The removal index for evaluation of dialysis

OBJECTIVES

To find an index of adequacy that takes into consideration the effect of the decreasing concentration of urea nitrogen in hemodialysis (HD) and can be used before treatments to quantitate the prescriptions with the same criterion for both HD and continuous ambulatory peritoneal dialysis (CAPD).

DESIGN

The removal index was obtained through mathematical theories and then compared with the urea index (KT/V) values of the sample patients.

PATIENTS

Thirty-two HD and 21 CAPD patients were included. All patients were dialyzed with optimal urea index values and had been stable for at least one year.

RESULTS

The removal index in HD (xi HD) for each dialysis was O.62 +/- 0.07, and the normalized removal index in CAPD (xi CAPD) was 0.59 +/- 0.11. There was no statistical significance. This result is consistent with the fact that no difference of morbidity or mortality exists between these two modalities.

CONCLUSION

After mathematical manipulation, the removal index in HD can be presented in the form of the urea reduction ratio, which is a retrospective measure to estimate the performance of hemodialysis. This study implies that the removal index is able to facilitate the prescriptions for adequate dialysis. The removal index can also be used to explain the reason why the urea index values are always larger in HD than in CAPD.

The physiological effect of CO2 pneumoperitoneum in pediatric laparoscopy

BACKGROUND

The physiological effect of CO2 pneumoperitoneum during laparoscopy is a great concern of the anesthesiologists. Its effect in pediatric laparoscopy has not been previously reported. The purpose of this study was to examine the physiological alteration of pediatric patients during CO2 pneumoperitoneum.

METHODS

One hundred and twenty six children aged from 11 mon to 13 yr undergoing laparoscopic inguinal exploration were divided into three groups based on age orientation: group I comprising 40 children with age from 11 mon to 2 yr; group II 46 children with age between 2 to 5 yr; and group III 40 children aged from 5 to 13 yr. All patients received endotracheal anesthesia with halothane-N2O in 50% O2 and atracurium for muscle relaxation. Respiration was controlled by an Ohmeda 7000 ventilator with constant minute ventilation to maintain baseline end-tidal CO2 tension (PETCO2) between 32-33 mmHg. After anesthesia, CO2 was insufflated into the peritoneal cavity via the opened hernia sac. The intraabdominal pressure exerted by CO2 was 10 mmHg and the duration of pneumoperitoneum and laparoscopy was 15 min. We recorded airway pressure, PETCO2, body temperature, blood pressure, heart rate, heart rhythm, and oxygen saturation simultaneously at 1 min interval before, during, and after laparoscopy.

RESULTS

The airway pressure and PETCO2 showed significant increases during laparoscopy (15-18% and 18-20% respectively) in all cases, but the percentage of increases were not significantly different among groups. However, the PETCO2 change in terms of time lag were different between groups: (1) the time lag from CO2 insufflation to the emergence of PETCO2 change (latent period) was respectively 0.7 +/- 0.1 (mean +/- SD) min in group I, 0.9 +/- 0.2 min in group II and 1.5 +/- 0.2 min in group III (p < 0.05); (2) the PETCO2 change from baseline to a plateau (ascending period) was respectively 4.2 +/- 0.6 min in group I, 6.3 +/- 1.0 min in group II and 9.1 +/- 1.1 min in group III (p < 0.05); (3) the PETCO2 decline from plateau to baseline after CO2 deflation (descending period) was respectively 6.2 +/- 0.5 min in group I, 8.3 +/- 0.8 min in group II and 12.0 +/- 1.3 min in group III (p < 0.05). The body temperature and hemodynamics including blood pressure, heart rate, heart rhythm, oxygen saturation were not significantly changed during laparoscopy in all groups.

CONCLUSIONS

The changes of PETCO2 during laparoscopy did not influence the hemodynamic stability in our study. The younger children give a faster reaction time of PETCO2 change after CO2 insufflation than do the older children which may be related to the variation of physiological exhibition at different state of development.

