Non-surgical recovery of bovine eggs.

An improved, non-surgical technique for recovering bovine eggs is described using modified Foley catheters. Egg recovery rates per attempt were, $\text{36}\text{51}$ (71%), for normal, unsuperovulated donors and $\text{4}\text{38}$ (11%), for unsuperovulated donors with known fertility problems. For superovulated donors, eggs were collected in $\text{24}\text{26}$ attempts (92%) averaging 6.9 per recovery.     

Anaerobic recovery in man.

The lactic acid (L.A.) concentration in blood after a 20 sec supramaximal exercise (2.5 times VO2max) has been measured in 4 subjects in the following experimental conditions: a) during the resting period following the supramaximal exercise (rest recovery) and b) during a 3 min exercise at VO2max immediately following the supramaximal effort (exercise recovery). The L.A. concentration in blood has been found to be consistently higher (on the average by 16.9 mg%) in case (b). Since in such condition it may be reasonably assumed that the oxygen taken up by the subject is completely utilized for the exercise, the increase of blood lactate is considered evidence for the occurrence of anaerobic recovery, i.e. of a partial re-synthesis of the high energy phosphate stores of the muscle (GP = ATP + PC) depleted during the supramaximal effort, at the expense of anaerobic glycolysis. From the increase in blood L.A. concentration during the anaerobic recovery period, the amount of L.A. produced has been estimated together with the amount of GP resynthesized. The latter corresponds to 4 to 7 mMoles/kg of muscle, i.e. to about 25% of the average GP concentration in resting human muscle. The finalistic implication of this mechanism is the prompt restoration of the potential maximal power of the muscle even in the absence of O2.     

Coevolution of recovery ability and virulence.

Most models for coevolution of hosts and parasites are based on the assumption that resistance of hosts to parasites is an all-or-nothing effect. In many cases, for example where parasites require an appropriate receptor on host cells, this is a reasonable assumption. However, in many other cases, for example where hosts mount an immune response, this picture may be too simple. An immune system is expensive to maintain, which poses a question as to how much of its resources a host should allocate to resist parasites: if the risk of infection is low, natural selection may favour hosts with less effective immune systems. As optimal allocation to defence will depend on the force of infection, and the force of infection, in turn, depends on the level of defence in the rest of the host population, a game-theoretic approach is necessary. Here I analyse a simple model for the evolution of the ability to recover from infection. If parasites are not allowed to coevolve, the outcome is a single evolutionarily stable strategy (ESS). If the parasites coevolve, multiple evolutionary outcomes are possible, one in which the parasites are relatively avirulent and common and the hosts invest little in recovery ability, and another (the escalated arms race) where parasites are rare but virulent and the hosts invest heavily in defence.     

Profile of recovery after general anaesthesia.

The duration of impairment of mental functioning after anaesthesia was studied in 55 patients undergoing hernia repair who were divided into three groups in which the method of induction of anaesthesia (intravenous or inhalational) and ventilation (spontaneous or controlled) was varied. Performance in a five minute serial reaction time test and subjective estimates of coordination were assessed four times a day for two complete postoperative days and were compared with those in a control group of orthopaedic patients in hospital. After considerable impairment initially, reaction times in all groups gradually returned towards control values, but in patients breathing spontaneously during anaesthesia impairment recurred during the second postoperative day. These results suggest that such patients should be advised not to undertake hazardous tasks such as driving a car for at least 48 hours after a general anaesthetic. Discrepancies between subjective and objective assessments of impairment also suggest that patients should not rely on their own assessments of fitness to drive.     

Integrated product formation and recovery.

As continues to be demonstrated, the in situ recovery of selected products froma bioreactor can have a significant positive impact on production. The strategies that are focused on here are: aqueous two-phase biocatalysis; non-aqueous biocatalysis; and membrane-enhanced biocatalysis. Additional fundamental understanding of molecular partitioning and biocatalytic activity in these environments will facilitate the rational selection of the components involved in these processing strategies.     

DNA recovery from soils of diverse composition.

A simple, rapid method for bacterial lysis and direct extraction of DNA from soils with minimal shearing was developed to address the risk of chimera formation from small template DNA during subsequent PCR. The method was based on lysis with a high-salt extraction buffer (1.5 M NaCl) and extended heating (2 to 3 h) of the soil suspension in the presence of sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide, and proteinase K. The extraction method required 6 h and was tested on eight soils differing in organic carbon, clay content, and pH, including ones from which DNA extraction is difficult. The DNA fragment size in crude extracts from all soils was > 23 kb. Preliminary trials indicated that DNA recovery from two soils seeded with gram-negative bacteria was 92 to 99%. When the method was tested on all eight unseeded soils, microscopic examination of indigenous bacteria in soil pellets before and after extraction showed variable cell lysis efficiency (26 to 92%). Crude DNA yields from the eight soils ranged from 2.5 to 26.9 micrograms of DNA g-1, and these were positively correlated with the organic carbon content in the soil (r = 0.73). DNA yields from gram-positive bacteria from pure cultures were two to six times higher when the high-salt-SDS-heat method was combined with mortar-and-pestle grinding and freeze-thawing, and most DNA recovered was of high molecular weight. Four methods for purifying crude DNA were also evaluated for percent recovery, fragment size, speed, enzyme restriction, PCR amplification, and DNA-DNA hybridization. In general, all methods produced DNA pure enough for PCR amplification. Since soil type and microbial community characteristics will influence DNA recovery, this study provides guidance for choosing appropriate extraction and purification methods on the basis of experimental goals.     

