[Concentration of sulbenicillin in human serum and myocardial tissue]

The concentration of sulbenicillin in the serum and myocardial tissue of 13 patients were determined at cardiac surgery. About 100 mg/kg of sulbenicillin were administered intravenously for 60 minutes. Right auricle resected at the vena caval cannuration was examined for myocardial tissue. The serum concentration was also examined every 30 minutes after injection, 30 minutes, 60 minutes, 90 minutes, 120 minutes and 150 minutes. Mean values of serum concentration were 213.6 micrograms/ml, 432.5 micrograms/ml, 181.6 micrograms/ml, 236.3 micrograms/ml and 101 micrograms/ml, respectively. The values determined in myocardial tissue were 146.5 micrograms/g (60 minutes), 39.2 micrograms/g (90 minutes), 66.0 micrograms/g (120 minutes) and 23.5 micrograms/g (150 minutes). The mean value of concentration ratio of sulbenicillin in myocardial tissue was 0.23 of serum concentration. The high myocardial tissue levels of sulbenicillin suggests that its use at cardiovascular surgery would protect the myocardial tissue from the bacterial infections.

Conversion of low density lipoprotein 1 (LDL1, 1.019 less than d less than 1.045) to low density lipoprotein 2 (LDL2, 1.045 less than d less than 1.063) by hepatic triglyceride lipase

The role of lipoprotein lipase and hepatic lipase in the conversion of LDL1 (1.019 less than d less than 1.045) to LDL2 (1.045 less than 1.063) were investigated on the basis of incubation of 125I-LDL1 with postheparin plasma (PHP) at NaCl concentrations of both 0.15 M and 1.0 M. Insignificant small increments of radioactivity and apoprotein B specific activity of LDL2 were observed even when 125I-LDL1 was incubated with preheparin plasma as the control. When 125I-LDL1 was incubated with PHP, the LDL1 radioactivity decreased and the LDL2 radioactivity increased significantly. the apoprotein B specific activity was also increased in the LDL2 fraction. One molar NaCl did not inhibit these changes. It is concluded that hepatic triglyceride lipase was the major mediator in the conversion of LDL1 to LDL2.

Brain tumor evaluation using Rb-82 and positron emission tomography

Positron emission tomography of the brain with 75-sec rubidium-82 obtained from a portable generator (25-day Sr-82 leads to Rb-82) was used to evaluate the integrity of the blood-brain barrier (BBB) in patients with brain tumors. Rubidium is normally excluded from the central nervous system by the intact BBB, but when the BBB is disrupted by a tumor. Rb enters and pools in the extravascular spaces of the central nervous system. Since Rb is also rapidly cleared from the blood, a high tissue-to-blood ratio of the Rb-82 tracer is achieved in regions of BBB disruption after intravenous injection. With dynamic positron emission tomographic imaging, the extravasation of the Rb tracer can be evaluated independent of the intravascular Rb concentration, and very small changes in the BBB permeability can be detected. The results of our studies in eight patients show that this technique is a promising method for evaluation of the BBB integrity in brain-tumor patients.U

Preparation of 11C-methyl iodide and L-[S-methyl-11C]methionine by an automated continuous flow process

A continuous flow procedure has been developed for the synthesis of 11C-methyl iodide and L-[S-methyl-11C]methionine from 11CO2. The preparation can be completed in 20 min after the end of bombardment. This procedure results in the production of approximately 44 mCi 11C-methyl methionine with a specific activity of 3.3 Ci/mmol. Radiochemical purity is greater than 96%. The procedure has been automated so that the preparation can be carried out remotely, thus minimizing exposure of personnel to radiation.

