Flap failure after microvascular free-tissue transfer: the fate of a second attempt

In most cases, the loss of a free-tissue transfer is a disaster for both the patient and the surgeon. Seven patients received a second microvascular free-tissue transfer after loss of the first. The indications for free-tissue transfer included chronic osteomyelitis of the lower leg (four patients), acute traumatic defect of the leg (one patient), acute traumatic defect of the arm (one patient), and esophageal defect after surgical excision (one patient). In three patients, the interval between the first and second procedures was less than 2 weeks. The remaining four patients had their second free-tissue transfer performed 5 weeks to 21 months after the first. Six of the seven free flaps were successful. Two patients with venous obstruction occurring after the second free-tissue transfer were salvaged by reexploration. Partial loss of the flap was noted in one of these patients. It is concluded from this select group of patients that failure of a free-tissue transfer does not contraindicate a second microtissue transfer does not contraindicate a second microvascular free-tissue transfer.     

Sensible and latent heat loss from the body surface of Holstein cows in a tropical environment

The general principles of the mechanisms of heat transfer are well known, but knowledge of the transition between evaporative and non-evaporative heat loss by Holstein cows in field conditions must be improved, especially for low-latitude environments. With this aim 15 Holstein cows managed in open pasture were observed in a tropical region. The latent heat loss from the body surface of the animals was measured by means of a ventilated capsule, while convective heat transfer was estimated by the theory of convection from a horizontal cylinder and by the long-wave radiation exchange based on the Stefan–Boltzmann law. When the air temperature was between 10 and 36°C the sensible heat transfer varied from 160 to –30 W m^–2, while the latent heat loss by cutaneous evaporation increased from 30 to 350 W m^–2. Heat loss by cutaneous evaporation accounted for 20–30% of the total heat loss when air temperatures ranged from 10 to 20°C. At air temperatures >30°C cutaneous evaporation becomes the main avenue of heat loss, accounting for approximately 85% of the total heat loss, while the rest is lost by respiratory evaporation.Part of first authors doctoral thesis     

Mapping of the flo5 gene ofSaccharomyces cerevisiae by transfer of a chromosome during cytoduction

Summary Cytoduction has been used to confer flocculation to a nonflocculent straint. The transfer of the chromosome I of a FLO5 strain in a recipient strain was enough to induce its flocculation. We observed by chromosome loss experiments that the loss of flocculation was correlated with the loss of chromosome I. It can be concluded from these observations that FLO5 is localized on chromosome I.     

Disappearance and effects of exogenous lipid transfer activity in rats

These studies were performed to determine the role of plasma lipid transfer activity in the regulation of plasma total and lipoprotein cholesterol in vivo. Partially purified human lipid transfer activity was injected into rats at a level similar to that of normal rabbit plasma, d greater than 1.21. The disappearance of exogenous lipid transfer activity from rat plasma was biphasic, with a 70% loss within 6 h. The remaining 30% was lost with a half-time of about 14 h. In the rat, short-term exposure (6 h) to high levels of lipid transfer activity resulted in a net transfer of cholesteryl esters from high density to d less than 1.019 lipoproteins, without affecting plasma total cholesterol. However, the lipid transfer activity-induced changes in lipoprotein cholesterol were not evident after 24 h, despite the fact that the lipid transfer activity of rat plasma d greater than 1.21 was similar to that of human plasma d greater than 1.21 during the preceding 18 h.     

Differentiation of chick embryo cerebral hemispheres: a critical evaluation of a bulk preparation of neuroblasts and spongioblasts

Abstract— A critical evaluation of a previously described method of bulk preparation of neuroblasts and spongioblasts from chick embryo cerebral hemispheres furnished the following results.

