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D M Brown

Publications and source records attributed to D M Brown.

At least 271 records · Page 15Linked to original sources
PubMed1982

Sensitive detection of RNA using strand-specific M13 probes.

We have extended the method of Hu and Messing (Gene 17 (1982) 271-277) to prepare highly radioactive M13 probes suitable for use in RNA-DNA hybridization experiments. Single strands of M13 DNA carrying cloned sequences are rendered partially double-stranded by primed synthesis using a synthetic oligonucleotide primer complementary to a region 5' to the cloning site. The newly synthesized radioactive complementary strand is then covalently cross-linked to the M13 phage DNA by UV irradiation in the presence of 4,5,8-trimethylpsoralen (trioxsalen). Since the cross-linked probe is stable to heat denaturation, and the region of cloned sequence is kept single-stranded, these complexes may be used as strand-specific hybridization probes to detect RNA sequences under conditions which would denature DNA-DNA duplexes.

Base Sequence↗
PubMed1982

Kidney complications.

Diabetic glomerulosclerosis in man and in all spontaneous-onset and chemically induced diabetes in experimental models is characterized by diffuse increase in mesangial matrix and glomerular basement membrane thickening. The most prominent features of the biochemical changes in the glomerular basement membrane are increase in the collagen-like components, decreased sialic acid, and increased glucosylation. However, the heterogeneity of the various glycoprotein components of the glomerular basement membrane and related components of the mesangium make comparative biochemistry difficult. Increased glomerular blood flow with no apparent alterations in the glomerular filtration coefficient in diabetes may be attributed to altered vascular control mechanisms which may include both hormonal mediation as well as changes in end-organ responsiveness. Although proteinuria is a common manifestation of diabetic involvement of the glomerulus, there is little biochemical or physiologic evidence as to the specific causes of increased glomerular filtration apparatus permeability. Further information as to the pathogenesis of diabetic vascular disease of the kidney and the ability to reverse pathologic changes by correction of the metabolic milieu will require analysis of carefully selected animal models. Particular care in experimental design must include the ability to integrate pathology, physiology, and biochemistry in each model in order to relate the information to human renal diabetic complications.

Animals↗
PubMed1982

35S-glycosaminoglycan and 35S-glycopeptide metabolism by diabetic glomeruli and aorta.

35S-glycosaminoglycan metabolism by glomeruli isolated from streptozotocin-diabetic and control rats was studied in vivo and in vitro. Total 35S-glycosaminoglycan synthesis and retention in the matrix by diabetic glomeruli was reduced while degradation was increased. 35S-glycosaminoglycan content of isolated GBM was similarly decreased. Whereas 35S-glycosaminoglycan content of glomeruli and GBM was decreased after in vitro incubation with 35SO4, a larger proportion of total 35S-glycosaminoglycans was found in the incubation medium from diabetic glomeruli. Both control and diabetic glomeruli synthesize 35S-labeled glycopeptides, the quantity from diabetic glomeruli being reduced. Aorta from 35SO4-injected diabetic rats also synthesized reduced quantities of 35S-glycosaminoglycans. There were no preferential metabolic alterations of species of 35S-glycosaminoglycans by diabetic glomeruli or aortas. These studies suggest that synthesis of 35S-glycosaminoglycans and 35S-glycopeptides by diabetic glomeruli are altered by disturbances of both synthetic as well as degradative pathways. An alteration of 35S-glycosaminoglycans interaction with matrix components in diabetes is postulated.

Animals↗
PubMed1981

Fetal rat lung phosphatidylcholine synthesis in diabetic and normal pregnancies: a comparison of prenatal dexamethasone treatments.

The effects of maternal diabetes upon fetal lung surfactant phospholipid metabolism were studied using 19-day gestational age fetal rats from mothers with streptozotocin-induced diabetes mellitus. In this experimental animal model, maternal glucose intolerance significantly impaired fetal body and lung development. However, incorporation of [14C]palmitate and [3H]choline into lung total and disaturated phosphatidylcholine was unimpaired in offspring of diabetic mothers. Dexamethasone, which is known to promote fetal lung maturation in normal pregnancies, was administered to diabetic and control mothers during late gestation. Prenatal dexamethasone inhibited lung growth in both diabetic and control pregnancies. While this agent slightly stimulated [14C]palmitate incorporation into total phosphatidylcholine and markedly enhanced [3H]choline incorporation into both disaturated and total phosphatidylcholine in control pregnancies, it failed to stimulate incorporation of either precursor into fetal lung from diabetic pregnancies.

