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Biomedical subjects

J Sands

Publications and source records attributed to J Sands.

At least 37 records · Page 2Linked to original sources
PubMed1982

Self-splicing RNA: autoexcision and autocyclization of the ribosomal RNA intervening sequence of Tetrahymena.

In the macronuclear rRNA genes of Tetrahymena thermophila, a 413 bp intervening sequence (IVS) interrupts the 26S rRNA-coding region. A restriction fragment of the rDNA containing the IVS and portions of the adjacent rRNA sequences (exons) was inserted downstream from the lac UV5 promoter in a recombinant plasmid. Transcription of this template by purified Escherichia coli RNA polymerase in vitro produced a shortened version of the pre-rRNA, which was then deproteinized. When incubated with monovalent and divalent cations and a guanosine factor, this RNA underwent splicing. The reactions that were characterized included the precise excision of the IVS, attachment of guanosine to the 5' end of the IVS, covalent cyclization of the IVS and ligation of the exons. We conclude that splicing activity is intrinsic to the structure of the RNA, and that enzymes, small nuclear RNAs and folding of the pre-rRNA into an RNP are unnecessary for these reactions. We propose that the IVS portion of the RNA has several enzyme-like properties that enable it to break and reform phosphodiester bonds. The finding of autocatalytic rearrangements of RNA molecules has implications for the mechanism and the evolution of other reactions that involve RNA.

Animals↗
PubMed1982

Protection against bovine leukosis virus infection in sheep with the BL 20 bovine lymphoblastoid cell line.

The bovine lymphoblastoid BL 20 cell line derived from a case of sporadic bovine leukosis when inoculated into sheep did not induce an antibody response directed against bovine leukosis virus (BLV) structural proteins. Sheep were inoculated twice with the BL 20 cell line and then challenged with BLV infected lymphocytes. Three out of four sheep challenged four weeks after BL 20 inoculation did not develop BLV antibodies. Of the 12 sheep challenged later, three sheep did not develop BLV antibodies. BLV was isolated from all the seropositive animals and from none of the seronegative animals.

Animals↗
PubMed1980

Mechanism of virucidal activity of retinoids: protein removal from bacteriophage phi 6 envelope.

The mechanism of the potent virucidal activity of retinol (vitamin A) and retinal (vitamin A aldehyde) was investigated for the interaction of these compounds with a model system enveloped virus, bacteriophage phi 6. The retinoids bind to and inactivate phi 6 without causing large-scale disruption of the virion. Inactivated virions have completely lost the ability to adsorb to host bacteria due to the loss of a viral envelope protein necessary for adsorption.

Antiviral Agents↗
PubMed1979

Cell number and cell size: organ growth and development and the control of catch-up growth in rats.

One of the most important hypotheses for the control of catch-up after nutritional growth restriction relates developmental vulnerability to an early phase of cell multiplication, rather than to a later phase of growth of cell size. A re-examination of growing tissues, however, does not show the expected sequence of growth events, and the former hypothesis is therefore not supported.

Aging↗
PubMed1979

Extreme sensitivity of enveloped viruses, including herpes simplex, to long-chain unsaturated monoglycerides and alcohols.

Unsaturated monoglycerides and alcohols of chain lengths of 16 or 18 carbons were found to be extremely potent inactivators of two enveloped viruses, herpes simplex virus type 2 and bacteriophage phi6. The lipid-containing bacteriophage PM2 was also inactivated by some of these amphiphilic molecules. Treatment of herpes simplex virus type 2 with these compounds at concentrations as low as 0.2 muM reduced virus survival to 50% in 30 min, making these agents the most potent inactivators of herpes simplex viruses discovered that are not cytotoxic to mammalian cells. Detailed characterizations of the effects of unsaturated monoglycerides and alcohols on bacteriophages phi6 and PM2 showed that the inactivated phi6 virion remained nearly intact but that PM2 was almost completely disrupted by the inactivating treatment. Some of the compounds inactivate the viruses even at low temperature (0 degrees C). Excess amounts of diglycerides and phospholipids interfere with the inactivating abilities of some of the unsaturated monoglycerides and alcohols against phi6 and PM2. Our findings suggest that the unsaturated monoglycerides and some of the unsaturated alcohols should be further studied as potential antiviral agents, particularly for application to herpesvirus-infected areas of the skin and accessible epithelium.

Bacteriophages↗
PubMed1978

Training in allergy.