Iron metabolism indices for early prediction of the response and resistance to erythropoietin therapy in maintenance hemodialysis patients

A prospective study with 65 maintenance hemodialysis (MHD) patients on recombinant human erythropoietin (rHuEPO) therapy was conducted to assess the effect of iron balance on responsiveness. An attempt to define the predictors of erythropoietin (EPO) response and identify the specific causes of EPO resistance was undertaken in the present study. The treatment protocol consisted of two stages, the first was rHuEPO therapy for 6 months and the second was iron supplementation plus rHuEPO therapy in patients without response to EPO for the next 6 months. According to the hemoglobin (Hb) changes (increment exceeded 30% of baseline or did not exceed 15% of baseline for 3 consecutive months) and whether or not there was an achievement of target Hb level (>10.5 g/dl), all patients (n = 65) were divided into EPO-responsive (n = 20) and EPO-resistant (n = 45) groups. The EPO-resistant patients were then further stratified into iron-responsive (n = 29) and iron-irresponsive (n=16) groups. Iron metabolism and red cell indices were analyzed prior to and following rHuEPO therapy and iron supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Total paracentesis in non-alcoholic cirrhotics with massive ascites: mid-term effects on systemic and hepatic haemodynamics and renal function

Single total paracentesis (4.8-11 L) was performed in 23 patients with hepatitis B surface antigen (HBsAg)-positive cirrhosis and massive ascites and its effects on systemic and hepatic haemodynamics and renal function were examined over 5 days. Severe hypotension occurred in six (26.1%) patients from 6 to 54 h after paracentesis. In the remaining 17 patients, compared to the baseline, there was an increase in the cardiac output (6.1 +/- 0.3 vs 6.7 +/- 0.3 L/min, P < 0.001) and a decrease in right atrial pressure (8.8 +/- 0.8 vs 4.3 +/- 0.7 mmHg, P < 0.001), systemic vascular resistance (1160 +/- 61 vs 976 +/- 50 dyne.s.cm-5, P < 0.001), and wedged hepatic venous pressure 30 min after completion of paracentesis. After 5 days, right atrial pressure, systemic vascular resistance and wedged hepatic venous pressure returned to baseline, while the cardiac output dropped to a level lower than the baseline (5.7 +/- 0.7 L/min, P < 0.05). Hepatic venous pressure gradient had returned to baseline after 5 days. Serial tests of serum creatinine level showed an increase from day 3 (1.34 +/- 0.14 vs 1.04 +/- 0.10 mg/dL, P < 0.05). On day 5, creatinine clearance (55.7 +/- 5.4 vs 41.9 +/- 5.3 mL/min, P < 0.05) and effective renal plasma flow (351 +/- 32 vs 293 +/- 29 mL/min, P < 0.05) were decreased, compared to the baseline. Based on these data, infusion of a volume expander may be necessary for total paracentesis to avoid systemic haemodynamic complications in non-alcoholic cirrhosis.

Mucopolysaccharide histochemistry of the oviduct of the toad, Bufo melanostictus, before and during ovulation

In both non-ovulating and ovulating toads of the species, Bufo melanostictus, the fimbrium stained only weakly for mucopolysaccharides (MPs) whereas the infundibulum stained strongly for neutral MPs and also for glycogen. In the non-ovulating toad, only neutral and sulphated MPs were detected in the goblet cells of the upper magnum, whereas sulphated, neutral and sialomucins were detected in the glands. In the middle magnum, sulphated and sialic acid-containing carboxylated MPs were detected in both the goblet cells and glands. In the lower magnum, neutral, sulphated, and sialic acid-containing MPs were detected in the goblet cells and only sulphated and sialic acid-containing MPs were detected in the glands. In the isthmus and ovisac, only sulphated MPs were present in the goblet cells. During ovulation, there was no change in the distribution of sulphated MPs throughout the oviduct. Sialic acid-containing MPs could not be detected in many of the goblet cells of the upper and lower magnum nor in most of the glands of the lower magnum.