• 1 A major loss of total RNA occurs during the preparation of the cell fractions.
• 2 The loss occurred mainly during the dissociation of the tissue and the following centrifugations.
• 3 The missing RNA's were found in the supernatants after cell centrifugation at low speed.
• 4 There was a selective loss of transfer RNA amounting to 70–80 per cent relative to ribosomal RNA.
• 5 The relative proportions of the 29, 18 and 5s ribosomal RNA's were constant, but there was a decrease in their proportion relative to heavy-molecular weight, rapidly-labelled nuclear RNA.
• 6 The ribosomal RNA's in the low-speed supernatant could be resedimented at 35,000 g whereas most transfer RNA could not.

The results are consistent with a loss of fragments of cytoplasm containing ribosomes and with additional extraction of transfer RNA during the preparation.     

Measurement of distance between the active serine of the thioesterase domain and the pantetheine thiol of fatty acid synthase by fluorescence resonance energy transfer

Fatty acid synthase from the uropygial gland was inactivated by treatment with pyrenebutyl methanephosphonofluoridate by specific modification of the "active serine" at the thioesterase domain. Treatment of fatty acid synthase with 3-(4-maleimidylphenyl)-7-diethylamino-4-methylcoumarin resulted in the loss of the condensation activity and overall synthase activity. Acetyl-CoA and malenyl-CoA protected the enzyme from inactivation by this reagent suggesting that the pantetheine thiol was modified. In support of this conclusion was the finding that modification of the primer-binding thiol with iodoacetamide prior to the modification with the coumarin derivative resulted in no change in the binding of the coumarin to the enzyme. Furthermore, the presumptive active site peptide isolated after proteolysis released its attached coumarin upon treatment with alkali under beta-elimination reaction conditions. Graphical analysis of the binding data suggested that binding of one coumarin derivative/subunit of the synthase would result in complete loss of the synthase activity. When the synthase was modified with the coumarin and pyrene derivatives, fluorescence resonance energy transfer occurred from the pyrene at the thioesterase site to the coumarin attached to the pantetheine thiol. Dissociation of the enzyme to monomers did not decrease the efficiency of transfer, but limited trypsin treatment, which released the thioesterase domain, abolished the fluorescence resonance energy transfer. These results suggested that the energy transfer occurred between intrasubunit sites. The distance between the pyrene at the thioesterase active site and the coumarin attached to pantetheine thiol on the same subunit of fatty acid synthase was estimated from the efficiency of energy transfer to be 37 A.     

Effect of Heparin on Prevention of Flap Loss in Microsurgical Free Flap Transfer: A Meta-Analysis

The effectiveness of heparin for thromboprophylaxis during microvascular free flap transfer is uncertain. The purpose of this meta-analysis was to determine the effect of heparin on the prevention of flap loss in microsurgical free flap transfer.A search of PubMed, Cochrane databases, and Google Scholar using combinations of the search terms heparin, free flap, flap loss, free tissue transfer was conducted on March 15, 2013. Inclusion criteria were: 1) Prospective randomized trials. 2) Retrospective, non-randomized studies. 3) Patients received free tissue transfer. Flap loss rate was used to evaluate treatment efficacy. Odds ratios (ORs) with 95% confidence intervals (CI) were calculated and compared between therapies. Four studies meet the criteria for analysis and were included. Two studiescompared aspirin and heparin, and the ORs of the 2 studies were 1.688 and 2.087. The combined OR of 2.003 (95% CI 0.976–4.109, p = 0.058) did not indicate any significant difference between heparin and aspirin therapies. Two studiescompared high and low doses of dalteparin/heparin therapies, and the ORs of the 2 studies were 4.691 and 11.00. The combined OR of 7.810 (95% CI 1.859–32.808, p = 0.005) revealed a significant difference indicating that high dose dalteparin or heparin therapy is associated with a greater flap loss rate than low dose therapy. Heparin and aspirin prophylaxis are associated with similar flap loss rates after free flap transfer, and high dose dalteparin or heparin therapy is associated with a greater flap loss rate than low dose therapy.     

