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Biomedical subjects

D Spector

Publications and source records attributed to D Spector.

At least 55 records · Page 3Linked to original sources
PubMed1983

Isolation and partial characterization of dinoflagellate U1-U6 small RNAs homologous to rat U small nuclear RNAs.

The dinoflagellates are a group of diverse eukaryotic algae possessing a number of unique cellular properties. Evidence is presented for the presence of six capped small nuclear RNAs in these dinoflagellates. By several criteria such as the (a) presence of trimethylguanosine cap structure in U1 to U5 RNAs, (b) sequence homology between rat and dinoflagellate U2, U5 and U6 RNAs, (c) presence of other post-transcriptional modifications such as sugar and base modifications, and (d) association of Sm antigen with five of these six RNAs, the six RNAs of dinoflagellates appear to be similar to the well characterized U1 to U6 RNAs found in higher eukaryotes. This is the first demonstration of antigenic small nuclear RNA-containing particles in any unicellular organism. These results suggest that the U1 to U6 RNAs and the associated Sm antigen evolved at a very early stage of eukaryotic evolution. With respect to U small nuclear RNAs and their associated proteins, the dinoflagellates appear to exhibit eukaryotic characteristics.

Animals↗
PubMed1983

tRNA-rRNA sequence homologies: evidence for a common evolutionary origin?

Many tRNAs of E. coli and yeast contain stretches whose base sequences are similar to those found in their respective rRNAs. The matches are too frequent and extensive to be attributed to coincidence. They are distributed without discernible pattern along and among the RNAs and between the two species. They occur in loops as well as in stems, among both conserved and non-conserved regions. Their distributions suggest that they reflect common ancestral origins rather than common functions, and that they represent true homologies.

Base Sequence↗
PubMed1983

A controlled study of the effect of indomethacin in uremic pericarditis.

To determine the impact of indomethacin on the course of uremic pericarditis we performed a prospective, double blind study in which 24 patients with endstage chronic renal failure and pericarditis randomly received indomethacin, 25 mg four times daily, (11 patients) or a placebo (13 patients) for a 3-week period. All patients received peritoneal or hemodialysis treatment concurrently with the study drug. In contrast to the placebo, indomethacin produced an immediate and sustained reduction of fever in all but one patient. On the other hand, indomethacin had no effect on the duration of chest pain (mean days +/- SE: placebo 1.4 +/- 0.6, indomethacin 5.5 +/- 3.3), duration of pericardial friction rub (placebo 10.3 +/- 1.7, indomethacin 16.0 +/- 3.8), or on the amount of pericardial effusion. Further, indomethacin did not diminish the need for invasive surgical procedures for relief of tamponade (three of 13 placebo patients, two of 11 indomethacin patients) or result in decreased mortality rate. Death (not due to pericarditis) occurred in two patients treated with indomethacin and one patient who received the placebo. In our patients pericarditis encompassed a wide spectrum ranging from a mild illness of several days duration to a painful and debilitating disease lasting weeks and requiring surgical intervention. Although the size of our population prohibits definitive conclusions, it would appear that, except for fever, the manifestations and natural history of this illness are unaffected by indomethacin.

Adult↗
PubMed1979

Heterogeneity of genetic loci in chickens: analysis of endogenous viral and nonviral genes by cleavage of DNA with restriction endonucleases.

Restriction endonucleases can be used to define the structure and position of genetic loci for which specific molecular hybridization reagents are available. We have used this approach to compare 18 chicken embryos with respect to several cellular genes; endogenous viral DNA related to the replicative genes of avian sarcoma virus (ASV) or to RAV-O, an endogenous virus of chickens; and sequences related to the transforming (src) gene of ASV. Each cellular gene eas remarkably homogeneous within our test population. We found little or no variation in globin and ovomucoid genes; ovalbumin and transferrin (with one exception) showed variation which is probably allelic in nature. The endogenous viral DNA which has homology with RAV-O was found at several different positions in host DNA and its structure resembled that of proviruses acquired by experimental infection, with sequences from both ends of viral RNA repeated near both ends of viral DNA. Within the population of 18 chickens, one endogenous provirus was always present, whereas the several other proviruses were each found in only a few members of this group. However, screening of additional chickens identified individuals lacking the provirus common to the initial 18 animals surveyed; in at least one embryo no RAV-O-related DNA was detected. These findings suggest that the endogenous RAV-O-related sequences have entered the germ line by relatively recent infection and are still segregating in several contemporary chicken flocks. The sequences in the chicken genome which have homology with the src gene of ASV are invariant from bird to bird and in this sense resemble a cellular gene rather than a viral sequence.

Alpharetrovirus↗
PubMed1979

Gene localization by chromosome fractionation: globin genes are on at least two chromosomes and three estrogen-inducible genes are on three chromosomes.