Simple formula for light scattering by a large spherical dielectric

The generalized eikonal equation for light scattering by a dielectric sphere obtained earlier is further studied. It is found that all the integrals in the equation can be carried out, and the result is a simple algebraic formula for the scattering amplitude. The formula provides a quick way to compute the intensity of scattered light and brings about deeper physical insights of the scattering processes.

A scanning electron microscopic study of the oviduct of the toad, before and during ovulation

The surface features of the oviduct of the toad, Bufo melanostictus, was studied under the scanning electron microscope. The epithelial folds show regional variations, being longitudinally disposed in the upper part of the oviduct, spirally arranged in the middle and convoluted in the lower part. There is an abundance of cilia through the oviduct except in the ovisac. Goblet cells are interspersed among the epithelial cells. In between the epithelial folds are openings of tubular secretory glands. During ovulation, there is patchy loss of cilia throughout the oviduct. Most of the goblet cells are empty. On the surface, the cilia are matted together by secretory material which are laid down in layers.

Peritoneal transfer during maximal hyperosmotic ultrafiltration in the rat

Peritoneal transfer parameters were estimated in rats (n = 24) while maximal net ultrafiltration rate (nUFR) was achieved with 15% dextrose dialysis solution (1,153 mOsm/kg) and compared with those obtained with 0.37% dextrose solution (301 mOsm/kg). Experiments were carried out with dialysis solutions of pH approximately 6.5 and approximately 7.6, respectively, for 15% dextrose dialysis solution and 0.37% dextrose solution. Increases in both convective and diffusive transfer resulted in more than 70% greater peritoneal clearances of urea, potassium, and phosphate with hyperosmotic solutions at both pH values. Protein removal was increased only with a hyperosmotic solution of pH approximately 6.5 compared with isosmotic conditions at the same pH. Results support the hypothesis that increased peritoneal transfer parameters under hyperosmotic conditions depend not only upon enhanced convection but also on factors promoting diffusive transfer.

Large-angle light scattering at large size parameters

The generalized eikonal amplitude for light scattering at large size parameters by a dielectric sphere is modified to account more rigorously for the phase-change difference caused by the presence of the medium. The resulting amplitude is shown to work well for scattering at large angles. It accurately predicts the positions of maxima and minima for scattering angles up to 60 degrees for perpendicularly polarized light.

Peritoneal transfer of carbon dioxide in the rat

In the authors' previous rat studies (Kidney Int 39: 608-617, 1991), peritoneal clearances (Cp) representing near exclusively diffusive CO2 transfer were evaluated: for isosmotic (0.37% dextrose) and hyperosmotic (15% dextrose) solutions with pH 7.2-7.3, Cp CO2 were 1.20 +/- 0.08 and 1.84 +/- 0.04 ml/min, respectively. In the present studies peritoneal transfer parameters (D/B, Cp) of CO2 gas, HCO3-, and total CO2 (tCO2) in anesthetized rats have been compared (n = 22) using solutions with dextrose contents as mentioned above but with a pH of 6.5 or 7.6; how much Cp CO2 measurements obtained with solutions at these pH values differ from Cp shown earlier with solutions of pH 7.2-7.3 has also been evaluated. When the pH was the same, transfer parameters of CO2 gas, HCO3-, and tCO2 were significantly higher under hyperosmotic conditions. The use of solutions with a pH different from 7.2-7.3 resulted in higher Cp of CO2 gas: with isosmotic solutions at pH 6.5 and 7.6, mean increases were 25 and 75%, respectively; with hyperosmotic solutions respective increases were 45 and 134%. The authors conclude that dialysis solution pH, especially under hyperosmotic conditions, significantly changes parameters of diffusive CO2 transfer in the rat. For evaluation of peritoneal blood flow from diffusive transfer parameters of CO2 gas, smaller overestimation can be expected when dialysis solution pH is slightly under than overadjusted compared to blood pH.

