Comparison of non-invasive peripheral venous saturations with venous blood co-oximetry.

The estimation of venous oxygen saturations using photoplethysmography (PPG) may be useful as a noninvasive continuous method of detecting changes in regional oxygen supply and demand (e.g. in the splanchnic circulation). The aim of this research was to compare PPG-derived peripheral venous oxygen saturations directly with venous saturation measured from co-oximetry blood samples, to assess the feasibility of non-invasive local venous oxygen saturation. This paper comprises two similar studies: one in healthy spontaneously-breathing volunteers and one in mechanically ventilated anaesthetised patients. In both studies, PPG-derived estimates of peripheral venous oxygen saturations (SxvO2) were compared with co-oximetry samples (ScovO2) of venous blood from the dorsum of the hand. The results were analysed and correlation between the PPG-derived results and co-oximetry was tested for. In the volunteer subjects,moderate correlation (r = 0.81) was seen between SxvO2 values and co-oximetry derived venous saturations (ScovO2), with a mean (±SD) difference of +5.65 ± 14.3% observed between the two methods. In the anaesthetised patients SxvO2 values were only 3.81% lower than SpO2 and tended to underestimate venous saturation (mean difference = -2.67 ± 5.89%) while correlating weakly with ScovO2 (r = 0.10). The results suggest that significant refinement of the technique is needed to sufficiently improve accuracy to produce clinically meaningful measurement of peripheral venous oxygen saturation. In anaesthetised patients the use of the technique may be severely limited by cutaneous arteriovenous shunting.

The effect of vascular changes on the photoplethysmographic signal at different hand elevations.

In order to further understand the contribution of venous and arterial effects to the photoplethysmographic (PPG) signal, recordings were made from 20 healthy volunteer subjects during an exercise in which the right hand was raised and lowered with reference to heart level. Red (R) and infrared (IR) PPG signals were obtained from the right index finger using a custom-made PPG processing system. Laser Doppler flowmetry (LDF) signals were also recorded from an adjacent fingertip. The signals were compared with simultaneous PPG signals obtained from the left index finger. On lowering the hand to 50 cm below heart level, both ac and dc PPG amplitudes from the finger decreased (e.g. 18.70 and 63.15% decrease in infrared dc and ac signals respectively). The decrease in dc amplitude most likely corresponded to increased venous volume, while the decrease in ac PPG amplitude was due to regulatory adjustments on the arterial side in response to venous distension. Conversely, ac and dc PPG amplitudes increased on raising the arm above heart level. Morphological changes in the ac PPG signal are thought to be due to vascular resistance changes, predominately venous, as the hand position is changed.

Comparative carcass and tissue nutrient composition of transgenic Yorkshire pigs expressing phytase in the saliva and conventional Yorkshire pigs.

A transgenic line of Yorkshire (YK) pigs named the Cassie (CA) line was produced with a low copy number phytase transgene inserted in the genome. The transgenic line efficiently digests P, Ca, and other major minerals of plant dietary origin. The objectives of this study were to 1) compare carcass and tissue nutrient composition and meat quality traits for third generation hemizygous CA line market BW finisher pigs (n = 24) with age-matched conventional YK finisher pigs (n = 24) and 2) examine effects of outbreeding with high-index conventional YK boars on modifying carcass leanness from the third to sixth generations in CA line finisher boars (n = 73) and gilts (n = 103). Cassie boars (n = 12) and CA gilts (n = 12) were fed diets without supplemental P and comparable numbers of age-matched YK boars and gilts fed diets containing supplement P were raised throughout the finisher phase. The pigs were slaughtered and then fabricated into commercial pork primals before meat composition and quality evaluation. Proximate and major micronutrient composition was determined on tissues including fat, kidney, lean, liver, and skin. The main difference observed was greater (P = 0.033) crude fat content in CA boar carcasses and increased (P < 0.04) leaf lard in both CA boars and gilts but no differences were observed (P = 0.895 and P = 0.223, respectively) in carcass backfat thickness as compared with YK pigs. There were no substantive differences in tissue composition, except for CA boar kidneys. Numerous changes in the mineral, fatty acid, and indispensable AA composition for CA boar kidneys were not apparent in CA gilts. These changes may point to adaptive physiological changes in the boar kidney necessary for homeostatic regulation of mineral retention related to phytase action rather than to insertion of the transgene. However, from a meat composition perspective, transgenic expression of phytase in the CA line of YK pigs had little overall effect on meat composition. Outbreeding of high-index CA gilts with high-index commercial YK boars linearly reduced (P = 0.002) back fat thickness with a corresponding linear increase (P = 0.001) in lean yield in finisher CA gilts, although no change in these parameters was observed in CA finisher boars. The increase in lean yield in CA gilts by selective breeding without affecting the level of salivary phytase activity documents the value of conventional genetic selection in conjunction with genetic modification.

