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PubMed1997

A process evaluation of condom availability in the Seattle, Washington public schools.

In 1993, Seattle began making condoms available in all of its 15 high schools. As part of an evaluation of this program, 16 focus groups with students from 13 high schools were conducted to explore students' perceptions of the school environment, program effectiveness, and suggestions for program improvement. The study also included data from a student survey conducted in 10 high schools. The focus group results revealed that students support school condom availability but have concerns about privacy when obtaining condoms. Students prefer obtaining condoms from baskets in private areas of school-based clinics to obtaining them from vending machines. Students do not believe that having condoms available has affected sexual activity or condom use among students. Recommendations for improving school condom availability include access to free condoms in private locations.

Adolescent↗

PubMed2002

Carbohydrate ingestion reduces skeletal muscle acetylcarnitine availability but has no effect on substrate phosphorylation at the onset of exercise in man.

This study investigated the effect of reduced acetylcarnitine availability on oxidative metabolism during the transition from rest to steady-state exercise. Eight male subjects completed two randomised exercise trials at 68 % of the peak rate of O(2) uptake (V((O(2)),peak)). On one occasion subjects ingested 1 g (kg body mass)(-1) glucose 75 min prior to exercise (CHO), whereas the other trial acted as a control (CON). Muscle samples were obtained pre- and 75 min post-ingestion, and following 1 and 10 min of exercise. Plasma glucose and insulin were elevated (P < 0.05), and plasma free fatty acids (FFA) were lower at the onset of exercise in CHO. Acetylcarnitine (CON, 4.8 +/- 1.8; CHO, 1.5 +/- 0.9 mmol (kg dry mass (d.m.))(-1), P < 0.05) and acetyl CoA (CON, 13.2 +/- 2.3; CHO, 6.3 +/- 0.6 micromol (kg d.m.)(-1), P < 0.05) were lower at rest, whereas pyruvate dehydrogenase activation (PDHa) was greater in CHO compared with CON (CON, 0.78 +/- 0.07; CHO, 1.44 +/- 0.19 mmol min(-1) (kg wet mass (w.m.))(-1)). Respiratory exchange ratio (RER) was significantly elevated during exercise in CHO. The acetyl groups increased at similar rates at the onset of exercise (1 min) and there was no difference in substrate phosphorylation as determined from lactate accumulation and phosphocreatine degradation between trials. Subsequently, oxidative metabolism during the transition from rest to steady-state exercise was not affected by prior carbohydrate ingestion. Although exercise resulted in the rapid activation of PDH in both trials, PDHa was greater at 1 min in CHO (CON, 2.36 +/- 0.22; CHO, 2.91 +/- 0.18 mmol min(-1) (kg w.m.)(-1)). No differences in muscle metabolite levels and PDHa were observed after 10 min of moderate exercise between trials. In summary, at rest, carbohydrate ingestion induced multiple metabolic changes which included decreased acetylcarnitine availability and small increases in PDHa. The prior changes in PDHa and acetylcarnitine availability had no effect on substrate phosphorylation and oxidative metabolism at the onset of exercise. These data suggest that acetylcarnitine availability is unlikely to be the site of metabolic inertia during the transition from rest to steady-state moderate intensity exercise.

Acetyl Coenzyme A↗

PubMed1998

Ovine fetal leucine kinetics and protein metabolism during decreased oxygen availability.

The fetus depends on an uninterrupted supply of oxygen to provide energy, not only for basal metabolism but also for the metabolic costs of growth. By curtailing the metabolically expensive processes of protein turnover, the fetus could conserve energy when oxygen availability is limited. Therefore, this investigation was performed to find whether protein synthesis and breakdown are diminished during decreased fetal oxygen availability. Furthermore, if these conditions reduce fetal growth, protein synthesis should be affected more than breakdown so that protein accretion, an important component of fetal growth, also falls. In eight chronically prepared fetal lambs, we compared leucine kinetics (reciprocal pool model) during control conditions with measurements made during maternal hypoxia, a condition that limits fetal oxygen availability. Decreased fetal oxygen availability (-43%; P < 0.001) reduced fetal oxygen consumption (-16%; P < 0.01), as well as both the uptake of leucine across the placenta (-48%; P < 0.001) and its rate of decarboxylation (-30%; P < 0.001). Fetal protein synthesis decreased (-32%; P < 0.001) to a greater extent than proteolysis (-22%; P < 0.001). Consequently, fetal protein accretion, an important component of fetal growth, also decreased (-62%; P < 0.001). We calculate that the reduction in fetal protein synthesis and breakdown, both processes that require intracellular expenditure of ATP, decreased fetal energy needs sufficiently to account for most, if not all, of the decrease measured in fetal oxygen consumption.