A scanning and transmission electron microscopic study of the membranes of chicken egg

Questions regarding the structure of the inner and outer shell membranes of the chicken egg were addressed in this study by correlating observations from light microscopy and scanning and transmission electron microscopy. The egg membrane had a limiting membrane, which measured .9 to .15 microns in thickness and appeared to be a continuous and an impervious layer, but the shell membrane did not. Under the SEM, each membrane was seen to be made up of several fibre layers. In the tear preparations viewed under the SEM two layers were observed in the egg membranes and three to five layers in the shell membrane, with an apparent plane of cleavage between each layer. Each fibre was made up of a central core and an outer mantle layers. The central core was perforated by channels which measured .08 to 1.11 microns in diameter and ran longitudinally along the length of the fibre. Between the mantle layer and the fibre core was a gap or cleft measuring between .03 to .07 microns. The diameter of the fibres of the inner layer of the egg membrane ranged between .08 to .64 microns, whereas those of the outer layer of the same membrane ranged from .05 to 1.11 microns. Fibres in the shell membrane ranged from .11 to 4.14 microns diameter.

Spurious hyperchloremia and decreased anion gap in a patient with dextromethorphan bromide

Although cold syrup containing dextromethorpan bromide is widely administered, the bromism due to cold syrup has not been reported. We report a patient who had negative anion gap with hyperchloremia and conscious loss because of daily intake of cold complex syrup (containing dextromethorphan bromide 0.4 mg/ml, acetaminophen 8.33 mg/ml) for headache for 4-5 years. The bromide content in cold complex syrup resulted in serum levels of bromide that interfered with the automated analyzers for chloride content. When conscious change is due to bromism, hemodialysis instead of forced hydration and diuresis should be performed immediately. Therefore, patients with a markedly negative anion gap with hyperchloremia should be considered as having halide intoxication.

Peritoneal clearances of carbon dioxide in the rat

In our previous rat studies (Kidney Int. 1991; 39: 608-617) we evaluated peritoneal clearances (Cp) representing near exclusively diffusive CO2 transfer: for isosmotic (0.37% dextrose) and hyperosmotic (15% dextrose) solutions with pH 7.2-7.3, CpCO2 were 1.20 +/- 0.08 and 1.84 +/- 0.04 ml/min, respectively. In the present studies we have compared Cp of CO2 gas and HCO3- in anesthetized rats (n = 22) using solutions with dextrose contents as mentioned above but with pH 6.5 or 7.6; we have also evaluated how much Cp CO2 measurements obtained with solutions at these pH values differ from Cp shown earlier with the solutions of pH 7.2-7.3. Cp of CO2 gas and HCO3- were significantly higher under hyperosmotic than isosmotic conditions. The use of solutions of pH different from 7.2-7.3 resulted in higher Cp of CO2 gas: with isosmotic solutions of pH 6.5 and 7.6 mean increases were 25 and 75%, respectively; with hyperosmotic solutions respective increases were 45 and 134%. We conclude that dialysis solution osmolality and pH significantly change Cp of CO2 gas and HCO3- in the rat. For evaluation of peritoneal blood flow from diffusive transfer parameters of CO2 gas, smaller overestimation can be expected when dialysis solution pH is slightly under-than overadjusted compared to blood pH.

Sieving and reflection coefficients for sodium salts and glucose during peritoneal dialysis in rats

The two-part studies reported herein address peritoneal membrane ultrafiltrate (UF) characteristics during peritoneal dialysis exchanges in rats. In the studies of part 1, the sieving coefficients for sodium, chloride, and total solutes during hydrostatic UF after instillation of rat serum into the peritoneal cavity of rats were calculated. Thirty-six rats were divided into six groups (N = 6) according to the following peritoneal dialysis exchange cycle times: 60, 120, 180, 240, 480, and 960 min. Thirty milliliters of pooled rat serum were infused i.p. with the animal being conscious except during infusion and drainage. The study showed in the early phase of exchanges, when oncotic and osmotic pressure gradients were absent, net UF presumably due to capillary hydrostatic pressure and sodium sieving during such UF. Sieving coefficients for sodium (0.72), chloride (0.77) and total solutes (0.73) were determined by using standard formulae. In the second part of these studies, the kinetics of fluid movement after the instillation of 5% dextrose solution into the peritoneal cavity of rats were analyzed. A very low UF rate was observed early in the exchange when the glucose gradient between the dialysis solution and blood was at its peak. The UF rate gradually increased as the sodium entered the dialysis solution from the blood. At the time of low UF rate with high glucose gradient, presumably the osmotic pressure generated by the glucose in the dialysis solution was countered by the osmotic pressure of solutes in plasma, i.e., sodium and its anions.(ABSTRACT TRUNCATED AT 250 WORDS)