Phytase properties and locations in tissues of transgenic pigs secreting phytase in the saliva.

A transgenic Cassie (CA) line of Yorkshire (YK) pigs was developed using a transgene composed of the mouse parotid secretory protein promoter linked to the Escherichia coli phytase gene integrated in chromosome 4. Previous studies documented that salivary secretion of phytase was sufficient to enable efficient digestion of plant feed phytate P. In the present study the catalytic properties and tissue distribution of the phytase in CA pigs were determined by a combination of enzymatic assays, immunohistochemistry, and immunoblots of tissue samples. The E. coli phytase had a mass of 44.82 kDa whereas the phytase secreted in CA saliva had a mass of 52.42 kDa as a result of glycosylation of the enzyme in the parotid gland. Despite the difference in size, the 2 enzymes exhibited similar substrate specificities, and substrate affinity ( K: m) and maximum hydrolytic activity ( V: max) catalytic properties. Phytase assays showed that the enzyme was present at high specific activity in the salivary glands with low activity in the soft palate and essentially none in the kidney, lean (muscle), liver, or skin of CA pigs and none in YK pigs. This conclusion was supported by immunoblot analysis using a polyclonal anti-phytase antibody. Immunohistochemical analysis of 83 different tissue locations of CA and YK pigs confirmed the ubiquitous presence of phytase in serous cells of the salivary glands and the localized presence of phytase in both serous and mixed cell types in the submucosal glands of the oropharynx; in the pharynx, tonsils, and esophagus; in some Bowman's glands in the nasal mucosa and eustachian tube; and in the prostate gland of CA boars. Furthermore, it showed the absence of phytase from the kidney, lean, liver, and skin of CA pigs. Phytase was not detected in any of the conventional YK tissues tested. The phytase was found to be glycosylated with the allergenic galactose-α-1,3-galactose (α-gal) epitope by immunoblotting using α-gal specific monoclonal antibodies. Galactose-α-1,3-galactose glycosylation of proteins is a common feature of pork and other red meats. The α-gal epitope was shown to be associated with a few proteins in muscle and skin but with the greatest number of proteins in kidney and parotid tissues of CA and YK pigs. The absence of phytase from the major food tissues and the displacement of other α-gal glycosylated proteins in the parotid glands by α-gal glycosylated phytase in conjunction with previously published data support the contention that expression of the novel phytase has minimal influence on pork quality and safety.

Functional connectivity in the developing brain: a longitudinal study from 4 to 9months of age.

We characterize the development of intrinsic connectivity networks (ICNs) from 4 to 9months of age with resting state magnetic resonance imaging performed on sleeping infants without sedative medication. Data is analyzed with independent component analysis (ICA). Using both low (30 components) and high (100 components) ICA model order decompositions, we find that the functional network connectivity (FNC) map is largely similar at both 4 and 9months. However at 9months the connectivity strength decreases within local networks and increases between more distant networks. The connectivity within the default-mode network, which contains both local and more distant nodes, also increases in strength with age. The low frequency power spectrum increases with age only in the posterior cingulate cortex and posterior default mode network. These findings are consistent with a general developmental pattern of increasing longer distance functional connectivity over the first year of life and raise questions regarding the developmental importance of the posterior cingulate at this age.

Regional cerebral blood flow in children from 3 to 5 months of age.

BACKGROUND AND PURPOSE: Understanding the relationship between brain and behavior in early childhood requires a probe of functional brain development. We report the first large study of regional CBF by use of arterial spin-labeling in young children. MATERIALS AND METHODS: Cerebral blood flow by use of arterial spin-labeling was measured in 61 healthy children between the ages of 3 and 5 months. Blood flow maps were parcellated into 8 broadly defined anatomic regions of each cerebral hemisphere. RESULTS: There was no sex effect; however, group analysis demonstrated significantly greater CBF in the sensorimotor and occipital regions compared with dorsolateral prefrontal, subgenual, and orbitofrontal areas (P < .0001). A significant age effect was also identified, with the largest increase in blood flow between 3 and 5 months occurring in the following regions: orbitofrontal (P < .009), subgenual (P < .002), and inferior occipital lobe (P = .001). CONCLUSIONS: These results are consistent with prior histologic studies demonstrating regional variation in brain maturation and suggest that arterial spin-labeling is sensitive to regional as well as age-related differences in CBF in young children.

Pulse oximetry of body cavities and organs.