Effects of injecting exogenous lipid transfer protein into rats

Rats were injected intravenously with preparations of partially purified lipid transfer protein isolated from human plasma. Cholesteryl ester transfer activity disappeared from the plasma of recipient rats with a t1/2 of about 10 h and after 24 h had fallen to a level comparable to that in human plasma. By contrast there was no measurable cholesteryl ester transfer activity in the plasma of control rats. Plasma collected from rats 24 h after the injection was subjected to ultracentrifugation at 1.225 g/ml; lipoproteins in the 1.225 g/ml supernatant were subsequently separated by both gel filtration chromatography and gradient gel electrophoresis. The major change in the treated animals was a total loss of the large, cholesteryl ester-rich, apolipoprotein E-rich high-density lipoproteins, HDL1, which are prominent in the plasma of control rats. This loss of HDL1 unmasked an obvious peak of low-density lipoproteins that had been obscured in the control rats. Other changes in the treated rats included an increase in the relative cholesteryl ester content of very-low-density lipoproteins and the emergence of a peak of triacylglycerol in the high-density lipoproteins.     

Equilibrium and kinetics studies of transnitrosation between S-nitrosothiols and thiols

Using UV-vis spectrometrical measurements, equilibrium constants for NO transfer between S-nitroso-N-acetyl-penicillamine (SNAP) and different thiols as well as kinetic data for NO transfer from S-nitroso bovine serum albumin (BSANO) to thiols have been obtained. NO transfer from SNAP to other primary/secondary thiols are thermodynamically favorable, whereas other S-nitrosothiols exhibit similar NO transfer potential. The obtained Gibbs free energy, enthalpy and entropy data indicated that NO transfer reactions from SNAP to four thiols are exothermic with entropy loss. The kinetic behavior of BSANO/RSH transfer can be related to both the acidity of sulfhydryl group and the electronic structure in thiol.     

Plasmid required for virulence of Agrobacterium tumefaciens.

The irreversible loss of crown gall-inducing ability of Agrobacterium tumefaciens strain C-58 during growth at 37 C is shown to be due to loss of a large plasmid (1.2 X 10-8 daltons). The gene responsible for this high rate of plasmid loss at elevated temperatures seems to be located on the plasmid. In addition, another spontaneous avirulent variant, A. tumefaciens strain IIBNV6 is shown to lack the virulence plasmid which its virulent sibling strain, IIBV7, possesses. Deoxyribonucleic acid reassociation measurements prove that the plasmid is eliminated, not integrated into the chromosome, in both of the avirulent derivatives. Transfer of virulence from donor strain C-58 to avirulent recipient strain A136 results from the transfer of a plasmid, which appears identical to the donor plasmid by deoxyribonucleic acid reassociation measurements. The transfer of virulence in another cross, K27 X A136, was also shown to result from the transfer of a large plasmid. These findings establish unequivocally that the large plasmid determines virulence. Two additional genetic determinants have been located on the virulence plasmid of A. tumefaciens strain C-58: the ability to utilize nopaline and sensitivity to a bacteriocin produced by strain 84. The latter trait can be exploited for selection of avirulent plasmid-free derivatives of strain C-58. The trait of nopaline utilization appears to be on the virulence plasmid also in strains IIBV7 and K27.     

Solid Loss of Carrots During Simulated Gastric Digestion

The knowledge of solid loss kinetics of foods during digestion is crucial for understanding the factors that constrain the release of nutrients from the food matrix and their fate of digestion. The objective of this study was to investigate the solid loss of carrots during simulated gastric digestion as affected by pH, temperature, viscosity of gastric fluids, mechanical force present in stomach, and cooking. Cylindrical carrot samples were tested by static soaking method and using a model stomach system. The weight retention, moisture, and loss of dry mass were determined. The results indicated that acid hydrolysis is critical for an efficient mass transfer and carrot digestion. Internal resistance rather than external resistance is dominant in the transfer of soluble solids from carrot to gastric fluid. Increase in viscosity of gastric fluid by adding 0.5% gum (w/w) significantly increased the external resistance and decreased mass transfer rate of carrots in static soaking. When mechanical force was not present, 61% of the solids in the raw carrot samples were released into gastric fluid after 4 h of static soaking in simulated gastric juice. Mechanical force significantly increased solid loss by causing surface erosion. Boiling increased the disintegration of carrot during digestion that may favor the loss of solids meanwhile reducing the amount of solids available for loss in gastric juice. Weibull function was successfully used to describe the solid loss of carrot during simulated digestion. The effective diffusion coefficients of solids were calculated using the Fick’s second law of diffusion for an infinite cylinder, which are between 0.75 × 10⁻¹¹ and 8.72 × 10⁻¹¹ m²/s, depending on the pH of the gastric fluid.     