Animals↗

PubMed2006

Iron availability and consumption of tea, vervain and mint during weaning in Morocco.

BACKGROUND/AIMS: Iron deficiency impairs growth and psychomotor development of infants. In Morocco, infusions are introduced very early in infant diet, and could contribute to iron deficiency, due to their high polyphenol content. METHODS: The availability of tea, mint and vervain infusions was assessed using an in vitro model of digestion and dialysis. Two gastric pHs were used: pH 4 as in the first week life, and pH 2.5 as in older infants. Six repetitions of each experiment were made. The total polyphenol content of infusions was measured. RESULTS: At pH 4 and at pH 2.5, iron availability was decreased by tea and vervain, and increased by mint and ascorbic acid. At both pHs it was increased by addition of ascorbic acid to tea and vervain. In addition, at pH 2.5 it was increased by addition of ascorbic acid to mint. The highest value was observed in the presence of both ascorbic acid and mint (33.1 +/- 4.1%). In any case, iron availability was higher at pH 2.5 than at pH 4 (with single compounds or combinations with ascorbic acid). The polyphenol contents (mg/l) of tea, vervain and mint infusions were 2,236.1, 771.1, and 16.5. CONCLUSIONS: Tea and vervain infusions inhibited iron availability. In contrast, mint improved it; vitamin C helped in preventing these inhibiting properties. It could be proposed to discourage tea and vervain drinking at early weaning and to replace them by mint infusion, or at least to promote the consumption of vitamin C-rich fruit juice to counteract these inhibiting effects.

Ascorbic Acid↗

PubMed1996

Metabolic interfaces between growth and reproduction. V. Pulsatile luteinizing hormone secretion is dependent on glucose availability.

To test the hypothesis that mechanisms controlling the secretion of LH are modulated by glucose availability, the acute effects of glucoprivation were studied. The model was the gonadectomized male lamb raised on a limited diet of artificial milk. The approach was to monitor LH secretion before and after the administration of a competitive antagonist of glucose metabolism, 2-deoxyglucose (2DG). We first determined whether LH secretion was influenced by glucose availability by administering 2DG at several doses. Peripheral administration of the glucose antagonist (240 and 480 mg/kg 2DG, single iv injection) transiently decreased LH pulse frequency, but not LH pulse amplitude. By contrast, LH secretion (frequency or amplitude) was not affected by lower doses (60 or 120 mg/kg) of the glucose antagonist. A second study was conducted to determine whether either the pituitary gland or the GnRH neurosecretory system per se is directly affected by short term glucoprivation. The competency of the pituitary was assessed by administering GnRH during the time when LH secretion is suppressed by pharmacological glucose blockade. Similarly, the function of the GnRH neurosecretory system was assessed by administering a GnRH secretagogue (N-methyl-D,L-aspartate) under the same glucoprivic conditions. In response to an optimized iv dose of 2DG, LH pulse frequency decreased. However, in lambs that received either GnRH or N-methyl-D,L-aspartate during the period of glucoprivation, LH pulse frequency was sustained at levels comparable to those before 2DG was given. To determine whether the effect of glucoprivation was central in origin, the glucose antagonist was administered into the lateral cerebral ventricle at 1/100th the doses used peripherally. Central administration of 2DG, independent of dose, transiently decreased LH pulse frequency, but not pulse amplitude. However, unlike the case with peripheral injection, plasma glucose values did not change after the administration of any dose of 2DG tested centrally. These findings indicate that glucose availability in the developing sheep influences LH secretion. Moreover, based upon analysis of LH pulse frequency, glucoprivation does not directly impair either the pituitary gland or the GnRH neurosecretory system. Collectively, these results suggest that glucose availability affects LH secretion by acting within the central nervous system at a detection site(s) peripheral to the GnRH neuron.

Animals↗

PubMed1997

A comparison of pulmonary availability between Ventolin (albuterol) nebules and Ventolin (albuterol) Respirator Solution.