The focus of this paper will be in the development and in vivo applications of new custom made photoplethysmographic (PPG) and pulse oximetry optical and fiber optic sensors and instrumentation in an effort to investigate their suitability in the estimation of blood oxygen saturation and their contribution in the assessment of organ/tissue perfusion and viability. The paper describes the development of optical and fiber optic PPG and blood oxygen saturation (SpO2) sensors and covers examples of application areas including real-time PPG monitoring from body cavities (esophagus) and solid or hollow organs (bowel, liver, stomach, brain, etc). The clinical studies presented successfully demonstrated the feasibility in acquiring PPGs and estimating blood oxygen saturation values from a variety of organs and tissues. The technological developments and the measurements presented in this work pave the way in a new era of pulse oximetry where direct and continuous monitoring of blood oxygen saturation of internal organs and tissues could be made possible.

Digestive utilization of phosphorus from plant-based diets in the Cassie line of transgenic Yorkshire pigs that secrete phytase in the saliva.

A line of transgenic Yorkshire pigs referred to as the Cassie (CA) line was generated, which possessed a stable, low copy number phytase transgene insertion that enabled phytase secretion in the saliva. This study was conducted to assess growth and efficacy for improving P, Ca, and other macromineral utilization in the CA pigs receiving diets typical of those used for commercial swine production. In Exp. 1, 12 CA boars and 12 CA gilts fed diets without supplemental P gained weight and exhibited feed efficiency similar to conventional age-matched 12 Yorkshire boars and 12 Yorkshire gilts raised on similar diets with supplemental P. Serum concentrations of P and Ca were similar for CA and Yorkshire pigs during the growing and finishing phases, indicating that the CA pigs were not P limited. In Exp. 2, 6 CA (13.1 kg BW) and 6 Yorkshire barrows (8.8 kg BW) were fed 3 diets (control; low in Ca and P; and low in Ca, P, and CP) over 3 phases. The CA barrows fed the diet without supplemental P retained 25 to 40% (P < 0.001), 77 to 91% (P < 0.001), and 27 to 56% (P < 0.001) more P during the weaning, growing, and finishing phases, respectively, than conventional Yorkshire barrows fed similar diets without supplemental P. In Exp. 3, CA and Yorkshire barrows of similar ages weighing 66.2 ± 1.7 kg (n = 10) and 50.0 ± 1.0 kg (n = 10), respectively, were used. The P retention of CA finisher barrows fed a diet without supplemental P was 34% greater (P < 0.001) than conventional Yorkshire barrows fed the same diet with 750 units of exogenous phytase/kg diet. Urinary Ca to P ratio in the CA pigs was 0.27, whereas that for the Yorkshire barrows was 30, thereby, indicating that the Yorkshire barrows suffered a P deficiency. Furthermore, digestive utilization of major electrolyte macrominerals, K and Na, was improved (P < 0.05) by 18 and 16%, respectively, in the CA finisher pigs compared with the conventional Yorkshire finisher pigs fed phytase; however, only K exhibited enhanced retention. In conclusion, the CA line pigs secrete sufficient phytase from the salivary glands to enable efficient digestion of plant P, Ca, and major electrolyte macrominerals.

A practical approach to incidental findings in neuroimaging research.

OBJECTIVE: We describe the systematic approach to incidental findings (IFs) used at the Mind Research Network (MRN) where all MRI scans receive neuroradiologist interpretation and participants are provided results. METHODS: From 2004 to 2011, 8,545 MRI scans were acquired by 45 researchers. As mandated by MRN's external institutional review board, all structural sequences were evaluated by a clinical neuroradiologist who generated a report that included recommendations for referral if indicated. Investigators received a copy of their participants' reports, which were also mailed to participants unless they specifically declined. To better understand the impact of the radiology review process, a financial analysis was completed in addition to a follow-up phone survey to characterize participant perceptions regarding receiving their MRI scan results. RESULTS: The radiologist identified IFs in 34% of the 4,447 participants. Of those with IFs (n = 1,518), the radiologist recommended urgent or immediate referral for 2.5% and routine referral for 17%. For 80.5%, no referral was recommended. Estimated annual cost for this approach including support for the neuroradiologist, medical director, and ancillary staff is approximately $60,000 or $24/scan. The results of the retrospective phone survey showed that 92% of participants appreciated receiving their MRI report, and the majority stated it increased their likelihood of volunteering for future studies. CONCLUSIONS: Addressing IFs in a cost-effective and consistent manner is possible by adopting a policy that provides neuroradiology interpretation and offers participant assistance with clinical follow-up when necessary. Our experience suggests that an ethical, institution-wide approach to IFs can be implemented with minimal investigator burden.