[In vitro cytotoxicity of Ganoderma lucidum on oral cancer cells]

The extract from the mycelium of Ganoderma lucidum was diluted into serial concentrations and added into in vitro cultured oral cancer and normal cell lines. After incubation for 24 hours, the survival fraction was determined by MTT colorimetric assay. The result revealed that the ID50 was about 3mg/ml and the total lethal dosage was beyond 4 mg/ml. This toxic effect was the same in both cancer and normal cells. Not only was there no difference between cancer and normal cells, but also the high dosage required in toxicity leads to the conclusion that the GL has no direct cytotoxic effect in cancer treatment.

Ultrafiltration and effective peritoneal blood flow during peritoneal dialysis in the rat

The dependence between maximum net ultrafiltration rate (nUFR) created by 15% dextrose dialysis solution and effective peritoneal capillary blood flow (EPBF) estimated by the diffusive mass transport coefficient (KBD) and peritoneal clearance (Cp) of CO2 gas was evaluated during 30 minute, 15 ml peritoneal dialysis exchanges in anesthetized rats (N = 18). The values of KBD for CO2 suggested a mean EPBF of 1.9 +/- 0.1 (SEM) ml/min for isosmotic exchanges and 2.7 +/- 0.2 ml/min for hyperosmotic ones with a mean maximum nUFR of 0.43 +/- 0.01 ml/min. Cp of CO2 measured after the first five minutes of dwell underestimated EPBF. In normally hydrated rats, maximum nUFR was achieved when the peritoneal filtration fraction was 32 +/- 2%. This value is similar to the glomerular filtration fraction in rats of 30%. Thus, our results indicate the following relationships: EPBF = (approximately 3 x maximum nUFR)/(1 - hematocrit). EPBF was about six times greater than maximum nUFR and exceeded about 57 times nUFR obtained under isosmotic conditions. These differences between EPBF and nUFR suggest normal EPBF is not a major limiting factor for maximum ultrafiltration achieved during peritoneal dialysis.

Renal excretion of oxalate in patients with chronic renal failure or nephrolithiasis

This study was carried out in order to investigate renal oxalate excretion in a group of normal subjects (n = 40), a group of patients with uremia (n = 52) and a group with nephrolithiasis (n = 34). We found that the mean concentrations of oxalate in the 24-hour urine specimens of both patient groups were below the normal range. Although the renal creatinine clearance (CCR) was significantly decreased in some stone patients (n = 14), decreased renal oxalate clearance was noted only in those patients with severe renal failure. Thus, plasma oxalate was found to be elevated only in patients with chronic renal failure (mean +/- SD, 49.7 +/- 12.4 mumol/l), while the normal value was 17.0 +/- 6.7 mumol/l. The mean tubular excretion fraction of oxalate was also found to increase markedly in uremia with a mean of 26.3 +/- 17.3% (in normal subjects, 11.7 +/- 7.5%), but their mean daily urinary excretion of oxalate decreased to 63.2 mumol/day (mean value of 232.6 mumol/day in normal subjects). A positive correlation was observed between oxalate and creatinine, and between oxalate and calcium excretion, which was not found in normal subjects or patients with kidney stones. In nephrolithiasic patients, the daily excretion of oxalate, calcium and phosphate had no discernible increment and the mean excretory ratio of oxalate, calcium or phosphate to creatinine was all within normal limits. But when the CCR of stone patients was below 80 ml/min, their daily excretion of oxalate and calcium decreased significantly (p less than 0.01) and the excretory ratio of phosphate to creatinine markedly increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Modified P-Q plot of light scattering for large size parameters

A new plot for the forward-scattering amplitude in the complex domain is proposed. The plot graphs the imaginary part versus the real part with the edge effects properly subtracted. Interesting features of the new plot are discussed for light scattering by a dielectric sphere.

