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PubMed1977

Prospects of three-dimensional high resolution electron microscopy of non-periodic structures.

In the first part of the paper the general features of three-dimensional electron microscopy of non-periodic structures at high resolution are discussed. Such an analysis requires series of 20 or more exposures of mechanically moved specimens. It is fundamentally important that the integral radiation dose, however, need not be increased--three-dimensional analysis yields extra information without additional radiation loading. It is demonstrated that the constraints characteristic for atomic resolution can in future facilitate many difficulties like restricted tilting range (conical tilting), inaccuracies in the refinement of the origin determination etc. Data collection up to atomic resolution is possible with existing image reconstruction methods if the chromatic spread of the cathodes can be partially corrected. The relatively great radiation induced changes of "stable" specimens will require additional averaging in the experiment (quasi-simultaneous registration). The advantage of a time dependent analysis of radiation sensitive structures--especially the possibility of using redundancies in the analysis (trace structure analysis)--is discussed. The experimental part (studies of radiation damage and three-dimensional work on carbon foils) presents examples of such analyses. The main experimental difficulty consists in the collection of many exposures with no extra load of the specimen in the intervals between exposures.

Carbon↗
PubMed1977

The effect of bite plane use on terminal hinge axis location.

The effect of bite phase therapy on the location of hinge axis was observed and compared in a sample of normal subjects and a group of individuals with TMJ dysfunction. The normal group displayed a mean change of 1.0 mm with a range of 0.3 mm to 3.4 mm between bite plane use and its absence. The direction of change with bite plane use was anterior with a tendency for superior component. The same group utilized the bite plane a second time and the axis location was compared with the original determined with bite plane use. This procedure was done to test the reproducibility of hinge axis on normal subjects. The mean change between the two bite plane uses was .87 mm with a range of 0.0 mm to 3.0 mm. The symptomatic patients changed a mean of 1.46 mm with a range of 0.0 to 3.3 mm. The direction of change was definitely posterior following therapy with a strong tendency for a superior component. This study seems to emphasize the need for a relaxed and asymptomatic muscular pattern for individuals on whom occlusal adjustments are to be made. In the presence of erroneous maxillomandibular skeletal relationships inaccuracy is inherent for occlusal equilibration.

Adolescent↗
PubMed2025

Methylation-based droplet digital polymerase chain reaction shows high concordance with chronic lymphocytic leukemia IGHV somatic mutation status.

OBJECTIVE: Somatic hypermutation at immunoglobulin heavy chain variable (IGHV) genes, an established prognostic and predictive biomarker for chronic lymphocytic leukemia (CLL), is assessed by gene sequencing. We developed a single methylation-specific droplet digital polymerase chain reaction (methyl-ddPCR) to predict IGHV status in patients with CLL. METHODS: The CLL methylation array and IGHV data from the International Cancer Genome Consortium (ICGC) were used for biomarker discovery. Top-ranked candidate regions were manually screened for PCR primer and probe binding sites. A single methyl-ddPCR was evaluated on an internal cohort of CLLs with mutated (M), unmutated (U), and inconclusive IGHV results originally determined by next-generation sequencing (NGS). RESULTS: Analysis of ICGC data identified array probe cg23844018 as a candidate for the PCR. The corresponding CpG site showed high methylation levels in U-CLL and lower levels in M-CLL. On the internal cohort, a single optimal cutoff correctly classified 104 of 115 U- and M-CLLs (90.4%; area under the curve = 0.96). The PCR data correlated with some prognostic fluorescence in situ hybridization and CLL subset groupings. Limited analysis suggests that the PCR may be able to stratify some patients with CLL who have inconclusive results on IGHV NGS testing. CONCLUSIONS: The methyl-ddPCR showed high concordance with CLL IGHV status in an internal cohort.

Humans↗
PubMed1991

Mutants affecting processing of DNA in macronuclear development in paramecium.