Chicken metaphase chromosomes were partially purified by rate zonal centrifugation, and DNA was prepared from each of the fractions of the sucrose gradient. The DNA was digested with various restriction enzymes and subjected to electrophoresis in agarose gels. The DNA was transferred to nitrocellulose filters (as described by Southern), and the filters were hybridized with cDNA probes. Four globin genes alpha A, alpha D, beta, and rho or epsilon are located on at least two chromosomes, and three of the estrogen-inducible genes of the hen oviduct--ovalbumin, ovomucoid, and transferrin--are on three different chromosomes. These experiments also confirm our earlier assignment of the endogenous viral sequence related to Rous-associated virus-0 to a separate (and larger) chromosome than the cellular sequence related to the transforming gene of avian sarcoma virus (cellular sarc), although it now appears that cellular sarc is on a small macrochromosome, rather than on a microchromosome.

Animals↗
PubMed1979

Modulation of herpes simplex virus replication in adenovirus transformed cells.

The ability of herpes simplex virus 1 to replicate in cells transformed by adenovirus type 5 is strongly dependent on the origin of the cells. Studies show that adenovirus transformed rat cells lose their permissiveness while cells of hamster or human origin retain their ability to replicate HSV although at a reduced level when compared to the untransformed parent cells. One line of adenovirus transformed rat cells, 107, demonstrates thermosensitive events, allowing HSV to replicate at 34 degrees C but not at 37 degrees C. Analysis of the biochemical events taking place at 37 degrees C showed that virus-specific DNA synthesis was greatly reduced but that all of the late virus structural proteins could be observed after SDS-polyacrylamide gel electrophoresis. It was also demonstrated that shut-off of host macromolecular synthesis appeared to be less efficient after HSV infection of 107 cells than after infection of more permissive cells such as the non-transformed REF line. Collectively the data show that interactions between HSV and the host cell are perturbed when the cell is transformed by type 5 adenovirus. The degree of perturbation ranges from a slight reduction in number of progeny to a completely abortive infection.

Adenoviridae↗
PubMed1978

Painful crises following renal transplantation in sickle cell anemia.

A 34 year old woman with sickle cell (SS) anemia and chronic renal failure of unknown etiology was maintained on dialysis for 11 months before she received a cadaveric renal transplant. After 24 months, transplant function is excellent although a mild urinary concentrating defect (Umax = 532 mOsm/liter) is present. Renal biopsies five and 11 months after transplant revealed mild focal interstitial infiltrates and mesangial thickening. A major complication has been the reemergence of numerous severe painful crises, inferred to be caused by an increased blood viscosity consequent to a rising hematocrit value, after a hiatus of many years. The succession of crises was stopped with a prophylactic partial exchange transfusion program, reemerged when the program was discontinued, and was stopped again when the transfusion program was reinstituted. We conclude that renal transplantation may be successfully performed in patients with sickle cell disease. Complications of the hemoglobinopathy may develop, but painful crises can be successfully managed with judicious transfusion therapy.

Adult↗
PubMed1978

Herpesvirus infection modifies adenovirus RNA metabolism in adenovirus type 5-transformed cells.

The effect of herpes simplex virus (HSV) infection of mRNA metabolism was examined in a system where the fate of specific RNA sequence can be assayed. Adenovirus type 5-transformed rat embryo cell line 107 synthesizes adenovirus-specific RNA (ad-RNA), which functions in the cytoplasm as mRNA. We have utilized ad-RNA as a model for mRNA metabolism, and in a preliminiary study we characterized ad-RNA in the nucleus and cytoplasm by hybridization to filter-bound adenovirus DNA. The results indicated the as-RNA accumulates in the nucleus and that cytoplasmic polyadenylic acid [poly(A)]-containing ad-RNA turns over with a half-life of a few hours. Pulse-chase experiments confirmed these observations and a half-life of about h was determined for the poly(A)-containing cytoplasmic ad-RNA. A second class of ad-RNA remains in the nucleus, where it turns over with a longer hlaf-life (about 24 h). The infection of 107 cells by HSV was restricted at 37 degree C, giving a burst size of 5 PFU per cell and allowing continued host DNA synthesis. Protein synthesis was inhibited greater than 50% by 7 h after infection, and total RNA synthesis was 50% inhibited by 4 h after infection. During the first 8 h after infection, HSV has little effect on the rate of synthesis of ad-RNA as determined by hybridization of nuclear RNA samples, but,during the same period, HSV inhibits the accumulation of poly(A)-containing ad-RNA in the cytoplasm. The degree of this inhibition increases steadily throughout this period and reaches 60% by 6.5 to 8 h after infection. Nosignificant effect was seen on the accumulation of total cellular poly(A)-containing RNA. It was concluded from these experiments that HSV infection alters the metabolism of ad-RNA so as to prevent the normal appearance of the poly(A)-containing mRNA in the cytoplasm. The result for ad-RNA may not represent the behavior of total cellular poly(A)-containing RNA under conditions where infection is restricted.

Adenoviridae↗
PubMed1978

Fatal paraquat poisoning: tissue concentrations and implications for treatment.

