No activity can be detected against the beta-methylglycoside of Neu5Ac. On the other hand, inhibition studies suggest that the enzyme recognizes both the 5'-phosphate group and the pyrimidine base of the substrate. Taken together, the data allow us to propose pathways for the biosynthesis and reutilization of Neu5Gc, with initial conversion from Neu5Ac occurring primarily at the level of the sugar nucleotide. Subsequent release and reutilization of Neu5Gc could then account for the higher steady-state level of Neu5Gc found in all of the sialic acid pools of the cell.
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PMID:Biosynthesis of N-glycolyneuraminic acid. The primary site of hydroxylation of N-acetylneuraminic acid is the cytosolic sugar nucleotide pool. 268 73

A 70-yr-old man with multiple myeloma IgD developed a plasma cell leukemia producing a serum IgD monoclonal peak and lambda light chains in the urine. When the serum and the urine were heated at 56 degrees C for 30 min both monoclonal bands disappeared. The precipitate failed to redissolve on heating to 100 degrees C. Ion exchange chromatography with a linear gradient of phosphate buffer, pH 8, 0.020-0.300 mol/l and column electrofocusing showed that the serum pyroglobulin was eluted with buffer concentration between 0.040-0.125 mol/l and had an isoelectric point of 5.02, while the pyroglobulin of the urine was eluted with 0.020-0.033 mol/l and had a pI = 7.16. The serum and urine pyroglobulins had a total antigenic community with their correspondent purified proteins. The isolated lambda chains did not change when they were heated at 56 degrees C for 30 min, nevertheless, the heated purified IgD shows some changes in its isoelectric point, molecular mass and antigenicity. These changes in the purified IgD suggest that the pyroprecipitability could be due to conformational features.
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PMID:IgD plasma cell leukemia associated with pyroglobulinemia and pyroglobulinuria. 308 61

The crystal structure of the Fab of McPC603, a phosphocholine-binding mouse myeloma protein, has been refined at 2.7 A resolution by a combination of restrained least-squares refinement and molecular modeling. The overall structure remains as previously reported, with an elbow bend angle between the variable and constant modules of 133 degrees. Some adjustments have been made in the structure of the loops as a result of the refinement. The hypervariable loops are all visible in the electron density map with the exception of three residues in the first hypervariable loop of the light chain. A sulfate ion occupies the site of binding of the phosphate moiety of phosphocholine.
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PMID:Phosphocholine binding immunoglobulin Fab McPC603. An X-ray diffraction study at 2.7 A. 309 27

Two patients, one with myeloma (Patient 1) and the other with probable chronic lymphocytic leukemia (Patient 2), had reduced renal tubular phosphate reabsorption in the absence of hyperparathyroidism together with other features of the Fanconi syndrome, as consequences of the nephropathy associated with light-chain proteinuria. Both patients had hypophosphatemic osteomalacia, demonstrated for the first time in this condition by iliac bone histomorphometry after in vivo double tetracycline labeling, despite absence of bone pain or Looser zones. Neither patient was vitamin D-depleted, but plasma calcitriol level was normal in Patient 1 and low in Patient 2; only the latter patient had severe muscle weakness. Complete histologic correction of osteomalacia was achieved by treatment in accordance with the biochemical defects--oral phosphate therapy alone in Patient 1 and combined with calcitriol in Patient 2. Both patients are now symptom-free, five and three years after the initial diagnosis of bone disease and hematogenous malignancy. Thirteen previous instances of the same form of osteomalacia were reviewed; in most cases, the Fanconi syndrome developed before its probable cause became apparent. The Fanconi syndrome has also been reported in two cases of osteomalacia due to mesenchymal tumor, but not in osteomalacia associated with prostatic carcinoma. Light-chain nephropathy and consequent renal tubular dysfunction appears to be a third form of oncogenous osteomalacia.
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PMID:Hypophosphatemic osteomalacia and adult Fanconi syndrome due to light-chain nephropathy. Another form of oncogenous osteomalacia. 310 97

A patient with IgG kappa myeloma had markedly elevated serum phosphate concentrations but no clinical features of hyperphosphataemia. The hyperphosphataemia was due to a high phosphate per protein unit than normal IgG.
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PMID:Phosphate binding by a myeloma protein. 311 64

