Video display for teaching fiberoptic intubations.
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Fiber Optic Technology↗
Biomedical subjects
K McDonald
Publications and source records attributed to K McDonald.
Electric field-mediated gene transfer: characterization of DNA transfer and patterns of integration in lymphoid cells.
Southern analysis of individual transfectants generated by electroporation demonstrated a strong preference for the integration of DNA in low copy number even when electroporation was performed in the presence of increasing DNA concentrations. Although transfer of multiple DNA copies was detected at higher DNA concentrations (16 pmoles/ml or greater), the average gene copy number even at 36 pmoles DNA per ml, was only 13. Multiple gene copies were integrated at either a few chromosomal sites, or at a single site within individual transfectants. Restriction endonuclease cleavage data were consistent with a random orientation of molecules within a concatemer, suggesting that the concatemer may have risen via end-to-end ligation of linear molecules, rather than by homologous recombination. Integration of exogenous DNA into the host chromosome occurred preferentially at the ends of the linear molecule. Although the linearization site was lost upon integration, endonuclease sites as close as 18 bp from the linearization site were retained. These data, as well as direct restriction mapping of the transferred genes, indicate that DNA transfer and integration occur without DNA rearrangement. Taken together, these results suggest that electroporation may offer some unique advantages for the transfer of eukaryotic genes.
Animals↗
Functional assessment of patients treated with permanent dual chamber pacing as a primary treatment for hypertrophic cardiomyopathy.
Patients with severe hypertrophic cardiomyopathy pose a difficult management problem. Between 1984 and 1986, 11 such patients have been treated by dual chamber pacing. (DDD). Subjectively all patients improved and objectively there was an increase in exercise tolerance during paced rhythm.
Adult↗
Spontaneous symbol acquisition and communicative use by pygmy chimpanzees (Pan paniscus).
Two pygmy chimpanzees (Pan paniscus) have spontaneously begun to use symbols to communicate with people. In contrast to common chimpanzees (Pan troglodytes) using the same communicative system, the pygmy chimpanzees did not need explicit training in order to form referential symbol-object associations. Instead, they acquired symbols by observing others use these symbols in daily communications with them. In addition, the pygmy chimpanzees have begun to comprehend spoken English words and can readily identify lexigrams upon hearing the spoken words. By contrast, common chimpanzees who received similar exposure to spoken English are unable to do so. The older pygmy chimpanzee has begun to form requests of the form agent-verb-recipient in which he is neither the agent nor the recipient. By contrast, similarly aged common chimpanzees limited their requests to simple verbs, in which the agent was always presumed to be the addressee and the chimpanzee itself was always the recipient, thus they had no need to indicate a specific agent or recipient. These results suggest that these pygmy chimpanzees exhibit symbolic and auditory perceptual skills that are distinctly different from those of common chimpanzees.
Animal Communication↗
Physiological and ultrastructural analysis of elongating mitotic spindles reactivated in vitro.
We have developed a simple procedure for isolating mitotic spindles from the diatom Stephanopyxis turris and have shown that they undergo anaphase spindle elongation in vitro upon addition of ATP. The isolated central spindle is a barrel-shaped structure with a prominent zone of microtubule overlap. After ATP addition greater than 75% of the spindle population undergoes distinct structural rearrangements: the spindles on average are longer and the two half-spindles are separated by a distinct gap traversed by only a small number of microtubules, the phase-dense material in the overlap zone is gone, and the peripheral microtubule arrays have depolymerized. At the ultrastructural level, we examined serial cross-sections of spindles after 1-, 5-, and 10-min incubations in reactivation medium. Microtubule depolymerization distal to the poles is confirmed by the increased number of incomplete, i.e., c-microtubule profiles specifically located in the region of overlap. After 10 min we see areas of reduced microtubule number which correspond to the gaps seen in the light microscope and an overall reduction in the number of half-spindle microtubules to about one-third the original number. The changes in spindle structure are highly specific for ATP, are dose-dependent, and do not occur with nonhydrolyzable nucleotide analogues. Spindle elongation and gap formation are blocked by 10 microM vanadate, equimolar mixtures of ATP and AMPPNP, and by sulfhydryl reagents. This process is not affected by nocodazole, erythro-9-[3-(2-hydroxynonyl)]adenine, cytochalasin D, and phalloidin. In the presence of taxol, the extent of spindle elongation is increased; however, distinct gaps still form between the two half-spindles. These results show that the response of isolated spindles to ATP is a complex process consisting of several discrete steps including initiation events, spindle elongation mechanochemistry, controlled central spindle microtubule plus-end depolymerization, and loss of peripheral microtubules. They also show that the microtubule overlap zone is an important site of ATP action and suggest that spindle elongation in vitro is best explained by a mechanism of microtubule-microtubule sliding. Spindle elongation in vitro cannot be accounted for by cytoplasmic forces pulling on the poles or by microtubule polymerization.
Actomyosin↗
Language learning in two species of apes.