A comparison of the respiratory effects of oxycodone versus morphine: a randomised, double-blind, placebo-controlled investigation.

Oxycodone's respiratory profile (particularly the extent of respiratory depression in comparison to morphine) remains to be fully characterised in the peri-operative period. We randomly assigned ASA 1-2 adults for elective surgery under general anaesthesia to receive saline, morphine 0.1 mg.kg⁻¹, or oxycodone 0.05 mg.kg⁻¹, 0.1 mg.kg⁻¹, or 0.2 mg.kg(-1) . Results were obtained from six patients in the saline group, 12 patients in the groups receiving morphine 0.1 mg.kg⁻¹, oxycodone 0.05 mg.kg⁻¹ and 0.1 mg.kg⁻¹, and from 10 patients who received oxycodone 0.2 mg.kg⁻¹. Patients were breathing spontaneously and minute ventilation monitored with a wet wedge spirometer for 30 min. All active groups demonstrated significant respiratory depression compared to saline (p < 0.0001 for all groups). The mean (SD) reduction in minute volume from baseline was 22.6% (10.4%) for the morphine 0.1 group and 53.3% (27.2%), 74.4% (12.9%) and 88.6% (13.5%) for the oxycodone 0.05, 0.1 and 0.2 groups, respectively, with significant dose dependent differences between oxycodone groups (p = 0.0007). The extent and speed of onset of oxycodone induced respiratory depression was dose dependent and greater than an equivalent dose of morphine.

Cerebral arterial oxygen saturation measurements using a fiber-optic pulse oximeter.

BACKGROUND: A pilot investigation was undertaken to assess the performance of a novel fiber-optic cerebral pulse oximetry system. A fiber-optic probe designed to pass through the lumen of a cranial bolt of the type used to make intracranial pressure measurements was used to obtain optical reflectance signals directly from brain tissue. METHODS: Short-duration measurements were made in six patients undergoing neurosurgery. These were followed by a longer duration measurement in a patient recovering from an intracerebral hematoma. Estimations of cerebral arterial oxygen saturation derived from a frequency domain-based algorithm are compared with simultaneous pulse oximetry (SpO2) and hemoximeter (SaO2) blood samples. RESULTS: The short-duration measurements showed that reliable photoplethysmographic signals could be obtained from the brain tissue. In the long-duration study, the mean (±SD) difference between cerebral oxygen saturation (ScaO2) and finger SpO2 (in saturation units) was -7.47(±3.4)%. The mean (±SD) difference between ScaO2 and blood SaO2 was -7.37(±2.8)%. CONCLUSIONS: This pilot study demonstrated that arterial oxygen saturation may be estimated from brain tissue via a fiber-optic pulse oximeter used in conjunction with a cranial bolt. Further studies are needed to confirm the clinical utility of the technique.

A prospective diffusion tensor imaging study in mild traumatic brain injury.

OBJECTIVES: Only a handful of studies have investigated the nature, functional significance, and course of white matter abnormalities associated with mild traumatic brain injury (mTBI) during the semi-acute stage of injury. The present study used diffusion tensor imaging (DTI) to investigate white matter integrity and compared the accuracy of traditional anatomic scans, neuropsychological testing, and DTI for objectively classifying mTBI patients from controls. METHODS: Twenty-two patients with semi-acute mTBI (mean = 12 days postinjury), 21 matched healthy controls, and a larger sample (n = 32) of healthy controls were studied with an extensive imaging and clinical battery. A subset of participants was examined longitudinally 3-5 months after their initial visit. RESULTS: mTBI patients did not differ from controls on clinical imaging scans or neuropsychological performance, although effect sizes were consistent with literature values. In contrast, mTBI patients demonstrated significantly greater fractional anisotropy as a result of reduced radial diffusivity in the corpus callosum and several left hemisphere tracts. DTI measures were more accurate than traditional clinical measures in classifying patients from controls. Longitudinal data provided preliminary evidence of partial normalization of DTI values in several white matter tracts. CONCLUSIONS: Current findings of white matter abnormalities suggest that cytotoxic edema may be present during the semi-acute phase of mild traumatic brain injury (mTBI). Initial mechanical damage to axons disrupts ionic homeostasis and the ratio of intracellular and extracellular water, primarily affecting diffusion perpendicular to axons. Diffusion tensor imaging measurement may have utility for objectively classifying mTBI, and may serve as a potential biomarker of recovery.

Preliminary evaluation of a new fibre-optic cerebral oximetry system.