Factors potentially affecting fertility of lactating dairy cow recipients

Objectives of this study were to evaluate factors that could affect pregnancy rate after embryo transfer (ET) in lactating dairy cow recipients. The trial was conducted at a dairy farm located in Descalvado, SP, Brazil from October 2003 to September 2004. From 1037 cows with CL that were treated with an injection of PGF2alpha, 43.3% were detected in heat; 263 were previously assigned at day of PGF2alpha injection for AI and 186 for ET. Ovulation rate was 85.7% (385/449). Pregnancy rate for cows with CL for AI and embryo transfer recipients were 36.5% (84/230) and 58.7% (91/155) at day 25 and 33.0% (76/230) and 45.8% (71/155) at day 46, respectively. Embryonic loss were 9.5% (8/84) for the AI group and 21.9% (20/91) for the ET group. Average milk production was 31.4 L/day/cow. Average daily milk production from 7 days before PGF2alpha injection to 7 days after ET tended (P < 0.10) to influence pregnancy rate on days 25 and 46. Average daily milk production from the day of embryo transfer to 7 days after influenced embryonic loss (P < 0.05). Cows with higher milk production had lower probability of pregnancy and higher probability of embryonic loss. Cows with higher days in milk had higher probability of pregnancy. Cows with higher rectal body temperature had lower probability of pregnancy and higher probability of embryonic loss. The influence of high milk yield and body temperature on fertility in lactating dairy cow recipients suggests that these effects can occur also after embryo reaches the blastocyst stage.     

Heat transfer in elephants: thermal partitioning based on skin temperature profiles

The elephant with its low surface-to-volume ratio presents an interesting problem concerning heat dissipation. To understand how such large mammals remain in thermal balance, we determined the major avenues of heat loss for an adult African elephant and an immature Indian elephant. Because conventional physiological measurements are difficult for these animals, the present study used a non-invasive technique, infrared thermography, to measure skin temperatures of each elephant. Detailed surface temperature profiles and surface area measurements of each elephant were used in standard equations for convective, conductive and radiant heat transfer. Results demonstrated that heat transfer by free convection and radiation accounted for 86% of the total heat loss for the elephants at T _a= 12·6 °C. Heat transfer across the ears, an important thermal window at high ambient temperatures, represented less than 8% of the total heat loss. Surface area of the animals, and metabolic heat production calculated from total heat loss of the African elephant, scaled predictably with body mass. In contrast, the thermal conductance of the elephants (71·6 W /°C, African; 84·5 W /°C, Indian) was three to five times higher than predicted from an allometric relationship for smaller mammals. The high thermal conductance of elephants is attributed to the absence of fur and appears to counteract reduced heat transfer associated with a low surface-to-volume ratio.     

Estimation of Plasmid Loss Rates in Bacterial Populations with a Reference to the Reproducibility of Stability Experiments

Two methods for estimation of plasmid loss rates were tested on data obtained from traditional (serial transfer) stability experiments. The first method was based on the assumption that the plasmid does not inhibit the growth of its host, whereas the second method takes differences in the interdivision time of plasmid-free and plasmid-carrying cells into account. In the cases where the loss rate is high and the plasmid does not exert strong growth inhibition, the estimates appear very reliable. When the plasmid loss rate is small and the plasmid exerts inhibition of growth to its host, the experimental design becomes unreliable.     