A precision flow-controlled Rb-82 generator for bolus or constant-infusion studies of the heart and brain

A precision flow-controlled rubidium-82 generator has been constructed to deliver 76-sec Rb-82 at either fast or slow flow rates for bolus or constant-infusion studies. A stepping motor drive is interfaced to a microprocessor for pulsed control of flow rate to deliver the saline eluant solution from a large-volume (150 ml) machined pumping syringe through an alumina column that retains the 25-day Sr-82 parent. The generator system delivers 70-90% of the maximum Rb-82 activity in a 20-25 ml bolus elution of 2% NaCl. The Sr-82/Sr-85 breakthrough is 10(-7) - 10(-6). both yield and breakthrough are functions of column length and flow rate. Six separate Sr-82 loadings of the generator were evaluated over a period of nearly 2 yr in studies of myocardial blood perfusion and permeability changes in the blood-brain barrier. Sterility and apyrogenicity of the Rb-82 eluate were maintained during multiple elutions and long-term use of 3-4 mo for each generator loading.

Recovery of sliding ability in arm-depleted flagellar axonemes after recombination with extracted dynein I

We compared sliding velocity between outer doublet tubules in demembranated axonemes of sea-urchin (Pseudocentrotus depressus) sperm flagella with that of arm-depleted axonemes recombined with extracted dynein I. The outer arm-depleted axonemes after extraction with 0.5 M NaCl had a velocity of 6.9 +/− I.0 micrometer/s, while the intact axonemes had a velocity of 14.3 +/− I.5 micrometer/s in the presence of I mM ATP and 2 microgram/ml trypsin at 25 degrees C. The sliding velocity was closely related to the number of remaining outer arms following the NaCl-extraction process. When the outer arm-depleted axonemes were recombined with dynein I, the sliding velocity increased to 11.3 +/− 1.3 micrometer/s. Electron microscopy confirmed the recovery of 94% of outer arms in the axonemes. After extraction with Tris-EDTA solution for 10 min, the axonemes lost their sliding ability completely, even in the presence of ATP and trypsin. Such axonemes lacked most of both inner and outer arms, although sometimes the basal segment of the arms appeared to remain. When the exogenous dynein I fraction extracted from other axonemes was added, the axonemes could extrude tubules, and both types of arms reappeared clearly and distinctly in the axonemes. The recombined axonemes with one-fold stoichiometric excess of dynein I recovered 58% of the total number of arms and had a velocity of 7.4 +/− 1.6 micrometer/s. Those with 2-fold stoichiometric excess had a velocity of 11.0 +/− 1.5 micrometer/s, up to 82% of the arms in these axonemes being restored. These results indicated that the exogenous dynein I fraction derived from the outer arms restored sliding ability to arm-depleted axonemes, recombining with th outer doublet tubules as inner and outer arms, and that the sliding velocity had a close relationship to the total number of arms in the axonemes, irrespective of their being inner or outer arms.

Sliding velocity between outer doublet microtubules of sea-urchin sperm axonemes

Using a dark-field microscope equipped with a high-efficiency TV camera including a video tape-recorder, we recorded the sliding movement between outer doublet microtubules of the demembranated axonemes of sea-urchin (Pseudocentrotus depressus and Hemicentrotus pulcherrimus) sperm flagella by adding ATP and trypsin at 25 degrees C. The time and length of the sliding doublet microtubules from axonemes were measured directly from the image on the picture monitor from the video tape. The sliding velocity was almost constant in the range from 0 to 2% polyethylene glycol concentration in the reactivation medium and decreased a little at more than 2%. We prepared various lengths of axoneme fragments by homogenizing whole axonemes and found that the shorter fragments showed similar sliding velocity to that of longer ones at less than 200 microM ATP, but slightly decreased speed at more than 500 microM. ATP. The sliding movement sometimes stopped and the percentage of sliding axonemes was lower below 2 micrograms/ml trypsin. Above 3 micrograms/ml, the process appeared to be more like disintegration than sliding movement, which may be due to excess digestion by trypsin. Sliding speed was therefore measured in a reactivation medium containing 2% polyethylene glycol with the addition of ATP and 2 micrograms/ml trypsin. The velocity increased in proportion to the increase in ATP concentration. Vmax was approximately 14 micrograms/s at 2 mM ATP. In order to compare the Km for the sliding velocity with that of the ATPase activity of the axonemes, we measured ATPase activity of axonemes prepared and assayed under conditions in which sliding movement in the axonemes could be induced. Neither the curve of ATPase activity nor the curve of sliding velocity plotted against ATP concentration obeyed Michaelis-Menten kinetics. The close relationship between ATPase activity and sliding velocity suggested that ‘sliding-movement-coupled ATPase activity’ may well be reflected in the axoneme ATPase reported here.