Renal excretion of zinc in patients with chronic uremia

Though uremic patients have been reported to have subnormal zinc levels in plasma and an abnormal zinc metabolism, data on their renal excretion of zinc are still unavailable. In our study, 55 nondialyzed uremic patients had a markedly lower concentration of zinc in plasma and a lower urinary zinc excretion. They had a higher excretory fraction of zinc in the renal tubules and a higher ratio of zinc to creatinine excretion than normal subjects. We found that the total daily excretion of zinc, calcium, phosphate and ammonia was reduced, and that the ratio of calcium or ammonia to creatinine excretion decreased in uremic patients. Urinary zinc excretion was correlated with renal creatinine clearance (r = 0.50, p less than 0.001) in both normal subjects and uremic patients, but ammonia excretion was correlated with zinc excretion in normal subjects only. In uremia, urinary zinc excretion was correlated with urinary calcium (r = 0.55, p less than 0.001) and urinary phosphate excretion (r = 0.30, p less than 0.05). We conclude that the increased ratio of zinc to creatinine excretion and the excretory fraction of zinc in the renal tubules of uremic patients may increase the urinary zinc excretion, but a severe diminution of the glomerular filtered load of zinc may be the major factor in decreasing the urinary zinc excretion in uremia.

High energy light scattering in the generalized eikonal approximation

The generalized eikonal approximation method is applied to the study of light scattering by a dielectric medium. In this method, the propagation of light inside the medium is assumed to be rectilinear, as in the usual eikonal method, but with a parameterized propagator which is used to include the edge effect and ray optics behavior at the limit of very short wavelengths. The resulting formulas for the intensity and extinction efficiency factor are compared numerically and shown to agree excellently with the exact results for a homogeneous dielectric sphere.

Interzeta-globin gene hypervariable regions in Chinese: application to genetic diagnosis of adult polycystic kidney disease

In order to investigate the interzeta-globin gene hypervariable regions (IZHVR) in Chinese, DNA samples from 114 unrelated normal individuals were analyzed using the restriction endonuclease BglII and hybridized with a 32P-labeled zeta-globin probe. Four polymorphic fragments containing IZHVR with different frequencies were found: 11.3 kb, 0.24; 10.8 kb, 0.50; 10.4 kb, 0.05, and 10.0 kb, 0.21. Using these polymorphic fragments as linkage markers, we were able to trace the affected siblings in a three-generation Chinese family with a history of adult polycystic kidney disease.

A New UV-A/B Protecting Pigment in the Terrestrial Cyanobacterium Nostoc commune

A new ultraviolet (UV)-A/B absorbing pigment with maxima at 312 and 330 nanometers from the cosmopolitan terrestrial cyanobacterium Nostoc commune is described. The pigment is found in high amounts (up to 10% of dry weight) in colonies grown under solar UV radiation but only in low concentrations in laboratory cultures illuminated by artificial light without UV. Its experimental induction by UV as well as its capacity to efficiently protect Nostoc against UV radiation is reported.

Pancreatic enzymes in uremic patients with or without dialysis

One hundred thirty blood samples from 87 patients with renal failure, but without abdominal pain, were analyzed for blood urea nitrogen (BUN), creatinine, amylase, p-isoamylase, and lipase simultaneously. We found that 74, 78, and 80% of the patients had hyperamylasemia, hyperisoamylasemia, and hyperlipasemia. None had amylase higher than five times the upper limit. A few patients (2.3%) had lipase elevated to more than 10 times the upper limit. No significant change of pancreatic enzyme level was noted as a result of hemodialysis, but a significant amount of amylase was removed from the circulation in patients receiving intermittent peritoneal dialysis. Significantly lower pancreatic enzyme levels were observed in patients with less impairment of renal function. We conclude that elevation of pancreatic enzymes in uremic patients is more frequent and more extensive than most articles indicate, and that the extent of increase is related more to renal function than to the modalities of dialysis the patients received.