The two most common albuterol preparations used for nebulization are: (1) Ventolin (albuterol) respirator solution (Glaxo Canada Inc; Montreal, Canada) of which 2.5 mg (0.5 mL) is diluted with 2 mL of normal saline solution, and (2) the preservative-free, prediluted Ventolin (albuterol) Nebules PF (Glaxo) (2.5 mg/2.5 mL). The two preparations were compared using both a Hudson 1720 "T" up-draft Neb-U-Mist jet nebulizer and a Hudson 1730 "T" up-draft Neb-U-Mist II jet nebulizer (Hudson; Temecula, Calif), which were driven by a compressor (Pulmo-Aide; Devilbiss; Somerset, Pa) and by dry compressed air at 6 and 8 L/min. Particle size distribution was measured with a particle sizer (Malvern 2600; Malvern Instruments; Malvern, UK) and drug output for the nebulizer was calculated from the differences in predrug and postdrug volume and concentration. Drug availability was defined as the amount of drug carried in particles less than 5 microns in diameter. Drug availability was greater with the albuterol respiratory solution, due to the surface activity of the preservative benzalkonium chloride, for both nebulizers but particularly for the 1720. Differences in drug availability between nebulizers exceeded fourfold depending on the preparation, the nebulizer, and the nebulizing flow. These differences could not have been predicted from the manufacturer's specifications. The results suggest that prediction of drug availability must be based on measurements with the specific preparation and the specific nebulizer used.

Aerosols↗

PubMed2001

Binding of mineral elements to locust bean gum influences availability in vitro.

Experiments were conducted to evaluate the extent to which element binding of locust bean gum (LBG) affects the availability of calcium, iron, and zinc in the gut. Infant formula was supplemented with increasing amounts of LBG and subjected to an intraluminal digestion procedure. Element binding was measured by eliminating the complexes by twofold centrifugation. Availability of the elements was determined using a validated continuous-flow dialysis technique. Elemental content of the samples, supematants, and dialysates was analyzed with validated atomic absorption spectrometry. LBG provided small amounts of intrinsic calcium (1.13+/-0.02 mg/g) and trace amounts of iron (0.02+/-0.00 mg/g) and zinc (0.01+/-0.00 mg/g), which were strongly bound to the LBG molecule (respectively: 76.6+/-3.3%, 83.4+/-1.2%, 96.7+/-6.6%). Correlation analysis, between percent element bound by LBG after centrifugation and percent trapped after dialysis, yielded significant correlation only for the data of zinc (r = 0.93). For calcium and iron, no correlation could be demonstrated; however, for iron a similar trend was observed. These findings suggest that element binding of LBG has a major influence on the availability of zinc and maybe of iron. For calcium, other factors might also be involved, affecting availability.

Biological Availability↗

PubMed1984

The effect of nitrate on the oxygen availability during exercise in effort angina pectoris.

Respiratory responses during exercise were observed to determine whether improvement of oxygen availability in working skeletal muscle is attributable to increased aerobic capacity after administration of nitrate in patients with effort angina. After isosorbide dinitrate (ISDN) administration, the aerobic capacity increased 3.3 ml/min/Kg (20%) as compared with the control test (p less than 0.001), but the anaerobic threshold (AT), a good indicator of oxygen availability, was unchanged, and the respiratory quotient at the peak of exercise was elevated. These findings suggest that oxygen availability in skeletal muscle was not altered after ISDN, and increased exercise load accompanied increased anaerobic glycolysis. It was concluded that the nitrate-induced increase in aerobic capacity was not dependent upon the change in oxygen availability in skeletal muscle but rather upon the elevated anginal threshold.

Adult↗

PubMed2005

Autoclaving soil samples affects algal-available phosphorus.