Kinetics of haemopoietic recovery in endotoxin-treated mice.

Kinetics of mouse spleen colony forming units were studied after intra-peritoneal injection of 1 mug/blody weight bacterial endotoxin S. typhosa. When these mice were used as unirradiated and sublethally irradiated donors, it was possible to study the effect of the endotoxin injection upon the cells.Use of the treated mice as irradiated recipients of normal cells gave information about the host effect. In treated unirradiated mice, the total nucleated cell and the CFU counts were disturbed, and 2 days later a large fraction of the CFU were found in the DNA synthesis (S) phase. This meant that injection of endotoxin generated factors affecting the kinetics of the CFU and triggering the resting CFU into the proliferative cycle. If then the mice were given supralethal irradiation and used as recipients of normal bone marrow cells, more CFU seeded to the spleen as compared to normal recipients; but the dip and the growth rate of the CFU were not changed. Hence the endotoxin-generated factors had been eliminated in 2 days. A total body sublethal irradiation by 400 rad X-ray 2 days after endotoxin injection reduced the post-irradiation dip in the recovery curve of the CFU, indicating that though the factors affecting the cell kinetics had been eliminated, the cycling CFU behaved like a growing population. During the first week, the growth rate of the CFU remained the same as in control irradiated mice. The growth rate of the spleen CFU of the endotoxin-treated mice slowed down during the second week, and their self-replicating ability was low. Fluctuations in the DNA synthesizing fraction of the spleen CFU suggested a variability in the ratio of the length of the S phase and the cell generation time.     

Theoretical analysis of fluorescence photobleaching recovery experiments.

We derive an exact closed formula for the fluorescence recovery curve measured in fluorescence photobleaching recovery experiments employing uniform circular laser beams. In contrast to the expression used currently, this result is very simple and free of mathematical drawbacks, thus facilitating the quantitative analysis of experimental data.     

Importance of interferons in recovery from mousepox.

Gamma interferon is shown to be critical in recovery of C57BL/6 mice from mousepox. Anti-gamma interferon treatment of mice infected in the footpad with ectromelia virus resulted in enhanced spread to and efficient virus replication in the spleen, lungs, ovaries, and, especially, liver. All treated, infected mice died within a mean of 7 days, 2.5 days earlier than mice with severe combined immunodeficiency that were given a comparable infection. On the other hand, alpha interferon appeared not to have a major role in controlling virus replication in tissues examined, and beta interferon was important for virus clearance in the liver and ovaries but not the spleen. Either anti-alpha, beta interferon or anti-beta interferon antibody therapy resulted in only 25% mortality. Infected control mice survived but showed persistence of ectromelia virus at the site of infection (the footpad) and transient presence of the virus in the spleen, liver, lungs, and ovaries and in the fibroreticular but not lymphoid cells of the draining popliteal lymph node. Depletion of gamma interferon but not alpha and/or beta interferon resulted in a significant reduction in the numbers of splenic T (especially gamma delta-TCR+), B, and Mac-1+ cells, although the proportion of Mac-1+ cells in the spleen increased compared with control values. Depletion of alpha, beta, or gamma interferons did not severely affect the generation of virus-specific cytotoxic T-lymphocyte responses or natural killer cell cytolytic activity. This study, in which a natural virus disease model was used, underscores the crucial importance of gamma interferon in virus clearance at all stages of infection and in all tissues tested except the primary site of infection, where virus clearance appears to be delayed.     

Efficient recovery and regeneration of integrated retroviruses.

We report a rapid and efficient PCR-based rescue procedure for integrated recombinant retroviruses. Full-length proviral DNA is amplified by long-range PCR using a pair of primers derived from the long terminal repeats (LTR), and virus is regenerated by transfecting retrovirus-packaging cells with the PCR-derived provirus. The viral yield from the PCR product is similar to that from the retroviral plasmid vector, and the representation of different inserts is accurately maintained in the recovered retroviral population. This procedure is suitable for expression cloning from retroviral libraries and should be applicable to the analysis of natural retrovirus populations.