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Biomedical subjects

N Green

Publications and source records attributed to N Green.

At least 91 records · Page 5Linked to original sources
PubMed1980

Chemical synthesis of a polypeptide predicted from nucleotide sequence allows detection of a new retroviral gene product.

We previously determined the nucleotide sequence of the 3' end of Moloney leukaemia virus and discovered the potential coding region for an unknown protein, R. We now show that this region does encode a protein. A pentadecapeptide of R was chemically synthesized and antibodies raised against it. Antisera to the synthetic peptide recognize the R protein and the env precursor polyprotein in infected cells. The strategy presented here should provide a general method for accessing proteins predicted by nucleotide sequences.

Amino Acid Sequence↗
PubMed1980

Expression of leukemogenic recombinant viruses associated with a recessive gene in HRS/J mice.

HRS/J inbred mice carry a mutant autosomal recessive gene (hr), which in homozygotes coincides with susceptibility to spontaneous thymic leukemia. Unlike their heterozygote (hr/+) littermates, hr/hr homozygotes express high levels of xenotropic virus during the preleukemic period, and viruses with a broadened host range (termed polytropic viruses) can be isolated from their preleukemic and leukemic tissues. Because hr/hr and hr/+ mice are otherwise genetically identical, the virological differences between them support the role of polytropic viruses in the generation of thymic leukemia. In the present report we show that the HRS/J polytropic viruses are env gene recombinants with unique oligonucleotide and peptide maps. These polytropic viruses appear to arise by recombination between ecotropic virus and an unidentified genome related, but not identical to, the endogenous xenotropic viruses. Moreover, polytropic viruses not only accelerate leukemogenesis in HRS/J mice, but also induce thymic leukemia in the low leukemia strain CBA/J. By contrast, cloned ecotropic and xenotropic viruses have no leukemogenic action.

Animals↗
PubMed1980

The syndrome of multisynostotic osteodysgenesis with long-bone fractures.

Described here are two patients with a newly recognized syndrome of bone and cartilage maldevelopment which, we believe, results from a single embryonic defect, probably of genetic origin. The cardinal manifestations of this association are craniosynostosis, radiohumeral synostosis (RHS), and femoral bowing. Specific secondary defects include midface hypoplasia with characteristic facial appearance and ears, neonatal femoral fractures, and multiple minor anomalies of the limbs. Though the differential diagnosis includes such disorders as the campomelic syndrome, osteogenesis imperfecta (OI) and certain of acrocephalosyndactyly syndromes, the unique combination of clinical and radiographic abnormalities allows ready differentiation. The cause cannot be determined from these two cases.

Bone Diseases, Developmental↗
PubMed1979

Conditioned suppression of a thymus-independent antibody response.

An illness-induced taste aversion was conditioned in mice by pairing cyclophosphamide, an immunosuppressive drug, with the consumption of saccharin, a novel drinking solution. Two weeks after conditioning, animals were injected with the hapten trinitrophenyl (TNP) coupled to the thymus-independent carrier, lipopolysaccharide. Serum antibodies to TNP were titered 6 days later by passive hemagglutination. Relative to control groups, conditioned animals provided with saccharin at the time of antigenic stimulation and, again, 3 days later showed a significant attenuation of their anti-TNP antibody response. In a second experiment, the conditioned stimulus (CS) consisted of the novel saccharin drinking solution plus the noxious internal effects of an injection of LiCl. Conditioned animals reexposed to the CS again showed the lowest antibody titers, but differed significantly from only one of the control groups. Taken together, the results of these experiments confirm previous reports of conditioned immunosuppression and suggest that the effects of conditioning on a primary humoral antibody response can be observed in response to a T-cell independent antigen in the mouse.

Antibody Formation↗
PubMed1979

Rapid staining technique for Trichomonas vaginalis. Preliminary report.

A simple, rapid, staining method for the identification of Trichomonas vaginalis has been tested on cultured trichomonads and specimens of vaginal discharge. Fifty-eight stained slides of vaginal discharge were examined and trichomonads were correctly identified in the 31 specimens from patients with confirmed vaginal trichomoniasis. No false-positive results were obtained. This staining procedure could prove a useful addition to wet-film and cultural methods.

Adolescent↗
PubMed1978

The clinical course and treatment results of patients with postresection locally recurrent lung cancer.