Unwanted microbial interference in samples used for biological assays of P availability has routinely been eliminated by autoclaving samples before inoculation with algae. Twenty-three soils were selected to evaluate the relationship between algal growth in P-deficient solutions containing small quantities of soil and the level of P determined by a variety of tests used to evaluate P availability in soils and sediments. Soils were either autoclaved or not before addition to flasks containing P-starved algae in a nutrient solution without P. Compared to non-autoclaved samples, autoclaving soil resulted in approximately 60% more available P as estimated by increased algal growth. However, algal growth in the presence of autoclaved soil was highly correlated with growth in the presence of non-autoclaved samples. There was no consistent change in the correlations (r) between autoclaving or non-autoclaving samples in the relationships of algal numbers with P extracted by a number of soil tests. The effect of autoclaving soil on soluble P was also evaluated for a subset of six soils. Autoclaved soils had significantly greater concentrations of soluble P than non-autoclaved soils, with 78% more orthophosphate monoesters, 60% more orthophosphate diesters, and 54% more soluble inorganic P. Inhibition of algal growth may have occurred with two high-Zn soils that produced relatively low numbers of algae despite being very high in estimated available P by all extraction methods. Removing those samples from the calculations dramatically improved correlations between soil P measured by various methods and algal growth. With these two soils removed from calculations, algal growth with autoclaved soil was most highly correlated with Olsen P (r = 0.95), with other correlations as follows: Fe-oxide strip (r = 0.80), Mehlich 3 (r = 0.75,), modified Morgan (r = 0.61), and Bray-Kurtz 1 (r = 0.57).

Biological Availability↗

PubMed1983

Plasma alkaline phosphatase as a criterion for determining biological availability of phosphorus for swine.

One hundred thirty-nine pigs, with an average initial weight of 15.9 kg, were used in three trials to evaluate plasma alkaline phosphatase (AP) as a criterion for estimating available P in feedstuffs for swine. The first two trials were designed to determine the effect of adding graded levels of P (as KH2PO4) to a basal diet on the AP response pattern and degree of linear fit with time. Plasma AP increased (P less than .05) with time and, when regressed on the concentration of total P (.26 to .50%), provided the best linear fit by d 14 (r = -.996). This high degree of fit was maintained through d 21 (r = -.983). The poor correlation observed at 7 d (r = -.828) indicated that the AP pattern was not fully established, whereas departure from the close association by 28 d (r = -.913) may be related to a decline in the magnitude of P deficiency with increasing weight. In a third trial, available P was determined in high moisture corn (HMC, 24.6% moisture) using both AP and bone breaking strength (BKS) as response criteria. A standard curve was established by supplementing the basal diet (.26% P, .65% Ca) with graded levels of KH2PO4. High moisture corn was substituted for dextrose on an equal dry matter basis. Blood samples were acquired on d 14 and 21 for AP analysis and pigs were killed on d 28 for determination of metatarsal BKS. Phosphorus from HMC was determined (slope-ratio technique) to be 41.3% available using BKS as the criterion (KH2PO4, r = .961; HMC, r = .994) and 43.8% when AP at 14 d was used (KH2PO4, r = -.988; HMC, r = -.999). The data indicate that AP is a sensitive index potentially useful in P availability studies.

Alkaline Phosphatase↗

PubMed1984

Effects of source and particle size on the biological availability of calcium in calcium supplements for growing pigs.

Five experiments were conducted to determine the biological availability of the Ca in high-Ca (calcitic) limestone, dolomitic limestone, oyster shell flour, gypsum, marble dust and aragonite for the growing pig, and to determine the influence of particle size of the Ca source on the bioavailability of Ca. A low-Ca, fortified, corn soybean meal basal diet calculated to contain .2% Ca and .6% P was used. This diet was supplemented with 0 or .3% Ca from either CaCO3 precipitate (the standard) or the test source of Ca. Diets were fed on an ad libitum basis to three to eight replicate pens of pigs (one or two/pen) for 35 to 42 d. Average initial weight of the pigs was 15 kg. At the end of each experiment the pigs were killed, the third and fourth metacarpals and metatarsals and the femurs were removed, and breaking strength and ash were determined. The increase in bone strength from feeding the test source of Ca relative to the increase in bone strength from feeding the CaCO3 standard was used to calculate the relative availability of Ca in the supplements. The bioavailability of Ca in calcitic limestone (two sources), oyster shell flour, gypsum, marble dust and aragonite was similar, ranging from 93 to 102%. However, the Ca in two sources of dolomitic limestone was less available (51 and 78%) than in the other sources. Particle size of the Ca sources (geometric mean diameter of .10 to .54 mm) did not influence the availability of Ca.

Animals↗

PubMed1980

Apparent amino acid availability and apparent metabolizable energy values of tower and candle rapeseeds and rapeseed meals.