In Paramecium tetraurelia, stock 51, the A surface protein is coded by the wild type A51 gene, present in micronuclei in two copies and in macronuclei in about 1500 copies. DNA processing, comprised of DNA cleavage, copy number amplification and telomere addition occurs at autogamy and conjugation when old macronuclei degrade and new macronuclei are formed from micronuclei. In this paper we characterize mutants with macronuclear A gene deletions. These mutants are notable in three respects. First, the mutants do not appear to be simple micronuclear deletions. Although genetic analysis shows that the d12 mutant d12(-1300) is homozygous for the allele A-1300 and the mutant d12(+1) for A+1, analysis by the polymerase chain reaction indicates that the micronuclei in these two mutants contain intact, but presumably altered, micronuclear A genes. They undergo deletion during DNA processing when new macronuclei are formed. Second, the position of the deletions in these alleles has been shown to change. The deficiency present in the d12 allele A-1300 was originally determined to extend from position -1300 (relative to the start of translation of the A gene) to the end of the chromosome. Later, a derivative of this strain, homozygous for the d12 allele A+1 was isolated in which the start site of the deletion was found to have moved from -1300 to +1. Third, a surprising interaction occurs in crosses between a line homozygous for the d12 allele and one homozygous for the wild-type A51 allele. Previous work on the non-Mendelian d48 mutant (which has intact A51 genes in its micronucleus, but has truncated A51 genes in its macronucleus) has shown that intact A51 alleles must be present in the old macronucleus in order for A51 alleles to undergo proper processing. We find that d12 alleles act on A51 alleles in heterozygotes such that intact macronuclear A genes are no longer required for proper processing of A51. Thus, in crosses of 51 x d12 (either +1 or -1300) d12 exconjugants, as well as 51 exconjugants, give rise to clones carrying both intact A51 and truncated d12 alleles. Remarkably the d12 alleles, which are themselves deleted during processing, are capable in the heterozygote of fostering normal processing of the A51 allele.

Animals↗
PubMed1985

Persistence of host Langerhans cells following allogeneic bone marrow transplantation: possible relationship with acute graft-versus-host disease.

Langerhans cells (LC) are bone marrow-derived dendritic antigen-presenting cells found in the epidermis. In an effort to determine the origin (host versus donor) of LC at different intervals following bone marrow transplantation, we performed skin biopsies in 16 recipients of sex-mismatched marrow. LC were identified using monoclonal antibody OKT6 in an indirect immunoperoxidase assay and their donor or host origin determined according to the presence or absence of Y body. The presence of Y-positive (donor) LC could be demonstrated in all (6/6) skin biopsies of female recipients of male marrow tested between days 39 and 730 post-transplant. Persistence of host LC in male recipients of female marrow was documented in all (6/6) recipients studied on day 39 and in two out of seven patients tested on day 120 post-transplant. From day 365 onward, no residual host LC could be detected, suggesting that by this time all epidermal LC are donor-derived. Our study demonstrates that host LC usually persist for 39 and up to 120 d following bone marrow transplantation. The relevance of this observation to the possible role of LC and other host dendritic antigen-presenting cells in the graft-versus-host reaction is discussed.

Acute Disease↗
PubMedDate not supplied

Diabetes in the UK West indian community: the Wolverhampton survey.

A survey was carried out to determine the prevalence of known diabetes amongst West Indians living in Wolverhampton. Two hundred and fifty-one West Indians with diabetes were identified from a computerized register, which records all diabetic patients in the Wolverhampton area attending either the hospital diabetic clinic or general practitioner mini-clinics, and from questionnaire data obtained through local general practitioners. An estimated 4.4% of the Wolverhampton population are of West Indian origin determined by the 1981 census, giving a prevalence of known diabetes of 2.2% compared with 1.2% in the indigenous UK white Caucasian population. Only 4% of these patients were truly insulin-dependent but 38% were insulin-treated, 43% were on oral hypoglycaemic agents and 19% on diet alone. Only 1.6% were diagnosed below the age of 20 years, with peak frequency of diabetes occurring in the age group 45-64 years. Thirty-eight percent of all patients were obese, 40% were hypertensive, but only 4% had a history of angina or myocardial infarction. In UK West Indians non-insulin-dependent diabetes is common and is predominantly a disease of middle age, whereas insulin-dependent diabetes is relatively uncommon.

Age Factors↗
PubMed1985

Immunoassay of the neuronal and neuroendocrine marker PGP 9.5 in human tissues.

