The primary structure of rat ribosomal protein L7. The presence near the amino terminus of L7 of five tandem repeats of a sequence of 12 amino acids

The covalent structure of rat ribosomal protein L7 was determined in part from the sequence of nucleotides in a recombinant cDNA and in part from the sequence of amino acids in portions of the protein. The complementary analyses supplemented and confirmed each other. Ribosomal protein L7 contains 258 amino acids and has a molecular weight of 30,040. The protein has an unusual and striking structural feature near the NH2 terminus: five tandem repeats of a sequence of 12 residues. Rat L7 appears to be related to ribosomal protein L7 from the moderate halophile Vibrio costicola and perhaps to L30 from Bacillus stearothermophilus, to L7 from the moderate halophile NRCC 41227, and to L22 from Nicotinia tobaccum chloroplast. In addition, there is a sequence of 24 amino acids in rat protein L7 that may be related to segments of the same number of residues in Escherichia coli ribosomal proteins S10, S15, L9, and L22.     

Treatment of osteoporosis with human parathyroid peptide and observations on effect of sodium fluoride.

OBJECTIVE--To evaluate the need for a randomised study of treatment of spinal osteoporosis with human parathyroid peptide in the secondary prevention of crush fractures; to study the effect of human parathyroid hormone peptide 1-34 plus sex hormones on vertebral body cancellous bone; and, separately, to determine the effect of relatively low doses of sodium fluoride plus calcium on spinal bone mineral density. DESIGN--Open study of patients with primary or postmenopausal osteoporosis. All patients had serial bone densitometry of the spine by quantitative computed tomography and dual photon absorptiometry as well as serial densitometry of the radial midshaft (cortical) and radial distal (trabecular) bone by quantitative computed tomography. Changes in the spinal bone not forming the spongiosa of the vertebral bodies ("cortical" bone) were determined from the difference between the two axial measurements, after correction to the same units of measurement. SETTING--Northwick Park Hospital and Medical Research Council Clinical Research Centre. PATIENTS--24 Patients who fulfilled the conventional criteria for type 1 (vertebral) osteoporosis not secondary to recognised causes other than sex hormone deficiency and with at least one crush or wedge vertebral fracture and a spinal bone density (quantitative computed tomography) less than 80 mg/cm3 or two or more fractures. Twelve patients received human parathyroid peptide and 12 sodium fluoride; they were not randomised. MAIN OUTCOME MEASURES--Trends in axial and peripheral bone mass values determined by linear, time dependent regression analyses. RESULTS--The patients receiving the peptide showed a substantial increase in vertebral spongiosa (mean 25.6 mg/cm2 two years after the start of treatment). No significant changes were seen in spinal cortical or radial bone density. The patients receiving sodium fluoride showed roughly equal increases in cancellous and cortical bone over the same period (mean increase in vertebral spongiosa 16.1 mg/cm3). No significant changes were seen in radial bone. CONCLUSIONS--Treatment of postmenopausal women with human parathyroid peptide selectively increases spinal cancellous bone density by amounts that may prove useful in secondary prevention. Peptide treatment should now be tested in a randomised study in which the important end point is prevention of fractures as the usefulness of sodium fluoride in this context is doubtful.     

Adeno-associated virus: a vector system for efficient introduction and integration of DNA into a variety of mammalian cell types.

Adeno-associated virus (AAV) is a single-stranded DNA parvovirus that is dependent on adenovirus or herpesvirus for reproductive functions. We describe the construction of recombinant AAV vectors containing the chloramphenicol acetyltransferase gene or the neomycin phosphotransferase gene. These vectors carried their respective genes into a wide variety of cell types, including primary skin fibroblasts and hematopoietic cells. Infection efficiencies varied with cell type and ranged up to 3.0%. Coinfection of two different recombinant viruses was also used to introduce two different sequences simultaneously into a given cell. Finally, methods for obtaining recombinant AAV vectors with minimal contamination of wild-type virus are described. These various attributes of AAV vectors make them a viable DNA transduction system.     

