Search PubMed⌕ Search

Biomedical subjects

M Smith

Publications and source records attributed to M Smith.

At least 1,279 records · Page 71Linked to original sources
PubMed1979

Prostacyclin: a solution to some problems of extracorporeal circulation. Experiments in greyhounds.

In cardiopulmonary-bypass experiments in greyhounds the effects of adding prostacyclin, prostacyclin plus heparin, and heparin alone to the extracorporeal circulation were compared. With heparin alone platelet count and function were reduced, the pressure differential across the arterial filters rose, platelet deposits were found on the arterial filters, and plasma-fibrinogen levels fell. Plasma from these dogs was toxic to fetal-mouse hearts in culture. With prostacyclin alone, fibrinogen levels fell, but the platelets were preserved. With a combination of prostacyclin and heparin, platelet count and function were maintained, there was no consumption of fibrinogen, and there was little deposition on the arterial filters.

Animals↗
PubMed1979

Multicystic, peritoneal mesothelioma: a report with electron microscopy of a case mimicking intra-abdominal cystic hygroma (lymphangioma).

A 27-year-old Caucasian female complained of persistent, poorly localized abdominal pain of several months' duration, found to be due to a multicystic diffuse lesion involving omentum, peritoneum and pelvic viscera. Three resections were required within a ten-month period for symptomatic control. The tumor showed many of the clinical, operative, gross and light microscopic features of intra-abdominal lymphagioma. Tissues removed at the third operation, however, were examined by electron microscopy, and found to consist of a myriad of small cysts and channels lined by mesothelial cells. In view of these findings, the lesion was regarded as a cystic peritoneal mesothelioma. Similarities between lymphangioma and peritoneal mesothelioma are discussed. It is suggested that electron microscopic examination of lining cells of cystic lesions which are considered grossly consistent with lymphagiomas may yield additional similar cases.

Adult↗
PubMed1979

'Aspira': a new sensitive assay for the detection of hepatitis B surface antigen.

A sensitive method for the detection of hepatitis B surface antigen (HBsAg) is described whereby the separation of specific antibody by affinity chromatography is incorporated into one of the assay reagents. HBsAg, which may be obtained from tissue culture fluids of a human hepatoma cell line, is first reacted with polystyrene beads. Unoccupied spaces on the plastic are next covered with a non-specific protein (e.g. albumin). The plastic is then reacted with either whole antiserum or an IgG fraction of anti-HBs. Care must be taken to cover all of the reacting sites of the first layer of HBsAg with sufficient anti-HBs. This results in a reagent of detecting antigen. No affinity purified antibody was necessary because the reagent, at this stage, contains only specific antibody on the surface. Antigen reacting with this reagent can be detected by the addition of radioactively labeled IgG fraction of anti-HBs, which will complete the 'sandwich'. This assay has been evaluated and found to be as sensitive as those commerically available.

Animals↗
PubMed1979

Structure of the 3' hairpin termini of four rodent parvovirus genomes: nucleotide sequence homology at origins of DNA replication.

The nucleotide sequences of the 3' termini of the DNA from four autonomous rodent parvoviruses have been determined. The terminus of each genome exists as a Y-shaped hairpin structure involving 115 or 116 nucleotides. The sequence of this region of DNA is highly conserved and shows no evidence of internal sequence heterogeneity, a characteristic which is observed in the terminal nucleotide sequence of the helper-dependent, adeno-associated viruses (Berns et al., 1978a). The implications of these results with respect to the models of parvovirus DNA replication are discussed.

Base Sequence↗
PubMed1979

Site-specific mutagenesis using synthetic oligodeoxyribonucleotide primers: I. Optimum conditions and minimum ologodeoxyribonucleotide length.

A synthetic oligodeoxyribonucleotide mismatched at a single nucleotide to a specific complementary site on wild-type circular phi X174 DNA can be used to produce a defined point mutation after in vitro incorporation into closed circular duplex DNA by elongation with DNA polymerase and ligation followed by transfection of Escherichia coli (Hutchison et al., 1978; Gillam et al., 1979). The present study is an investigation of the optimum conditions required for the oligodeoxyribonucleotide-primed reaction for production of transition and transversion mutations in phi X174 DNA, using the large (Klenow) fragment of E. coli DNA polymerase I. Under optimum conditions up to 39% of the progeny of transfection are the desired mutant and significant mutation is observed using a heptadeoxyribonucleotide.

Bacteriophage phi X 174↗
PubMed1979

Site-specific mutagenesis using synthetic oligodeoxyribonucleotide primers: II. In vitro selection of mutant DNA.

A method for the in vitro selection of mutant DNA has been devised as an adjunct to the recently developed method for the use of short enzymatically-synthesized oligodeoxyribonucleotides of defined sequence as site-specific mutagens for circular DNA. The selection method uses the mutating oligodeoxyribonucleotide as a primer for Escherichia coli DNA polymerase I (large fragment) under conditions where there is preferential interaction with mutant DNA template. After ligation using T4 DNA ligase, endonuclease S1 is used to degrade single-stranded non-mutant DNA leaving the desired mutant as closed circular duplex DNA. This paper describes the development of the method using mutants in phi X174 DNA as the model system. Studiies on the changes A leads to G and G leads to A at position 587 of phi X174 viral DNA (am3 to wild-type and its reversal) show that one or two cycles of selection can lead to a population of phage consisting of close to 100% mutants.