Uptake of Tc-99m MDP by extraskeletal tissues is a rare, serendipitous finding during bone scanning studies. It can be clinically correlated with the presence of hypercalcemia in association with renal failure, as may occur in multiple myeloma. While the precise mechanism of non-osseous uptake of MDP is not certain, it may represent metastatic calcification based upon histological examination. A critical calcium-phosphate ion product appears to be requisite for deposition within soft tissues, and all cases in the literature for which data were available exceeded this ion product value. While MDP bone scanning is not generally useful in the diagnosis or staging of multiple myeloma, these findings may indicate secondary effects of the disease. The authors report the first case of liver, spleen, and lung uptake by MDP in a patient with hypercalcemia secondary to multiple myeloma, with a review of the literature.
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PMID:Non-osseous bone scan abnormalities in multiple myeloma associated with hypercalcemia. 324 15

Phycocyanin is a phycobiliprotein with peak absorption at 620 nm. The laser activation, cytotoxic effects, and uptake into atherosclerotic plaque of phycocyanin was studied. Optimal activation was produced by argon dye laser at 0.5 W and a total energy dose of 300 J/cm2 at 620 nm and 650 nm, irradiated through blood with a hematocrit of 8%. Activation was evidenced by reduction of optical density by 0.3 units at 340 nm caused by oxidation of the reduced nicotinamide adenine dinucleotide phosphate (NADPH) in a buffered reaction solution containing 0.1 mg/ml of phycocyanin. Cytotoxicity was evaluated by measuring viability of mouse myeloma cells in culture after incubation with phycocyanin (0.25 mg/ml) and irradiated by 300 J/cm2 at 514 nm. After 72 hours post-treatment the cells showed 15% viability compared to 69% and 71% for control cells exposed to laser only or phycocyanin only, respectively. Atherosclerotic artery segments obtained within 5 hours postmortem were perfused with 0.1 mg/ml phycocyanin in oxygenated Krebs Ringer solution at 30 mm Hg for 5 minutes followed by washout with phycocyanin-free Krebs for 10 minutes. Artery sections examined histologically by light and fluorescence microscopy showed specific fluorescence localization within the plaque particularly at the elastic laminae and to a larger extent at the internal elastic lamina but not in the medial muscle layer. In conclusion, phycocyanin is a cytotoxic photosensitizer that exhibits specific binding to plaque and is activated at a wavelength minimally absorbed by blood. These properties suggest potential therapeutic use for plaque localization and regression.
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PMID:Phycocyanin: laser activation, cytotoxic effects, and uptake in human atherosclerotic plaque. 335 51

Hypercalcemia is frequently observed in patients with multiple myeloma and renal failure. Whether Bence Jones protein (BJP) is directly nephrotoxic and how and whether hypercalcemia might contribute to this putative nephrotoxicity is currently unclear. To examine this issue, we studied the effect of modest hypercalcemia on the glomerular filtration rate (GFR) of rats exposed to a BJP that by itself had been found to be nonnephrotoxic. Three groups of rats were studied. All were anesthetized and underwent a baseline measurement of inulin clearance (Cin). After this, group 1 (n = 13) rats were given 2 ml of vehicle (phosphate-buffered saline solution [PBS]) and were then made hypercalcemic with an infusion containing 0.048 mol/L CaCl2. At the end of 2 hours a second Cin was measured. Group 2 rats (n = 8) were given 100 mg BJP in 2 ml PBS and a non-calcium-containing infusate. Group 3 (n = 11) rats were given 100 mg of the BJP in 2 ml PBS and then the calcium-containing infusate used in group 1 rats. Rats in groups 2 and 3 also had a second Cin measured at the end of 2 hours. Renal blood flow was measured with an electromagnetic flow probe. At the completion of the second clearance, kidneys were processed for renal histologic assessment. The serum calcium level measured during the second Cin period was 13.5 mg/dl for group 1, 7.9 mg/dl for group 2, and 13.7 mg/dl for group 3. No significant decrement in GFR was observed in group 1 or 2 rats. In contrast, group 3 rats had a 46% fall in GFR.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hypercalcemia can potentiate the nephrotoxicity of Bence Jones proteins. 365 25

In untreated serum of three patients with multiple myeloma, concentrations of inorganic phosphate ranged from 130 to 270 mg/L as measured with a chromogenic assay based on the interaction of phosphate ion with ammonium molybdate in the presence of ferrous sulfate. There were no clinical features of hyperphosphatemia, and values for total calcium concentration in serum remained within normal limits throughout. Subsequent investigations demonstrated that this hyperphosphatemia was spurious and was caused by high concentrations of the paraprotein interfering with the chromogenic assay. Because this type of assay, adapted for automated systems, is now widely used in clinical laboratories, we call attention to this limitation to avoid confusion in clinical evaluations of patients with multiple myeloma.
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PMID:Paraprotein interference with colorimetry of phosphate in serum of some patients with multiple myeloma. 373 47


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