An experiment was conducted to measure the amino acid (AA) availability and metabolizable energy of whole and ground Tower and Candle rapeseeds (RS). This was done by the apparent metabolizable energy (AME) method of total excreta collection using mature White Leghorn cockerels. Since the AA availability values were not corrected for metabolic plus endogenous AA losses they were called apparent AA availability (AAAA) values. A sample of soybean meal (SBM) and Tower and Candle rapeseed meals (RSM) were also included in the experiment. The AAAA values for the whole and ground RS of any particular cultivar did not differ significantly. The values for Tower RS were higher than those for the Candle RS or the two RSM. However, compared with those of the RS and RSM, the SBM showed somewhat higher AAAA values. The AME values of whole Tower and Candle RS were much lower than the corresponding values obtained with ground seed. Furthermore, Candle RS, whole or ground, was lower in AME content than the corresponding values for Tower rapeseed. The Tower and Candle RSM were similar in their AME contents but lower than the SBM. The AAAA and AME results with RS showed that while grinding increased the AME values of the seeds, it did not enhance their AA availabilities.

Amino Acids↗

PubMed1984

Use of plasma and egg yolk biotin of white Leghorn hens to assess biotin availability from feedstuffs.

A linear relationship (r greater than .98) was found between the level of dietary biotin and plasma and egg-yolk biotin in White Leghorn hens after feeding the experimental diets for 2 weeks. This shows high reliability of these parameters as indicators of biotin availability. When plasma and egg yolk biotin were used to assess biotin availability in feedstuffs, they indicated low values for wheat (0%) and sorghum (10 to 20%) and high values for corn (75 to 100%), soybean meal (100%), and meat and bone meal (85%). When these parameters were used to assess commercial poultry diets, they indicated values for a "layer" diet of 75 to 100% and for a "broiler" diet of 81 to 92%. Pelleting gave an increase in biotin availability of 10% over the mash diet. This method for assessing biotin availability promises to be simple, economic, rapid, and reliable.

Animal Feed↗

PubMed1988

Bioavailability of amino acids in plant feedstuffs determined by in vitro digestion, chick growth assay, and true amino acid availability methods.

An in vitro, pepsin-pancreatin digestibility method was used to estimate the bioavailabilities of amino acids in plant feedstuffs, including two cultivars of four cereal grains and three high-protein feedstuffs. As a technique for separating hydrolytic products from substrate, trichloroacetic acid (TCA) was compared with three ultrafiltration techniques. Solutions were filtered continuously by a membrane of 500-Dalton pore size (cUF) and terminally by membranes of 500 Dalton (tUF) and 10,000 Dalton (CX). Additionally, bioavailability of amino acids was determined in vivo by the true amino acid availability (TAAA) method and utilization of lysine was determined by chick growth assay (CGA). Correlations of in vitro and in vivo estimates of availabilities were ranked CX = cUF greater than tUF greater than TCA for total amino acids and were ranked similarly for most individual amino acids. When determined using the superior technique, correlation between in vitro digestibilities of amino acids and TAAA were moderately high for the combined cereal grains (r = .92), were lower when data included wheat middlings (r = .90), but were unreliable when data included soybean meal and corn gluten meal (r = .29). Prediction of CGA values from in vitro digestibility was less reliable (r = .42) than that using TAAA values. There was agreement between values for lysine availability when determined for six grain samples by CGA and TAAA (r = .79). Evaluation from the correlations of the in vitro with the in vivo estimates of availabilities indicated that terminal filtration by a membrane of medium pore size (10,000 Dalton) or continuous filtration by a membrane of very low pore size (500 Dalton) made separations superior to those of terminal filtration (500 Dalton) and TCA precipitation.

Amino Acids↗

PubMed2001

Effect of drug solubility on in vitro availability rate from suppositories with polyethylene glycol excipients.

Factors involved in the availability mechanism of different drugs from suppositories with polyethylene glycol (PEG) excipients were studied using an in vitro model of the rectal compartment with a porous membrane simulating the rectal barrier. Different from lipophilic excipients, the drug is released as a consequence of the progressive dissolution of PEG into the intrarectal aqueous phase. Drug concentration in this small intrarectal phase produces the gradient against the large volume of the plasmatic phase, which regulates the diffusion rate through the barrier. As with lipophilic excipients, drug solubility in water was found to be an important factor influencing suppository release rate. Nevertheless, PEG influenced in vitro drug availability considerably, by increasing both drug solubility and dissolution rate. The osmotic effect of PEG in the intrarectal compartment influenced the increase in volume of the aqueous phase. The results, compared with those obtained from suppositories with a lipophilic excipient, show a higher dissolution rate from PEG excipient, but a higher diffusion rate across the barrier did not always correspond. Drugs less soluble in water showed a greater availability from PEG suppositories. On the contrary the more soluble drugs were less available.