Of 1018 patients with lung cancer seen in the division of radiation therapy between 1963 and 1976, forty-six patients (4.5%) presented with postresection local recurrence and no documented distant metastasis. The median time to recurrence was thirteen months. Most patients had central recurrence with hilar or mediastinal lymph node metastasis, parenchymal consolidation, main stem nodule or bronchial stump tumor. There was a propensity for these tumors to remain limited to the site of origin. Death was most often from local/regional disease rather than distant metastasis. In this clinical setting the effectiveness of radiotherapy was observed in terms of palliation and improved survival. Strong determinants to survival were cell type, tumor dose and tumor response. The median survival was eleven months.

Adenocarcinoma↗
PubMed1977

Effect of dose, time, and ascorbate on iron excretion after subcutaneous desferrioxamine.

The effect of 12 and 24 h continuous subcutaneous infusion of desferrioxamine (D.F.) on urinary iron excretion was compared in 13 patients with beta-thalassaemia major and 1 with congenital sideroblastic anaemia, all of whom were receiving regular blood-transfusions. 750 mg D.F. given over a 12 h period, gave a mean total (30 h) iron excretion of 17-5 mg, which was not statistically different from the mean iron excretion of 21-5 mg when the same dose was delivered over 24 h. 1500 mg D.F. gave a mean urinary iron excretion of 28-1 mg with a 12 h infusion, which was significantly less than the mean iron excretion of 39-6 mg with 24 h infusion. The 1500 mg dose gave a significant increase in iron excretion compared with the 750 mg dose when given by either 12 h or 24 h infusion. 7 of 8 patients, given D.F. over a 12 h period, had increased iron excretion when the dose was increased from 750 to 2000 mg. When the dose was increased to 4000 mg, however, the effect on iron excretion was variable. On the other hand, ascorbic-acid therapy was invariably associated with increased iron excretion after subcutaneous D.F. In twelve studies at different dose levels of D.F., ascorbate therapy was associated with increased iron excretion ranging from 24 to 245%. It is concluded that in most patients with transfusional iron overload subcutaneous D.F over a 12 h period, at a dose ranging from 2 to 4 g daily with ascorbic-acid saturation, is at present the most satisfactory method of removing excess iron.

Administration, Oral↗
PubMed1977

Bicarbonate transport by isolated perfused rabbit proximal convoluted tubules.

Proximal convoluted tubules were dissected from rabbit kidneys and perfused in vitro in order to investigate the relationship between the reabsorption of fluid and of bicarbonate. Bicarbonate was absorbed when it was initially present in the perfusate. At slow rates of perfusion the mean concentration of total CO2 was 9 mM in collected fluid with 25 mM bicarbonate in the bath. At faster rates of perfusion the mean rate of reabsorption was 13.6 pmol cm-1 tubule length s-1. Absorption of bicarbonate was inhibited to a large but not complete extent by elimination of sodium from the perfusate and bath or potassium from the bath, and by addition of ouabain. It was not inhibited by elimination of the organic solutes from the perfusate nor by elimination of chloride from the perfusate and bath. Considered with previous measurements of fluid absorption these results are consistent with the existence of a linked sodium-for-hydrogen ion exchange mechanism at the luminal border of the tubule cells, but there are other possibilities which are discussed. Additionally, the effect of acetazolamide was investigated. The drug virtually completely inhibited bicarbonate absorption and inhibited fluid absorption by 30-40%.

Acetazolamide↗
PubMed1977

Immunological and chromosomal studies in a patient with Sézary syndrome.

A patient with the small-cell variant of Sézary syndrome was studied before and during treatment with low-dose chlorambucil. He had depressed responses to phytohemagglutinin (PHA) and concanavalin A that returned to normal with clinical improvement. Spontaneously dividing cells were found in the peripheral blood by culturing lymphocytes without PHA for 24 hours. Seventy-two-hour PHA-stimulated lymphocyte cultures revealed predominantly hypodiploid chromosome numbers. Both abnormalities improved during treatment. Lymphocytes that were studied for sister chromatid exchanges had an increased number of exchanges per metaphase. Immunofluorescence studies revealed immunoglobulins and C at the dermoepidermal junction and in the dermal vessel walls. Our findings demonstrate that the depression of mitogen responsiveness that is sometimes seen in Sézary syndrome can be favorably affected by chemotherapy. Likewise, some chromosomal abnormalities may regress during successful therapy. These findings may provide a way of measuring the response to therapy.