A 27-year-old male died 30 1/2 hours following ingestion of paraquat. Hemodialysis removed 72 mg of paraquat, which represented only 2% of the calculated absorbed dose; paraquat concentrations were determined in post-mortem tissue and were high in the lungs and kidneys. Prominent histologic changes were already present in the lungs, which showed extensive evidence of alveolar injury, and in the adrenal gland, which showed massive selective necrosis of the zonae fasciculata and reticularis. These findings emphasize the inadequacy of treatment regimens that attempt only to remove paraquat from body tissues. Trials of treatments designed to prevent gastrointestinal absorption, including combinations of absorbents, cathartics and gut lavage, are warranted.

Adrenal Glands↗
PubMed1977

Messenger RNA for myosin polypeptides: isolation from single myogenic cell cultures.

Messenger RNA which stimilates the synthesis of myosin heavy chain in a reticulocyte lysate has been isolated from single myogenic cell cultures. Specific myosin polypeptides have been identified by immunoprecipitation with an antibody made to purified adult chicken skeletal muscle myosin. This mRNA binds to oligo(dT)-cellulose, and an active fraction from sucrose gradients migrates as 26S on formamide-polyacrylamide gels. The relative amount of this RNA increases dramatically at the time of terminal differentiation.

Cell Differentiation↗
PubMed1977

Histologic changes in preserved cadaveric renal transplants.

The histologic changes in human cadaveric kidneys preserved by either simple hypothermia or continuous pulsatile perfusion were studied by light and electron microscopy and by immunofluorescence in biopsies obtained immediately before (15 kidneys) and approximately 1 hour after (41 kidneys) transplantation. The changes observed in pretransplantation biopsies were largely similar in kidneys preserved by either method with the exception that foreign material was found in the vasculature of perfused kidneys only. Endothelial edema was more frequent and more severe in nonperfused kidneys only. Endothelial edema was more frequent and more severe in nonperfused kidneys. In the 1 hour posttransplantation biopsies, a lesion resembling intravascular coagulation (IVC) was noted in 18 of the 25 perfused kidneys but was absent from all 16 nonperfused kidneys. Transplants with severe IVC lesions failed to function and had extensive cortical necrosis when removed by the end of the first month. In follow-up biopsies, milder lesions appeared to heal fast and were compatible with transplant function. The IVC lesion is probably due to endothelial cell damage during perfusion of the kidneys.

Biopsy↗
PubMed1977

Hepatitis B miniepidemic in a peritoneal dialysis unit.

Two staff nurses in a peritoneal dialysis unit developed type B viral hepatitis while caring for a patient with persistent Hb Ag antigenemia. Peritoneal dialysis fluid from the patient contained surface Hb Ag antigen and was the probable mediator of the viral transfer. Hb Ag testing should be routine in peritoneal dialysis programs, and special precautions should be taken with dialysate of patients affilcted with hepatitis and/or Hb Ag antigenemia.

Adult↗
PubMed1976

Perfusion nephropathy in human transplants.

To determine whether perfusion preservation affected the structure and survival of kidney transplants, we correlated clinical and histologic data in 77 kidneys biopsied one hour after transplantation. Twenty-one of 36 perfusion-preserved kidneys had a glomerular capillary lesion suggestive of intravascular coagulation. None of 41 kidneys preserved by hypothermia alone had this lesion. Presence of the lesion did not correlate with donor or recipient characteristics, warm or cold ischemia time, HLA match, percentage of preformed lymphocytotoxic antibody titers or perfusion characteristics. Of 21 transplants with the lesion, nine required nephrectomy by one month, and one-month serum creatinine was less than 2.0 mg per deciliter in only three of the remaining 12 transplants. We conclude that perfusion preservation may cause pathologic changes that may adversely affect kidney-transplant function. The causes of the pathologic process remain unclear.

Cadaver↗
PubMed1973

The effect of chronic sodium loading and sodium restriction on plasma prostaglandin A, E, and F concentrations in normal humans.

It has been suggested that prostaglandins may be involved in the control of sodium homeostasis. Prostaglandin A and prostaglandin E have been shown to increase renal blood flow and urinary sodium excretion and prostaglandin A has been shown to stimulate aldosterone release. The purpose of this study was to determine the effect of chronic sodium loading and sodium restriction on plasma prostaglandin A, E, and F concentrations. SEVEN NORMAL HUMAN VOLUNTEERS WERE PLACED ON THREE SODIUM INTAKE DIETS: (a) ad lib. sodium intake, (b) high sodium intake, and (c) low sodium intake. Plasma prostaglandin A, E, and F concentrations were measured by radioimmunoassay. Mean prostaglandin A levels on the ad lib. diet were 1.60 ng/ml. Prostaglandin A levels decreased 49% to 0.82 ng/ml on the high sodium intake and increased 34% to 2.14 ng/ml on the low sodium intake. Prostaglandin A levels increased 161% on the low sodium diet in comparison with levels on the high sodium diet. Plasma prostaglandin E and F concentrations did not change significantly during variation in sodium intake. These results show that dietary sodium content markedly effects plasma prostaglandin A levels and that prostaglandins may play a role in the physiologic mechanism of sodium homeostasis.

Adult↗