Area Under Curve↗

PubMedDate not supplied

Comparison of estimates of first-year dairy manure nitrogen availability or recovery using nitrogen-15 and other techniques.

Measurements of dairy manure nutrient availability to crops typically show great variability. Approaches that are more accurate are needed to improve manure management and reduce nutrient loss to the environment. In this study, we compared direct (15N recovery) and indirect (difference method [Diff Meth] and fertilizer equivalence [FE] approach) methods of determining first-year dairy manure N availability or recovery during three cropping seasons. A field experiment was conducted on a Plano silt loam (fine-silty, mixed, superactive, mesic Typic Argiudolls) planted to corn (Zea mays L.). Plots received either manure, fertilizer N, or no N. Microplots receiving 15N-labeled manure were also established each study year. Manure was applied to a new plot each cropping season. Whole-plant N uptake was the best crop parameter to use for FE estimates. Estimates of N availability by relative effectiveness (Rel Eff), which are derived from the Diff Meth, and FE were similar (32 and 41%, respectively) and higher than unlabeled N or 15N recovery measurements because these indices factor in N use efficiency. Measures of the Rel Eff of manure N use were highly affected by control plot N uptake. The FE approach is less influenced by control plots, but it requires the inclusion of several more treatments and use of mathematical functions to describe crop response to N. These limitations are reflected in the wide ranges obtained for N availability estimates (-60 to 148%). Although apparent N recovery by the Diff Meth (14%) or direct measurements of 15N recovery (16%) were close on average, variability tended to be much lower for the 15N method. In addition, the Diff Meth was highly dependent on initial soil conditions. Use of 15N-labeled manure, although more costly and time-consuming, provided more consistent and reliable results.

Biological Availability↗

PubMed2005

In vitro availability of lomefloxacin hydrochloride in presence of essential and trace elements.

Lomefloxacin hydrochloride is a third generation fluoroquinolone antibacterial agent having a broad spectrum of action against a wide range of gram-positive and gram-negative organisms. The in vitro availability studies of lomefloxacin were carried out in presence of essential and trace elements such as magnesium, calcium, chromium, ferric, ferrous, cobalt, nickel, copper, zinc and cadmium in simulated gastric juice, simulated intestinal juice and blood pH at 37 degrees C using B.P 2003 dissolution test apparatus. It was observed that availability of lomefloxacin was depressed in presence of nickel and zinc in simulated gastric juice and in presence of Fe2+ in simulated intestinal juice, while many metals like magnesium, chromium, iron (both Fe2+ and Fe3+), cobalt, nickel, copper and cadmium depressed the availability of lomefloxacin at blood pH. Furthermore, the availability of lomefloxacin alone in simulated intestinal juice and at blood pH was reduced as compared to simulated gastric juice. The antibacterial activities of lomefloxacin in presence of these metal ions were observed and compared to control against six different microorganisms i.e., Staphylococcus aureus, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Bacillus fragilis and Streptococcus pneumonia by disc diffusion method to measure the inhibitory zone and MIC were determined by tube dilution method.

Anti-Bacterial Agents↗

PubMed1984

Influence of route of hepatic administration on drug availability.

The work investigates functional variability of hepatic arterial and portal venous streams in relation to drug availability. In an isolated rat liver system perfused in all experiments at a constant total flow of 10 ml X min-1, drug availability was found to be 18 and 3 times greater for lidocaine and meperidine, respectively, when infused through the hepatic artery compared to portal vein administration. When both hepatic artery and portal vein were perfused, drug availability increased log linearly for lidocaine, and linearly for meperidine with increasing hepatic artery flow contribution. Injection of 15-micron gamma-labeled microspheres into the hepatic artery and portal vein did not reveal arteriovenous or portovenous shunting channels greater than 15 micron in diameter. However, the ratios of the mean transit times of albumin and red blood cells were found to be significantly lower through the hepatic artery, indicating a possible reduction in perisinusoidal albumin space. When both hepatic artery and portal vein were perfused, linear correlations were obtained for values of this ratio plotted against increasing hepatic artery flow contributions. Data from the red blood cell transit time studies, as well as data on lidocaine availability, suggest the presence of functionally separate capillary beds for the hepatic arterial and venous streams.

Albumins↗