ATP-driven tubule extrusion from axonemes without outer dynein arms of sea-urchin sperm flagella

We have prepared axonemes without outer dynein arms from sea-urchin (Pseudocentrotus depressus, Hemicentrotus pulcherrimus) sperm flagella by selective solubilization with NaCl. Electron microscopy revealed that the axonemes gradually lost their outer arms in 0.5 M NaCl during 10 min. Such axonemes retained 42.8 +/− 7.3% of their total axonemal ATPase activity and showed C, A, D and B bands in the dynein region of 4% SDS-gel, while a solubilized fraction of the outer arms consisted almost entirely of A band polypeptide. We have succeeded in causing extrusion of the outer doublets from such axonemes by addition of ATP and trypsin. A bundle of outer doublets was sometimes observed to be extruded first from an axoneme and to show bending motion for a while, subsequently followed by a sliding of separate doublets past each other. The speed of the tubule extrusion process was slower and around 60% of that of intact axonemes having both types of arm. These observations indicate that the inner arms have a function equivalent to that of the outer arms, of sliding on adjacent doublets, although the inner arms seem to be constituted from polypeptide(s) different from that of the outer arms.

Solubilities of water-insoluble dyes in internal water of swollen Sephadex gels

It was found that internal water of swollen Sephadex gels could dissolve appreciable amounts of water-insoluble dyes, azobenzene (AB) and dimethylaminoazobenzene (DMAB). The solubilities of AB and DMAB increased exponentially with the concentration of dextran chain in swollen Sephadex gels, i.e., plots of solubility (CG) vs. dextran-chain concentration (Cf) were well described by a family of quartic regression curves (CG=kcf4+C0,k and C0 being constants). The thermodynamic parameters pertaining to the transfer of the dyes from external water to internal water indicate that in water extensively hydrated by gel matrices, "iceberg" formation is markedly hindered and hence the hydrophobic free energy is correspondingly reduced, thereby increasing the solubilities of hydrophobic dyes. Since the solubilities of the dyes are proportional to the fourth power of the dextran-chain concentration in swollen Sephadex gels, it can be assumed that the dyes are accommodated in cooperatively hydrated water contained in unit cells made up of four dextran chains.

Thermodynamic analysis of the nonspecific interaction of sodium dodecyl sulfate with swollen Bio-Gel beads

In frontal gel chromatography on Bio-Gel P-2, sodium dodecyl sulfate (SDS) at the concentrations below its critical micelle concentration (cmc) showed anomalously high partition coefficients (Kav obs) indicative of strong interactions with the swollen gel phase; further, Kav obs was found to increase with concentration and temperature. This preferential partition of SDS in the Bio-Gel phase was analyzed in terms of the transfer free energy of SDS from the mobile phase (0.1 M NaCl) to the swollen Bio-Gel phase. The results showed that the overall transfer process is primarily governed by hydrophobic free energy arising from the anomalous nature of hydrated water in the gel matrix; that is, in highly hydrated water "iceberg" formation is evidently limited and the hydrophobic free energy is accordingly lowered, resulting in the preferential partition of SDS in the swollen Bio-Gel phase. The increase in the negativity of transfer free energy with concentration, though relatively small, indicated a definite tendency for the formation of SDS clusters in the gel phase. Finally, a model illustrating the states of SDS molecules in the gel matrix is presented, which may also be pertinent to SDS-protein and SDS-amylose complexes.