Animals↗
PubMed1981

Glycosaminoglycan synthesis by glomeruli in vivo and in vitro.

The distribution of glycosaminoglycans in disrupted glomerular fractions was studied using 35SO4-labeling in vivo and in vitro. The majority of 35S of isolated glomerular basement membrane was found in heparan sulfate after in vivo and in vitro pulses, although the absolute proportion and the degrees of N-sulfation and N-acetylation varied with the conditions of exposure. Varying amounts of chondroitin sulfate and dermatan sulfate were found in the glomerular basement membrane fraction and larger proportions of both of these glycosaminoglycans as well as of heparan sulfate were found in various glomerular fractions. Glomerular glycosaminoglycans distribution studies must take into account the experimental conditions. Basement membrane-like components of the glomerulus such as the mesangial matrix may have varying glycosaminoglycan composition which may be found in association with glomerular basement membrane fractions.

Animals↗
PubMed1981

The kidney in diabetes.

The kidneys as a target organ for secondary microvascular complications of diabetes mellitus represents a health problem of enormous social cost. Recent studies in man and animals strongly support the concept that the primary responsibility for diabetic nephropathy rests with the metabolic derangements of the diabetic state. However, these metabolic derangements have complex biological effects; it is unlikely that hyperglycemia, per se, produces all of the nephropathic influences of diabetes. Alterations in microvascular hemodynamics in diabetes probably contribute to glomerular pathology. These alterations may be based upon disturbed vasoactive control mechanisms regulating angiotensin and prostaglandin secretion and metabolism. Although much remains to be learned about the pathogenesis of glomerular basement membrane and mesangial thickening in diabetes, these central structural abnormalities appear separable. Mesangial thickening is reversible by cure of the diabetic state in rats whereas glomerular basement membrane thickening is not. Treatment for the diabetic patient with end-stage renal failure has recently improved markedly. Although presently, kidney transplants from living related donors appear best, cadaver transplants and long-term hemodialysis are reasonable options.

Basement Membrane↗
PubMed1981

Malignant osteopetrosis: a disease of abnormal osteoclast proliferation.

Bone biopsies were obtained from two infants with the malignant form of congenital osteopetrosis. Non-decalcified histological sections of each biopsy contained vast numbers of osteoclasts occupying virtually the entire residual marrow space. Despite the apparent failure of normal bone resorption in both patients, the osteoclasts of one appeared histologically and ultrastructurally normal, exhibiting ruffled membrane formation and evidence of acid phosphatase synthesis and secretion. In contrast, the osteoclasts of the second patient were unusually shaped, abnormally large and contained no ruffled membranes. It is concluded that the bone marrow failure which appears in the malignant, as compared to the benign form of osteopetrosis, is at least in part due to replacement of hematopoietic precursors by osteoclasts. Furthermore, the different cytological appearance of the osteoclasts of each patient suggests that a spectrum of pathogenetic mechanisms may be responsible for the development of the disease. Finally, ruffled membrane formation by the osteoclasts of one patient calls into question the assumption that this morphological feature is invariably associated with bone resorption.

Biopsy↗
PubMed1981

Pulmonary inflammation due to oxygen toxicity: involvement of chemotactic factors and polymorphonuclear leukocytes.

Although the pathogenesis of pulmonary oxygen toxicity is not fully understood, the fact that increased numbers of polymorphonuclear leukocytes (PMN) are found in the lung and that these increases coincide with the massive endothelial damage raises the possibility that PMN may contribute to lung injury caused by hyperoxia. In order to begin to elucidate a mechanism for this influx of PMN, we measured the chemoattractant activity for PMN of lung lavages of rats exposed to greater than 95% oxygen for various durations. We found that the chemoattractant activity of the lavages of the lungs of rats exposed to hyperoxia for 66 h was markedly increased (9.66 +/- 1.0 times greater) compared with activities in lavages of normoxic control rats. Furthermore, these increases in chemoattractant activity in lung lavages correlated well with increases in the number of PMN (7 times greater than that in normoxic control animals) in the alveolar lavages that occurred after the rats had been exposed to hyperoxia for 66 h. These increases were followed in a few hours by the death of most of the rats (71%). These findings suggested that a close temporal relationship exists between the generation of high concentrations of chemoattractants in lung lavages, PMN influx into lung lavages, and death of rats exposed to hyperoxia. The results supported the possibility that PMN may be involved in the pathogenesis of pulmonary oxygen toxicity.