Scattering of light by a stratified sphere in high energy approximation

Glauber's approximation method valid at high energy is used to study light scattering by a stratified sphere. The scattering amplitude is obtained in a simple closed form. The resulting efficiency factors and intensities of the scattered light are numerically evaluated for dielectric bubbles and wet dielectric balls and are shown to agree well with the exact values from Mie's method.

Activities of fatty acid desaturases and fatty acid composition of liver microsomes in rats fed beta-carotene and 13-cis-retinoic acid

The fatty acid composition of microsomal lipids and the activities of delta 9- and delta 6-desaturases in liver microsomes of rats fed diets supplemented with beta-carotene and two levels of 13-cis-retinoic acid were studied. Four groups of male, weanling rats were fed semipurified diets containing 0 or 100 mg beta-carotene per kg diet, and 20 or 100 mg 13-cis-retinoic acid per kg diet. After 11 weeks of feeding, the rats were killed, liver microsomes were prepared and assayed for delta 9-desaturase and delta 6-desaturase activities. The activity of delta 9-desaturase was lower in liver microsomes of rats fed beta-carotene-supplemented diet or the diet supplemented with the higher level of 13-cis-retinoic acid. Microsomal delta 6-desaturase activity was, however, higher in liver of rats fed 13-cis retinoic acid; there was no effect of beta-carotene on delta 6-desaturase activity. The fatty acid compositional data on total lipids of liver microsomes were consistent with the diet-induced changes in fatty acid desaturases. Phospholipid composition of liver microsomes was also altered as a result of feeding beta-carotene or 13-cis-retinoic acid-containing diets. The proportions of phosphatidylethanolamine were generally higher, whereas those of phosphatidylcholine were lower in the experimental groups as compared with the control.

Effect of probenecid on the pharmacokinetics of aminophylline

The authors investigated the effect of probenecid on the pharmacokinetics of aminophylline. Seven normal volunteers served as their own controls in a crossover study. In the first phase, subjects received an oral dose of aminophylline after an overnight fast. In the second phase, probenecid was given orally 30 minutes prior to the administration of aminophylline. Serum and urine theophylline levels were determined by high performance liquid chromatography. Statistical analysis showed that probenecid had no significant effect on any of the pharmacokinetic parameters measured. Probenecid appears to have little or no influence on the liver metabolism of theophylline.

THE EFFECT OF A SYNTHETIC OXYTOCIN UPON THE INTRAMAMMARY PRESSURE OF DAIRY COWS

The effect of a synthetic oxytocin (CIBA) on the intramammary pressure (I.M.P.) of dairy cows was studied by the use of a polygraph equipped with a pressure transducer. The I.M.P. of each quarter of the udder was found to be 19 to 20 mm Hg before milking and 11.5 to 12.5 mm Hg after milking. Intravenous injection of oxytocin (25 I.U.) caused an increase of 95% in I.M.P. prior to milking and an increase of only 18% after milking.

MECHANICAL AND ELECTRICAL ACTIVITIES OF THE FEMALE BOVINE GENITAL TRACT IN VIVO

The mechanical activity of the female bovine genital tract, as measured by a Statham transducer, was greatest during estrus and declined during non-estrus. With advancing pregnancy the frequency of the contractions gradually decreased and the amplitude increased.Measurement of electrical activity, by attaching electrodes to various parts of the body and recording the bioelectric potentials of the tract, showed a close relationship to the mechanical activity when both were recorded simultaneously in vivo. In both cases recordings were made on a GME M5P polygraph.Oxytocin enhanced both the electrical and the mechanical activities of the tract.