Individual fish tank arrays in studies of Lepeophtheirus salmonis and lice loss variability

In studies of the salmon louse Lepeophtheirus salmonis (Kr?yer, 1837), experimental design is complicated by a highly variable and unpredictable lice loss among common experimental tanks and a substantial rate of host transfer within tanks. When fish hosting L. salmonis are maintained in individual tanks, unspecific effects such as host transfer, louse predation by cohabitant hosts and agonistic host interactions are excluded. This study suggests that it is possible to maintain Atlantic salmon Salmo salar infected with L. salmonis in an array of small, single fish tanks and, by doing so, provide an experimental system in which the loss of motile pre-adult and adult stages of L. salmonis is predictable. Here, lice can be collected shortly after detachment for detailed studies or to provide mortality curves of lice from individual fish. This represents an experimental approach improving precision in studies of L. salmonis, such as drug and vaccine efficacy assays, RNA interference (RNAi) studies and host-parasite interactions. The natural loss of pre-adult/adult L. salmonis from the system was higher for males than females. The loss of females appeared to be a process somewhat selective against large individuals. Inherent qualities of the host appeared to be of little significance in explaining the variability in loss of preadult/adult lice.     

Laparoscopic transfer of ovine and cervine embryos using the transpic technique

A transpic technique was developed to transfer embryos to 352 sheep and 4 deer recipients using a laparoscope, a modified pair of Allis forceps and a modified Cassou aspic normally used for laparoscopic uterine insemination. The overall proportion of uncomplicated transfers in Experiment 1 in 216 recipient ewes was 90.7% (range between groups 80 to 100%), 3.7% of the transfers were presumed to be loss of embryos during expulsion from the transpic, and 5.6% were apparent transfers into the uterine wall. In Experiment 2,83% of transfers into 136 ewe recipients were uncomplicated, 5% were presumed to be loss of embryos during expulsion, 1% was apparent transfer into the uterine wall, and 11% involved 2 attempts at transfer. Only 34% of 116 recipients receiving low-quality frozen-thawed embryos were pregnant and 24% of the 226 embryos survived to term. In contrast, high pregnancy rates (>80%) and embryo survival rates (>70%) were achieved following uncomplicated and twice attempted transfers of fresh embryos. Pregnancy rates and embryo survival rates were low (<2%) following the presumed loss of embryos during expulsion and apparent transfers into the uterine wall. All 4 deer transfers were uncomplicated and 2 2 good-quality embryos survived to term compared with 0 2 low-medium quality embryos. The transpic technique is a moderately invasive technique which permits fast (15 to 20/h) and reliable transfer of embryos in small ruminants. With appropriate care, nearly all of the embryos can be correctly placed in the uterus, and high pregnancy rates and embryo survival rates can be achieved using this technique.     

Roles of NapF, NapG and NapH, subunits of the Escherichia coli periplasmic nitrate reductase, in ubiquinol oxidation

The nap operon of Escherichia coli K-12, encoding a periplasmic nitrate reductase (Nap), encodes seven proteins. The catalytic complex in the periplasm, NapA-NapB, is assumed to receive electrons from the quinol pool via the membrane-bound cytochrome NapC. Like NapA, B and C, a fourth polypeptide, NapD, is also essential for Nap activity. However, none of the remaining three polypeptides, NapF, G and H, which are predicted to encode non-haem, iron-sulphur proteins, are essential for Nap activity, and their function is currently unknown. The relative rates of growth and electron transfer from physiological substrates to Nap have been investigated using strains defective in the two membrane-bound nitrate reductases, and also defective in either ubiquinone or menaquinone biosynthesis. The data reveal that Nap is coupled more effectively to menaquinol oxidation than to ubiquinol oxidation. Conversely, parallel experiments with a second set of mutants revealed that nitrate reductase A couples more effectively with ubiquinol than with menaquinol. Three further sets of strains were constructed with combinations of in frame deletions of ubiCA, menBC, napC, napF and napGH genes. NapF, NapG and NapH were shown to play no role in electron transfer from menaquinol to the NapAB complex but, in the Ubi+Men- background, deletion of napF, napGH or napFGH all resulted in total loss of nitrate-dependent growth. Electron transfer from ubiquinol to NapAB was totally dependent upon NapGH, but not on NapF. NapC was essential for electron transfer from both ubiquinol and menaquinol to NapAB. The results clearly established that NapG and H, but not NapF, are essential for electron transfer from ubiquinol to NapAB. The decreased yield of biomass resulting from loss of NapF in a Ubi+Men+ strain implicates NapF in an energy- conserving role coupled to the oxidation of ubiquinol. We propose that NapG and H form an energy- conserving quinol dehydrogenase functioning as either components of a proton pump or in a Q cycle, as electrons are transferred from ubiquinol to NapC.     