An inhibitory, coated-well immunoassay for the neurone-specific protein PGP 9.5 has been devised and used to measure the concentrations of the protein in human tissues. Concentrations of PGP 9.5 between 40 ng/ml and 10 micrograms/ml could be measured using this assay. In brain PGP 9.5 was present at 100.58 +/- 16.18 micrograms/mg protein. Of the other organs examined only kidney and testis showed significant concentrations of PGP 9.5 (3.97 +/- 0.87 microgram/mg protein and 3.25 +/- 0.36 microgram/mg protein, respectively). All other organs contained less than 2% of the brain level. The tissue levels determined by coated-well immunoassay confirmed the tissue specificity of PGP 9.5 originally determined by high-resolution two-dimensional gel electrophoresis.

APUD Cells↗
PubMed1979

Conserved region of mammalian retrovirus RNA.

The viral RNAs of various mammalian retroviruses contain highly conserved sequences close to their 3' ends. This was demonstrated by interviral molecular hybridization between fractionated viral complementary DNA (cDNA) and RNA. cDNA near the 3' end (cDNA(3')) from a rat virus (RPL strain) was fractionated by size and mixed with mouse virus RNA (Rauscher leukemia virus). No hybridization occurred with total cDNA (cDNA(total)), in agreement with previous results, but a cross-reacting sequence was found with the fractionated cDNA(3'). The sequences between 50 to 400 nucleotides from the 3' terminus of heteropolymeric RNA were most hybridizable. The rat viral cDNA(3') hybridized with mouse virus RNA more extensively than with RNA of remotely related retroviruses. The related viral sequence of the rodent viruses (mouse and rat) showed as much divergence in heteroduplex thermal denaturation profiles as did the unique sequence DNA of these two rodents. This suggests that over a period of time, rodent viruses have preserved a sequence with changes correlated to phylogenetic distance of hosts. The cross-reacting sequence of replication-competent retroviruses was conserved even in the genome of the replication-defective sarcoma virus and was also located in these genomes near the 3' end of 30S RNA. A fraction of RD114 cDNA(3'), corresponding to the conserved region, cross-hybridized extensively with RNA of a baboon endogenous virus (M7). Fractions of similar size prepared from cDNA(3') of MPMV, a primate type D virus, hybridized with M7 RNA to a lesser extent. Hybridization was not observed between Mason-Pfizer monkey virus and M7 if total cDNA's were incubated with viral RNAs. The degree of cross-reaction of the shared sequence appeared to be influenced by viral ancestral relatedness and host cell phylogenetic relationships. Thus, the strikingly high extent of cross-reaction at the conserved region between rodent viruses and simian sarcoma virus and between baboon virus and RD114 virus may reflect ancestral relatedness of the viruses. Slight cross-reaction at the site between type B and C viruses of rodents (mouse mammary tumor virus and RPL virus, 58-2T) or type C and D viruses of primates (M7, RD114, and Mason-Pfizer monkey virus) may have arisen at the conserved region through a mechanism that depends more on the phylogenetic relatedness of the host cells than on the viral type or origin. Determining the sequence of the conserved region may help elucidate this mechanism. The conserved sequences in retroviruses described here may be an important functional unit for the life cycle of many retroviruses.

Animals↗
PubMed1978

Acid- and alkaline phosphatase in amniotic fluid in normal and complicated pregnancy.

171 samples of amniotic fluid were obtained by abdominal amniocentesis from 67 women with complicated pregnancies (isoimmunization, diabetes mellitus or toxaemia). The levels of heat-labile alkaline phosphatase (HLAP), heat-stable alkaline phosphatase (HSAP) and acid phosphatase (AcP) were determined and compared to the enzyme levels in 179 samples from women with normal pregnancies of corresponding gestational ages. HLAP showed two "peaks" of activity, one in the 5th-22nd week and the other at term. HSAP and AcP showed increased activity at term. HSAP was decreased (p less than 0.01) in isoimmunization between the 36th and 40th week. 11 cases of toxaemia with placental insufficiency showed no differences in the levels of HLAP and HSAP compared with normal pregnancy. AcP showed no differences between normal and complicated pregnancy. Samples contaminated by blood showed no significant increase in the acid- and alkaline phosphatase levels. Samples contaminated by meconium showed a complex pattern. Some samples had normal enzyme levels, some had high levels of HLAP only and some had high levels of HSAP and AcP. The origin of the enzymes is not known with certainty. HSAP in amniotic fluid is most likely not of placental but intestinal origin. Determinations of acid- and alkaline phosphatase in amniotic fluid seem to be of little values in the clinical management of complicated pregnancy.