A 4 year old pygmy chimpanzee (Pan paniscus) has spontaneously begun to use symbols for the purpose of communicating. Other apes have required training before they began to use symbols fluently. By contrast, this pygmy chimpanzee has begun to learn and appropriately employ graphic symbols simply as the result of exposure to human models. He has also spontaneously demonstrated an ability to comprehend many spoken English words and his multi-word utterances consistently provide more information than his single-word utterances.
Animal Communication↗
Effects of joint lavage on knee synovitis in rheumatoid arthritis.
Ten patients with rheumatoid arthritis and persistent knee synovitis had synovial fluid aspirated through a 14 gauge wide-bore needle followed by joint lavage and intra-articular triamcinolone. This resulted in the removal of variable quantities of intra-articular debris including rice bodies. When compared to a control group of patients, the addition of joint lavage to the standard procedure of aspiration and injection of corticosteroid resulted in more sustained resolution of synovitis after 12 weeks as judged by knee tenderness and circumference, recurrence of effusion, and synovial fluid leucocyte count. This study suggests that knee joint lavage may be a useful adjunct to therapy in rheumatoid arthritis patients having persistent knee synovitis.
Aged↗
Acute epiglottitis in adults.
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Acute Disease↗
Osmium ferricyanide fixation improves microfilament preservation and membrane visualization in a variety of animal cell types.
Using a fixation formula which includes adding potassium ferricyanide (K3Fe(CN)6) to the osmium step and an en bloc aqueous uranyl acetate step before dehydration we have looked at cells from mammals, birds, amphibia, algae, and higher plants and we have collaborated in fixing cells of teleost fish. In every cell type except the algae and higher plants the final EM image was improved by the OsFeCN-uranium method. The most common improvement was an increase in the membrane contrast but more significantly, some cells show improved preservation of microfilaments. We conclude that the OsFeCN adds contrast to all classes of membrane and does not destroy microfilaments to the extent that osmium alone does. Adding uranyl acetate to the cells may protect delicate filamentous structures from collapse during dehydration and embedding. We have preliminary evidence in PtK1 cells that addition of tannic acid after OsFeCN may function in a similar manner. This method is recommended for any animal cell type where improved visualization of membranes and filaments is required.
Animals↗
The frequent occurrence of neurological disease in patients with late-onset systemic lupus erythematosus.
Ten patients with systemic lupus erythematosus, whose first disease manifestation appeared after age 50 years, have been studied prospectively for up to five years. Neurological manifestations attributable to lupus occurred in nine patients and were multiple and varied. In all nine patients the neurological features appeared within one year of disease onset, and in four were present as an initial manifestation. Clinical recovery was generally satisfactory, and was complete in four. The apparent high incidence of neurological disease observed in late-onset lupus may help to elucidate causative mechanisms.
Adrenal Cortex Hormones↗
Oropharyngeal control of ingestion in rats: acquisition of sham-drinking patterns.
Rats with esophageal fistulas, offered a concentrated glucose solution, sham drank relatively small amounts on the first session. This was true whether or not such a solution was familiar. Intake rose to very high levels over ensuing sham-drinking sessions, a result showing that the initial small volumes were not attributable to fixed properties of the solution itself (e.g., aversiveness, viscosity, or input to "satiety" mechanisms). The gradual acquisition of copious sham drinking was not affected by previous "practice" at sham drinking other commodities; it was not simply an alteration in motor habits. Finally, the gradual acquisition of the sham-drinking pattern did not occur with more dilute solutions; in response to these, sham drinking was copious and continuous from the outset. The following conclusions are made: (a) Rats must learn to respond, by continuous drinking, to the absence of the postingestive inhibition normally produced by concentrated solutions. (It is a separate and open question whether the response to the presence of such inhibitory factors must also be learned.) (b) No such learning is required in the case of more dilute solutions. This is further evidence that controlling factors with differing properties operate at different levels even of the single commodity, glucose in solution.
Animals↗
A permeabilized cell model for studying cell division: a comparison of anaphase chromosome movement and cleavage furrow constriction in lysed PtK1 cells.
After lysis in a Brij 58-polyethylene glycol medium, PtK1 cells are permeable to small molecules, such as erythrosin B, and to proteins, such as rhodamine-labeled FAB, myosin subfragment-1, and tubulin. Holes are present in the plasma membrane, and the mitochondria are swollen and distorted, but other membrane-bounded organelles of the lysed cell model are not noticeably altered. After lysis, the mitotic apparatus is functional; chromosomes move poleward and the spindle elongates. Cells lysed while in cytokinesis will continue to divide for several minutes. Addition of crude tubulin extracts, MAP-free tubulin, or taxol to the lysis medium retards anaphase chromosome movements but does not affect cleavage. On the other hand, N-ethylmaleimide-modified myosin subfragment-1, phalloidin, and cytochalasin B inhibit cleavage but have no effect on anaphase chromosome movements under identical lysis conditions. These results suggest that actomyosin plays no functional role in anaphase chromosome movement in mammalian tissue culture cells and that microtubule depolymerization is a rate-limiting step for chromosome-to-pole movements.