Bacteriophage phi X 174↗
PubMed1979

Ultrasonically guided needle biopsy and cytologic diagnosis of solid intraocular tumors.

Six solid intraocular tumors were reliably diagnosed by needle biopsies and cytologic examination of the aspirates. All of the tumors had an unusual clinical or diagnostic feature that raised the possibility of a non-melanomatous tumor. Two intraocular lesions that were obscured by opaque media or a retinal detachment were successfully biopsied under B-scan ultrasonographic guidance of the needle. Cytodiagnosis of narrow spindle B, plump spindle B, and eipthelioid cell types, as well as one case of Coats' disease, was possible and correlated closely with the predominant cell types comprising the lesions discovered on histopathologic examination of the globes that were enucleated. The ocular tissues were not significantly disturbed and hemorrhage was not a serious problem. Details of the biopsy and cytologic techniques, the major clinical indications, for the procedure, and the authors' belief that the procedure is not likely to produce local seeding or extraocular metastasis in cases of melanoma are presented and discussed. Considerable profit may attend the use of this technique for the diagnosis of possible metastatic lesions and tumors of the ciliary body. The technique, however, should not be routinely employed and should be restricted to extremely difficult diagnostic problems.

Adult↗
PubMed1979

Gel electrophoresis of rotavirus RNA derived from six different animal species.

Rotavirus RNA prepared from calf, pig, mouse, deer, foal and dog-adapted human isolates was compared using polyacrylamide gel electrophoresis. Reproducible differences in the RNA migration patterns were found between all isolates. There were 11 clearly resolved segments in the pig, mouse and foal samples. The calf rotavirus RNA and deer rotavirus RNA separated into 9 bands and 10 bands, respectively. The dog-adapted human virus migrated in 12 bands, and this probably results from the complex passage history of the original human rotavirus isolate.

Animals↗
PubMed1979

Site specific endonuclease from Fusobacterium nucleatum.

Four different isolates of Fusobacterium nucleatum (A,C,D and E) contain restriction endonucleases of differing specificity. Whilst many of the endonucleases are isochizomers of known enzymes, two novel activities are Fnu DII which recognizes and cleaves the sequence 5'-CGCT-3'/3'-GCGC-5' AND Fnu EI which recognizes and cleaves the sequence 5'-GATC-3'/3'-CTAG-5' irrespective of the extent of methylation of the adenine residues.

Base Sequence↗
PubMed1979

Rapidly developing tolerance to acute exposures to anesthetic agents.

Following the observation that mice manifest a characteristic withdrawal syndrome after an hour of exposure to nitrous oxide, the authors reasoned that there might be a very rapidly developing tolerance to nitrous oxide. Thus, they determined the inspired concentrations that cause loss of the righting reflex in mice (i.e, the ED50), in the presence of 1 atm of oxygen, of: 1) nitrous oxide alone; 2) cyclopropane alone; 3) nitrous oxide plus 13.6 atm helium; 4) ethylene plus 13.6 atm helium. In each instance the ED50 was determined after averages of 6,34 and 64 min of exposure to the anesthetic agents. For nitrous oxide alone the ED50 at 6 min was 1.18 +/- 0.049 atm, increasing to 1.39 +/- 0.061 atm at 64 min. For ethylene plus helium the ED50 increased from 1.21 +/- 0.033 atm at 6 min to 1.31 +/- 0.039 atm at 64 min, indicating the development of acute tolerance. Neither cyclopropane alone nor nitrous oxide plus helium caused acute tolerance. This absence of tolerance may have resulted from a slower development of an alveolar anesthetic concentration.

Anesthetics↗
PubMed1979

Transcription of the Marek's disease virus genome in virus-induced tumors.

Transcription of the Marek's disease virus (MDV) genome in tumor tissues from MDV-infected chickens has been studied by analyzing the hybridization kinetics of (3)H-labeled MDV DNA with unlabeled RNA extracted from these tissues. Lymphoid tumors of ovary, spleen, liver, and kidney contained MDV genomes, but the virus-specific RNA sequences were transcribed from less than 15% of the viral DNA. A virus nonproductive lymphoblastoid cell line, designated MKT-1, has been established from a kidney lymphoma and contains 15 MDV genomes per cell. In these cells, 12 to 14% of the viral DNA was transcribed. Thus transcription of the MDV genome was restricted both in tumor tissues and MKT-1 cells. A hybridization experiment where RNA extracted from MKT-1 cells and RNA extracted from a spleen tumor were mixed and hybridized to (3)H-labeled MDV DNA indicated that the virus-specific RNAs from the two sources were encoded by the same DNA sequences. The polyribosomal fractions of MKT-1 cells and this spleen tumor contained only a portion of the virus-specific RNA sequences found in whole-cell extracts, indicating the existence of a posttranscriptional control mechanism which prevents the transfer of certain viral RNA transcripts to the polyribosomes. The data suggest that the repressed expression of the viral genome in lymphoid tumor tissues and MKT-1 cells may be the result of precise controls within the cell at the transcriptional and posttranscriptional levels.

Animals↗