Sister chromatid exchange distribution in various human tissues exposed to MMC and BrdU

The effect of two known mutagens on different human tissues was examined in an attempt to determine if tissue specific responses exist in SCE distribution on chromosome. The tissues included human lymphocytes, skin fibroblasts, ovarian and testicular cells. All cell types were exposed to varying concentrations of 5-bromodeoxyuridine (BrdU), and mitomycin C (MMC). The numbers of SCEs were recorded from each tissue. Results indicated that certain of the tissues tested appeared more sensitive to particular agents. Results also showed that in all the tissues tested the larger chromosomes in groups A to C had greater numbers of SCEs than did the smaller chromosomes in groups D to G. There were very few SCEs in F and G group chromosomes including Y.     

Activated human monocytes oxidize low-density lipoprotein by a lipoxygenase-dependent pathway

Monocyte-mediated oxidation of low-density lipoprotein (LDL) converts the lipoprotein to a potent cytotoxin. The oxidation process requires monocyte activation and requires superoxide anion since it can be blocked by superoxide dismutase. In this study, the requirement for lipoxygenase activity is shown, in that 1) inhibitors of lipoxygenase prevent the alteration of LDL, 2) copper (II) (3,5-diisopropylsalicylic acid), an agent shown to enhance lipoxygenase activity in a cell-free system, similarly enhances monocyte-mediated LDL alteration, and 3) the (3,5-diisopropylsalicylic acid)-enhanced monocyte-mediated modification of LDL can be completely blocked by inhibitors of lipoxygenase or by superoxide dismutase. These data suggest an integral role for monocyte lipoxygenase in the generation by activated monocytes of the extracellular superoxide anion that participates in the oxidation of LDL and the conversion of LDL to a cytotoxin. Monocyte-modified LDL may be a mediator in tissue damage that accompanies atherosclerosis or occurs at sites of inflammation.     

Full-length rat alpha and beta cardiac myosin heavy chain sequences. Comparisons suggest a molecular basis for functional differences

The two cardiac myosin heavy chain isoforms, alpha and beta, differ functionally, alpha Myosin exhibits higher actin-activated ATPase than does beta myosin, and hearts expressing alpha myosin exhibit increased contractility relative to hearts expressing beta myosin. To understand the molecular basis for this functional difference, we determined the complete nucleotide sequence of full-length rat alpha and beta myosin heavy chain cDNAs. This study represents the first opportunity to compare full-length fast ATPase and slow ATPase muscle myosin sequences. The alpha and beta myosin heavy chain amino acid sequences are more related to each other than to other sarcomeric myosin heavy chain sequences. Of the 1938 amino acid residues in alpha and beta myosin heavy chain, 131 are non-identical with 37 non-conservative changes. Two-thirds of these non-identical residues are clustered, and several of these clusters map to regions that have been implicated as functionally important. Some of the regions identified by the clusters of non-identical amino acid residues may affect actin binding, ATP hydrolysis and force production.     

Ventricular myosin light chain 1 is developmentally regulated and does not change in hypertension.

Cardiac myosin heavy chain (MHC) isoform distribution has been shown to undergo changes during development, in response to hormonal stimuli, and during pathologic states like hypertension. We initiated a study of myosin light chain 1 (MLC1) expression in cardiac tissue to determine whether MLC1 undergoes changes similar to those seen for MHC. We isolated a full length cDNA for the predominant MLC1 sequence in rat hearts. This gene is expressed in ventricular tissue at much higher levels than in atrial tissue. Based on its expression pattern and sequence homology, this cDNA encodes the rat ventricular MLC1 and has been named RVMLC1. RVMLC1 is expressed at very low levels in cardiac tissue during early development and is expressed abundantly after birth and in adult hearts. The expression of RVMLC1 was found not to change in the hearts of rats with renovascular hypertension.