Mature rat testis contains a high molecular weight species of phosphatidylinositol transfer protein

Immunoblot analysis of a rat testis cytosol fraction revealed two proteins which reacted with a polyclonal rabbit antibody to bovine phosphatidylinositol transfer protein. These two proteins were separated by anion exchange and molecular sieve column chromatographic procedures and shown to catalyze the transfer of phosphatidylinositol and phosphatidylcholine between populations of small unilamellar vesicles. One protein was identified as the phosphatidylinositol transfer protein detectable in 16 other rat tissues and many eukaryotic species; the other phosphatidylinositol transfer protein was unique to testis. The molecular masses of the proteins, determined under denaturing electrophoretic conditions, were 35 and 41 kDa, respectively. When testis was examined in animals from birth to six weeks of age, the 35-kDa protein was present throughout, while the 41-kDa protein first appeared during week 4 and increased to adult levels by week 6; a small yet significant increase in tissue phosphatidylinositol transfer activity accompanied this expression of the testis-specific protein. Selective destruction of Leydig cells by ethylene dimethanesulfonate did not cause any detectable loss of the 41-kDa phosphatidylinositol transfer protein. The structural and catalytic relationships between the two testicular phosphatidylinositol transfer protein species remain to be elucidated.     

Reconstructing the evolution of genes along the species tree

A model and algorithm are proposed to infer the evolution of a gene family described by the corresponding gene tree, with respect to the species evolution described by the corresponding species tree. The model describes the evolution using the new concept of a nested tree. The algorithm performance is illustrated by the example of several orthologous protein groups. The considered evolutionary events are speciation, gene duplication and loss, and horizontal gene transfer retaining the original gene copy. The transfer event with the loss of the original gene copy is considered as a combination of gene transfer and loss. The model maps each evolutionary event onto the species phylogeny.     

Leucine: tRNA Ligase from Cultured Cells of Nicotiana tabacum var. Xanthi: Evidence for de Novo Synthesis and for Loss of Functional Enzyme Molecules

Leucine:tRNA ligase was assayed in extracts from cultured tobacco (Nicotiana tabacum) XD cells by measuring the initial rate of aminoacylation of transfer RNA with l-[4,5-³H]leucine. Transfer RNA was purified from tobacco XD cells after the method of Vanderhoef et al. (Phytochemistry 9: 2291-2304). The buoyant density of leucine:tRNA ligase from cells grown for 100 generations in 2.5 mm [¹⁵N]nitrate and 30% deuterium oxide was 1.3397. After transfer of cells into light medium (2.5 mm [¹⁴N]nitrate and 100% H₂O) the ligase activity increased and the buoyant density decreased with time to 1.3174 at 72 hours after transfer. It was concluded that leucine:tRNA ligase molecules were synthesized de novo from light amino acids during the period of activity increase. The width at half-peak height of the enzyme distribution profiles following isopycnic equilibrium centrifugation in caesium chloride remained constant at all times after transfer into light medium providing evidence for the loss of preexisting functional ligase molecules. It was concluded that during the period of activity increase the cellular level of enzyme activity was determined by a balance between de novo synthesis and the loss of functional enzyme molecules due to either inactivation or degradation.