Chlorambucil↗
PubMed1976

Subcutaneous infusion and intramuscular injection of desferrioxamine in patients with transfusional iron overload.

The effects of intramuscular injection and subcutaneous infusion of desferrioxamine (D.F.) on urinary iron excretion were compared in eleven patients with thalassaemia major and one with congenital sideroblastic anaemia who were being maintained on regular blood-transfusions. Total (48-hour) urinary iron excretion ranged from 3-3 to 40-3 mg (mean 16-3 mg) in nine patients who received 750 mg D.F. intramuscularly before transfusion and from 3-9 to 32-3 mg (mean 11-9 mg) in ten patients who received D.F. by the same route after transfusion. In all 9 patients studied before transfusion, continuous subcutaneous infusion of 750 mg D.F. over 24 hours increased iron excretion by 61-5 to 135-8% (mean 101+/-25-4 S.D.%) compared with intramuscular injection of a similar dose. In the 10 patients studied after transfusion, the iron excretion produced by continuous subcutaneous infusion was from 18-9 to 213% (mean 128+/-74-3%) more than that produced by a single intramuscular injection of D.F. When the subcutaneous dose over 24 hours was increased to 1500 mg in six patients, 48-hour iron excretion ranged from 29-2 to 81-2 mg (mean 52-4 mg) and was increased by 80-2--794% (mean 429%) compared with the excretion when 750 mg was given by intramuscular injection. It is concluded that continuous subcutaneous infusion of D.F. produces more iron excretion in patients with iron overload than intramuscular injection. Providing a suitable portable pump can be carried by the patients, continuous subcutaneous infusion of desferrioxamine may prove a valuable means of preventing or treating iron overload in anaemic patients maintained on regular transfusions.

Adolescent↗
PubMed1976

Role of monovalent ions in the reabsorption of fluid by isolated perfused proximal renal tubules of the rabbit.

Proximal convoluted tubules were dissected from rabbit kidneys and perfused in vitro in order to determine the effect of monovalent ions on fluid absorption and transepithelial voltage. Replacement of sodium in the perfusate and bath by lithium, tetramethyl ammonium or choline caused the rate of fluid absorption and voltage to fall to near zero. Replacement of potassium in the bath by sodium had the identical effect. Replacement of chloride by nitrate or perchlorate had comparatively little effect. The results are consistent with the generally held view that active sodium transport (mediated by a Na- and K- activated adenosine triphosphatase) is the primary process responsible for the absorption of the fluid and the voltage. Replacement of bicarbonate in the perfusate and bath by chloride caused the rate of fluid absorption to decrease by 33%. The possible relation between sodium transport and bicarbonate is discussed.

Animals↗
PubMed1976

Organic solutes in fluid absorption by renal proximal convoluted tubules.

Proximal convoluted tubules were dissected from rabbit kidneys and perfused with artificial solutions in vitro. The effect of various organic solutes on rate of fluid absorption and transepithelial voltage was tested by removing solutes from or adding them to perfusate and/or bath. Omission of albumin from the bath caused rate of fluid absorption to descrease 33% without any change in voltage. Omission of glucose, lactate, alanine, and citrate from the bath had no effect. In contrast, when they were removed from perfusate, rate of fluid absorption fell by 45-75% (depending on whether they were replaced by NaCl or mannitol and NaCl), and voltage (normally negative in lymen) decreased to near zero. Adding glucose or alanine individually to perfusate caused a small increase in rate of fluid absorption and a relatively large increase in voltage. alpha-Methyl-D-glucoside and cycloleucine (which are transported but not metabolized) had effects similar to glucose and alanine, except that voltage changes were not as great. Phlorizin (10(-5) M in perfusate) had the same effect as removing glucose from perfusate. When glucose and alanine were added to perfusate, epithelial cell swelled significantly. Lactate and citrate also caused rate of fluid absorption to increase when they were added to perfusate, but they did not affect transepithelial voltage nor did they cause cells to swell significantly. Possible mechanisms of these effects and the role of organic solutes in fluid absorption by proximal convoluted tubules are discussed.

Alanine↗