Acid Phosphatase↗
PubMed1988

Pursuit and saccadic eye movements in response to unpredictable constant velocity targets.

Pursuit eye movements in response to unpredictable reversals of constant velocity target motion at 20 degrees, 40 degrees and 60 degrees/s were analysed in 20 normal subjects. The gain in smooth pursuit was originally determined by the preceding target duration; the shorter the preceding movement, the longer was the acceleration of pursuit velocity inhibited. The ongoing target duration secondarily affected the gain at faster target velocities by restricting time for eye velocity acceleration. Whereas the saccadic reaction time was around 200 ms, the intersaccadic interval shortened as target velocity increased. The saccadic amplitude increased in direct proportion to an increase in target velocity. The present study showed that, even under irregular stimulations, pursuit eye movement is regulated in a feedforward manner by the perceptual analysis of the preceding target motion, and that corrective saccades in pursuit eye movement correspond to those observed in step displacements, except for the programming on the basis of the changing rate of position error.

Adult↗
PubMedDate not supplied

A practical approach to coma diagnosis in the unresponsive patient.

Diagnosis of coma in the unresponsive patient can be done in a relatively short time by making key observations that will confirm disease of either the brain stem or the hemispheres, the two locations in which coma originates. Determining the location of the lesion is the primary goal in early assessment of the unresponsive patient. Examination of the patient's eyes is the single most important step in understanding coma.

Brain Stem↗
PubMed1975

Rejection and repair of endothelium in major vessel transplants.

Fresh saphenous vein homografts are gaining popularity as conduits for femoral-popliteal or distal bypass grafts. Aside from major blood group compatibility, there is little clinical evidence that rejection is a significant factor in long-term patency. Some have suggested that blood vessels are weakly antigenic and others indicate that rejection does not endanger long-term patency. Transplantation and toxic damage were produced in experimental animals in order to compare healing processes. Both types of injuries produced early significant endothelial cell proliferation detected by H3-thymidine uptake. This response peaked at 5 days in transplants and ever-expanding islands of proliferating endothelium were present in aortas exposed to 20 percent sodium chloride, leading to healing in 3 to 4 months. In the transplanted vessels, total endothelial destruction occurred at 11 to 28 days, and cells of host origin determined by sex chromatin analysis gradually resurfaced those grafts that maintained patency. At 4 months only two of six carotid artery homografts were patent in unmodified dogs, and eight of nine were patent in animals given 1 mg. per kilogram of Imuran. All patent grafts were resurfaced by host cells. We conclude that rejection does play a role in long-term patency; that donor endothelium of living vascular grafts cannot maintain sufficient proliferative capacity to repair immunological damage; that small doses of Imuran significantly alter the rate of destruction leading to more orderly repair and patency; and that clinical trials utilizing one half the dose of Imuran required for kidney graft survival are likely to improve significantly the long-term patency rate of fresh arterial or venous homografts in man.

Animals↗
PubMed1989

Biological determinants in implant design.

This paper considers whether fibro-osseous integration is a feasible outcome for dental implants and whether the mucosal-implant junction is a crucial factor for implant success. It is argued that the periodontal ligament is a connective tissue with specific origin determined early in development. Further, it is argued that fibroblasts of the ligament exhibit unique functional characteristics associated with tooth support and that these characteristics cannot, as yet, be duplicated in other fibroblasts. These specific attributes argue against the feasibility of fibro-osseous integration unless cells of the periodontal ligament are available to develop a fibrous attachment. With respect to the dentogingival junction, it is argued that this structure does not provide a functional seal around the normally functioning tooth and therefore a minor degree of inflammation in the connective tissue adjacent to an implant is acceptable. It is also argued that inflammation associated with fibro-osseous integrated implants is not the result of a deficiency in the epithelial attachment but rather is due to the inability of the connective tissue to withstand the forces applied to it.

Dental Implantation, Endosseous↗
PubMed1989

[Glass ionomers--types and clinical application].