Anaphase↗
Ultrasound of arterial graft surgery complications.
The value of gray scale ultrasound in evaluating primary diseases of the abdominal aorta and peripheral vessels has been well documented. However, only limited attention has been given to complications associated with arterial graft surgery. Twelve patients with a variety of complications are reported. These include 10 anastomotic pseudoaneurysms, one abscess, two "aneurysms" in degenerated graft material, and four serous fluid collections around intact Dacron grafts. The latter two complications are previously unreported.
Abscess↗
Toxicity of metabolic benzo(a)pyrenediones to cultured cells and the dependence upon molecular oxygen.
The three quinone metabolites of carcinogenic benzo(a)pyrene, the isomeric benzo(a)pyrenediones (6, 12; 1,6; 3,6), are toxic to cultured hamster cells at low concentrations. The reduction in cell number, observed after treatment with these metabolites, is the result of both direct cell killing and the inhibition of growth, since DNA synthesis is inhibited very early after treatment with benzo(a)pyrene 1,6-dione when little cell death has occurred. The rate of RNA synthesis was also inhibited by treatment of cells with benzo(a)pyrene 3,6-dione. These actions of the benzo(a)pyrenediones toward hamster cells can be eliminated or substantially reduced by the removal of oxygen from the growth medium and atmosphere in which the cells are incubated. In contrast, anaerobic conditions do not reduce the cytotoxicity observed with the alkylating agent ethyl methanesulfonate. These results support the hypothesis that benzo(a)pyrenediones, and other biologically active quinones, owe their activity to oxidation-reduction cycles involving quinone, hydroquinone, and molecular oxygen; the reactive reduced oxygen radicals and semiquinone radical formed during these cycles may be responsible for the observed cellular injury and inhibition of cellular processes.
Animals↗
Outreach and outrage: the student health coalition.
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Education, Medical↗
On the mechanism of anaphase spindle elongation in Diatoma vulgare.
Central spindles from five dividing cells (one metaphase, three anaphase, and one telophase) of Diatoma vulgare were reconstructed from serial sections. Each spindle is made up of two half-spindles that are composed almost entirely of polar microtubules. A small percentage of continuous microtubules and free microtubules were present in every stage except telophase. The half-spindles interdigitate at the midregion of the central spindle, forming a zone of overlap where the microtubules from one pole intermingle with those of the other. At metaphase the overlap zone is fairly extensive, but as elongation proceeds, the spindle poles move apart and the length of the overlap decreases because fewer microtubules are sufficiently long to reach from the pole to the zone of interdigitation. At telophase, only a few tubules are long enough to overlap at the midregion. Concurrent with the decrease in the length of the overlap zone is an increase in the staining density of the intermicrotubule matrix at the same region. These changes in morphology can most easily be explained by assuming zone mechanochemical interaction between microtubules in the overlap zone which results in a sliding apart of the two half-spindles.
Eukaryota↗
Poliomyelitis: epidemiology and prophylaxis. 4. Serological and virological surveys conducted after a mass vaccination campaign for the control of a threatening poliomyelitis epidemic.
In 1973, a type 1 poliomyelitis epidemic in Kenya was curtailed at an early stage by two mass distributions of trivalent oral vaccine. It was considered useful to know the immunity status of the child population that had resulted from the vaccine distributions and that had presumably contributed to its control. We also wished to know to what extent wild and vaccine virus strains were in circulation after the mass vaccination campaign. Anal swabs and blood were collected from a sample of the children in four areas where the efficiency of vaccine distribution had varied, and the results of virus isolation attempts and antibody tests are reported. Three poliovirus strains were isolated. It was surprising that, in general, the herd immunity after two vaccination rounds did not substantially differ from that found in Kenya on other occasions. Possible reasons for these results are discussed.
Age Factors↗
Poliomyelitis: epidemiology and prophylaxis. 5. Results of a two- and three-dose vaccination experiment.
In tropical countries, seroconversion rates following oral poliomyelitis vaccination are frequently unsatisfactory. In an area of the Machakos district in Kenya, 4000 children under 5 years of age have been registered and are visited fortnightly by trained field staff as part of a comprehensive, population-based, longitudinal surveillance project. It was considered possible that poliomyelitis vaccine, given orally to children twice or three times at home, would produce satisfactory conversion rates. After collection of blood from a random sample of the children, vaccine was given twice to all children under 5 years of age. Blood was then collected a second time from a different sample of children. After a third dose of vaccine, a third blood collection followed. The percentages of the children that received vaccine each round were calculated and the sera tested for antibodies. It appeared that the mean titre was more strongly related to age than to the number of doses of poliomyelitis vaccine received. Improvement of herd immunity after two vaccine distributions was significant for a few age groups and for two types of vaccine only. In none of the groups was a significant improvement obtained by the third vaccine distribution. The problems associated with vaccination by live poliomyelitis vaccine in tropical countries are discussed in relation to the results.
Age Factors↗