Animals↗
PubMed1981

Increased concentration of albumin in kidney basement membranes in diabetes mellitus.

The concentration of albumin was measured by a double-antibody radioimmunoassay in the glomerular basement membrane (GBM) and tubular basement membrane (TBM) of patients with diabetic nephropathy, other kidney diseases, and normal kidneys. The TBM from diabetics contained significantly more albumin (m +/ SD; 2.75 +/- 0.34 microgram/mg) than the TBM from other diseases (1.00 +/- 0.24 microgram/mg) or normals (1.21 +/- 0.26 microgram/mg) (P less than 0.0001). Similarly, diabetic GBM contained more albumin (2.25 +/- 0.59 microgram/mg) than other diseases (1.22 +/- 0.55) or normals (1.31 +/- 0.36 microgram/mg) (P less than 0.01-0.001). No differences were observed between the normal and other disease groups. Although there were no differences in hydroxyproline content, there was a highly significant correlation between the concentration of hydroxyproline and albumin in the diabetic TBM (r = 0.82), diabetic GBM (r = 0.70), and normal TBM (r = 0.79). Elution studies with different buffers on frozen sections of diabetic kidneys suggest that the albumin is relatively firmly bound. Although albumin is present in extracellular membranes of normal and diseased human kidneys, the concentration is higher in diabetes mellitus.

Adolescent↗
PubMed1981

Biochemical abnormalities in osteogenesis imperfecta.

Osteogenesis imperfecta is likely to be caused by primary disorders of synthesis of organic components of connective tissues accounting for clinical and laboratory observations in several affected tissues. Defects in the structure of collagen is well documented in several instances. There is no evidence of a primary disorder in the synthesis of glycosaminoglycans. Several studies of pyrophosphate metabolism and the hormonal control or the overall metabolic activity of isolated cells do not implicate a pathogenic mechanism for this disorder. Detailed biochemical and further clinical correlations are necessary in order to elucidate the pathogenesis of osteogenesis imperfecta.

Bone and Bones↗
PubMed1980

Successful bone-marrow transplantation for infantile malignant osteopetrosis.

A five-month-old girl with autosomal-recessive osteopetrosis received a bone-marrow transplant from her five-year-old HLA-MLC-identical brother after preparation with cyclophosphamide and modified total-body irradiation. Engraftment was documented by chromosomal analysis. Anemia, thrombocytopenia, and leukoerythroblastosis corrected within 12 weeks of transplantation. Low serum calcium and elevated serum alkaline and acid phosphatase levels became normal. Serial x-ray studies revealed bony remodeling and new nonsclerotic bone formation. A pretransplantation bone biopsy revealed small marrow spaces, rare marrow elements, increased osteoclasts, and no bony resorption. After transplantation, osteoclasts were actively resorbing bone, and medullary cavities contained normal bone marrow. Fluorescent Y-body analysis after transplantation revealed donor (male) osteoclasts and recipient (female) osteoblasts. Monocyte bactericidal activity, markedly decreased before transplantation, became normal. Vision, hearing, growth, and development were progressively improving 16 months after transplantation. Allogeneic bone-marrow transplantation appears to be the treatment of choice in this fatal disorder.

Blood Bactericidal Activity↗
PubMed1980

Immune and autoimmune aspects of diabetes mellitus.

The immune and autoimmune aspects of diabetes mellitus are reviewed. Emphasis is given to the clinical association of diabetes with other autoimmune disease; the increased incidence of organ-specific autoimmunity in diabetic patients; the occurrence of humoral and cell-mediated antipancreas (islet) autoimmunity in diabetes; the association of HLA with juvenile-onset, insulin-dependent diabetes mellitus and with certain specific subpopulations of diabetic patients; the possible role of viruses in the etiology of diabetes; and the occurrence of alterations in humoral and cell-mediated immunity, granulocyte function, and the host defense against infectious agents in human diabetics and in animals with experimental diabetes.

Animals↗