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Allergy and Immunology↗
PubMed1978

Head circumference, biparietal diameter and brain growth in fetal and postnatal life.

The curves for biparietal diameter, head circumference and brain weight with increasing age have different shapes, and these differences have been explained. Interconversion procedures are suggested. One important consequence of changing growth velocities relates to assessing prognosis for catch-up following adversity. On the assumption that catch-up of brain growth must occur within the period of the brain weight growth spurt, the interpretation of head circumference charts is discussed.

Brain↗
PubMed1977

Regional and segmental characteristics of the human adult spinal cord.

Ten human adult spinal cords were assessed for weight, length, thickness, cholesterol, water and DNA-P content on both a regional and a mean segmental regional basis. The mean segmental DNA-P content, unlike the other parameters, was exceptional in being constant in the cervical, thoracic and lumbar regions. It is concluded that the cellularity of the cord between C1 and L5 is determined segmentally, but is reduced in the segments of the sacrococcygeal cord because of embryonic atrophy.

Adult↗
PubMed1976

Inactivation of the enveloped bacteriophage phi6 by butylated hydroxytoluene and butylated hydroxyanisole.

Butylated hydroxytoluene (BHT) is a potent inactivator of the enveloped bacterial virus ø6 at concentrations as low as 3 x 10(-5) M. The viral envelope is not removed by BHT treatment, in contrast to the effects of exposure to the detergent Triton X-100. BHT-treated viruses are morphologically indistinguishable from controls but are defective in their ability to attach to the host cell. Temperature at the time of exposure was found to be a crucial factor in the effectiveness of BHT against ø6. A precipitous drop in the degree of inactivation by 3 x 10(-5) M BHT occurred when the temperature was lowered from 20 to 15 C. Calcium ions were found to potentiate the effect of BHT, particularly at lower temperatures where BHT alone was relatively ineffective. Barium and strontium, but not magnesium, were also effective in enhancing the activity of BHT. A structurally related molecule, butylated hydroxyanisole (BHA), was also found to inactivate ø6 virus, but higher concentrations were required than with BHT. Both BHT and BHA are commonly used as food additives, have apparent low toxicity to humans and other animals, and are potentially useful as antiviral agents.

Anisoles↗
PubMed1975

Effect of lipid alkyl chain perturbations on the assembly of bacteriophage PM2.

The lipid-containing bacteriophage PM2 can produce infectious virus in cultures infected at temperatures up to 31.5 degrees C, but not at 34 degrees C. Its host, Pseudomonas BAL-31, grows at 34 degrees C and cultures infected at that temperature undergo lysis. Sucrose-gradient analysis shows that 34 degrees C lysates contain no PM2-like particles. Temperature-shift experiments establish that the thermally sensitive process is late in infection when virus assembly is taking place. Adamantanone, a small hydrophobic molecule that perturbs membrane hydrocarbon zones, prevents the production of infective virus. Concentrations which prevent virus production have no effect on host-cell growth or stability of mature virions. Adamantanone exerts its effects late in the infectious cycle, and lysates amde in its presence contain no PM2-like particles. These experiments, carried out at 25 degrees C, indicate that adamantanone prevents the assembly of stable PM2 virus. Spin-label studies suggest that the lipid alkyl chains of the host-cell membrane are in an "ordered" state at temperatures below about 33 degrees C and undergo a transition to a "disordered" state above that temperature. Furthermore, the addition of adamantanone perturbs the hydrocarbon zones, producing a greater degree of disorder even below 25 degrees C. Our findings suggest that the cell membrane can function and grow with the lipid alkyl chains in either the "ordered" or "disordered" state, but that the "ordered" state must be maintanined for PM2 assembly to occur.

Anti-Bacterial Agents↗
PubMed1975

Physical and biochemical characteristics of the human dysraphic spinal cord.

The spinal cords were removed from 29 infants between 17 and 46 weeks gestation, all with various forms of spinal dysraphia. The spinal cords were assessed for weight, length, thickness, size and number of cells, and myelination, and then were compared with 86 control spinal cords. The strongest characteristic of the dysraphic cords was a reduced degree of myelination. Cell size and number generally were appropriate for the weight of the cords. There was a tendency for cord weight, length and thickness to be reduced, though in part this was a reflection of poor over-all bodily growth. In a small group of infants these measurements were increased in comparison with the controls.

Body Water↗