With the formation of the glassionomers one wanted to combine the major qualities of the silicate cement, the composite resins and the polycarboxylate cement. The greatest advantages are bonding to tooth structure, the release of fluorides and thereby an inhibition of secondary caries, and a thermal coefficient similar to tooth structure. The glassionomers are more compatible to the pulp than the old silicates. The bonding to tooth structure is increased through pretreatment where polyacrylic acid is most recommendable. Today there are two major types of glassionomers: the water-based which contain freeze-dried acid in the glass powder, and the original, determined by the addition of an aqueous solution of polyacrylic acid to the glass powder. Certain types are delivered in premeasured capsules for mechanical blend, which decreases the sensitive handling of the material. The use of glassionomers serves a number of purposes and will properly be more widespread in the future, especially the concern of lining in combination with composite resins, the metal-reinforced to crown-buildup and the luting types, when the considerations about earlier hypersensitivity after luting of castings is clarified. The restorative types shows better promising results than composite resins in Class V restoration.

Dental Bonding↗
PubMedDate not supplied

Influence of dietary calcium stress on lethality of avian influenza viruses for laying chickens.

The effect of calcium stress was studied in an attempt to reproduce lethal infections in laying chickens with A/Chicken/Alabama/75 (H4N8) influenza virus and with two nonpathogenic H5N2 influenza viruses from the 1983-84 outbreak in the eastern United States. Hens were fed calcium-deficient or standard diets for 7 to 14 days; then the calcium-deficient feed was replaced with standard feed supplemented with ad libitum oyster shell, and both groups of hens were inoculated with virus. When hens were infected with the H4N8 virus, respective mortalities of those on the calcium-deficient and standard diets were 19% (27/141) and 5% (7/143). The H5N2 viruses did not kill hens fed either diet. In standard pathogenicity tests, Alabama H4N8 viruses reisolated from the hens that died generally were more lethal for 4-week-old chickens than the stock virus. These results argue for characterization of the Alabama H4N8 virus as pathogenic rather than nonpathogenic as originally determined.

Animals↗
PubMed1988

Pesticide residue control in the years 1980-1982.

Data on pesticide residue on vegetables, fruits, cereals, and other foods of vegetable or animal origin determined by Provincial Laboratories during the years 1980-1982 are presented and compared with levels permitted by Italian legislation. An analysis of the results obtained from about 3000 samples shows that a high percentage of samples did not contain detectable pesticide residues or had residue levels below the maximum allowed by Italian law: 98% of the vegetables, 94.6% of the fruit, and 97.5% of the cereals (fumigants not considered here). On fruit, some residues exceeding the permissible levels for postharvest compounds, i.e., ethoxyquin, ethylenebisdithiocarbamate (EBDC), and benzimidazolmethylcarbamate (BMC), were found in apples and pears. Residue levels of some organochlorinated compounds slightly exceeding the legal limit were observed in some food samples of animal origin (mainly cow's milk). Comparing the present results with those of previous studies indicates that there has been a general decline in the residue levels of aldrin/dieldrin in milk and milk products.

Edible Grain↗
PubMed1986

Comparison of two techniques for quantitation of encysted cyathostome larvae in the horse.

Haustral portions of intestine of 6 horses were isolated by excising the taeniae coli from the cecum and the ventral colon. Uniform 5-cm X 5-cm sections were cut from the haustra and were illuminated from the serosal side with a strong light source (mural transillumination). Cyathostome larvae encysted in the mucosa and submucosa were observed at 15 X magnification and counted. Two separate counts of the larvae in 80 replicates of tissue by the mural transillumination technique (MTT) revealed no significant (P less than 0.05) difference between sample means. Larvae in tissue sections were counted in situ by MTT, and the mucosal scrapings of the tissue sections were digested in pepsin and HCl to determine larval yields for comparison with the MTT counts. Numbers of larvae recovered by pepsin and HCl digestion for 3 and 6 hours were significantly (P less than 0.01) lower than were numbers originally determined by MTT. Larvae recovered by tissue digestion for 3 or 6 hours were examined individually and given objective scores for morphologic damage. Distribution of scores was time-dependent; increased damage to larvae was associated with a longer time of digestion. Individual 4th-stage cyathostome larvae were dissected from cysts in the large intestinal wall and were incubated in water, 0.9% saline solution, 1.1% HCl, or pepsin (7,000 U of activity/ml). Significantly fewer (P less than 0.05) larvae were recovered from all solutions after 3 and 6 hours. The proportion of dissected larvae that were given high scores after exposure to pepsin was significantly (P less than 0.01) greater than were those held in HCl, saline solution, or water for both periods.

Animals↗