A new system for measuring the oxygen saturation of blood within tissue has been developed, for a variety of patient monitoring applications. A particular unmet need is in the central nervous system, and this project aims to devise a means for measuring blood oxygen saturation in the brain tissue of patients recovering from neurosurgery or head injury. Coupling light sources and a photodetector to optical fibres results in a probe small enough to pass through a cranial bolt of the type already in use for intra-cranial pressure monitoring. The development and evaluation of a two-wavelength fibre-optic reflectance photoplethysmography (PPG) system are described. It was found that good quality red and near-infrared PPG signals could be obtained from the finger using a fibre-optic probe. Experiments were conducted to find the inter-fibre spacings that yield signals most suitable for calculating oxygen saturation. Reliable signals could be obtained for inter-fibre spacings between 2 mm and 5 mm, the latter being the size of the maximum aperture in the cranial bolt. A preliminary measurement from human brain tissue is also presented.

The evolution of trauma services at Beaumont Hospital.

OBJECTIVE: To review and examine the epidemiology, severity and management of trauma admissions at the national neurosurgical teaching hospital. METHODS: An extensive audit of volume, type and severity of injury and the management requirements of the trauma population admitted to the hospital. RESULTS: The vast majority of severely injured patients were referred from outside the catchment area of the hospital with only 26% being admitted directly through the Emergency Department. As a consequence, 73% of patients arrived out of normal working hours, which posed problems in providing skilled trauma specialists. CONCLUSIONS: The management of patients with serious injury is complex. The large proportion of patients with critical injuries, some of whom were paediatric, highlighted the need for 24 h cover by senior trauma personnel and the provision of radiology and operating facilities to meet their needs. The inclusion of indicators of alterations in innate or adaptive immune responses may improve the predictive power of severity of injury scores.

Hippocampal microdialysis during spontaneous intraoperative epileptiform activity.

BACKGROUND: The actual mechanisms underlying human hippocampal epileptogenicity, a process ultimately mediated by neurochemical events, remains to be fully elucidated. We submit early insight data regarding microdialysis (MD) recovery of the neuroactive amino acids glutamate, aspartate and gamma-aminobutyric acid (GABA) from the intraoperative and intact, spontaneously epileptiform human hippocampus. METHOD: Generally anaesthetised temporal lobe epilepsy (TLE) patients (N=7) undergoing therapeutic and anatomically standardised resective surgery were also subjected to ipsilateral anterior hippocampal MD with concomitant hippocampal electrocorticography (ECoG). Recovered 10-min dialysate samples were quantified for glutamate, aspartate and GABA using high-performance liquid chromatography; corresponding ECoG data was assessed for epileptiform activity (EA); mesial resection tissue was postoperatively examined and graded for hippocampal sclerosis. FINDINGS: Mean 'Sample 3' dialysate absolute recovery of glutamate, aspartate and GABA from hippocampi with minimal EA (N=5) was ( micro M+/-SEM): 6.406+/-2.143, 0.600+/-0.215, and 0.357+/-0.093, respectively. In contrast, 'Sample 3' dialysate absolute glutamate, aspartate and GABA levels ( micro M) from the hippocampi of two patients with vigorous EA were: 101.099 and 211.861, 21.860 and 14.482, and 4.241 and 4.817, respectively. Mesial resection tissue in all cases demonstrated hippocampal sclerosis, though the histopathological degree of sclerosis varied between patients. INTERPRETATION: These preliminary intraoperative findings suggest that dialysate glutamate, aspartate, and GABA levels from the sclerotic anterior hippocampus likely reflects the functional status of the sampled tissue - i.e., lower levels of these neuroactive amino acids are to be expected during quiescent or minimal EA versus considerably higher levels corresponding to vigorous EA.

Increased spontaneous DNA damage in Cu/Zn superoxide dismutase (SOD1) deficient Drosophila.

The superoxide dismutases (SODs) protect oxygen-using cells against reactive oxygen species, the potentially toxic by-products of respiration, oxidative metabolism, and radiation. We have previously shown that genetic disruption of CuZn SOD (SOD1) in Drosophila imparts a recessive phenotype of reduced lifespan, infertility, and hypersensitivity to oxidative stress. We now show that the absence of SOD1 increases spontaneous genomic damage. The increase in spontaneous mutation rate occurs in SOD1-null mutants in somatic cells as well as in the germ line. Further, we show that specific DNA repair-defective mutations, which are easily tolerated in SOD1(+) flies, lead to high mortality when introduced into the SOD1-null homozygous mutant background.

Diffuse primary non-Hodgkin's lymphoma of the cranial vault.

Primary non-Hodgkin's lymphoma of the skull vault is a rare disease. We describe a case occurring in a 72-year-old woman presenting with generalized tonic clonic seizures on a background of a 1-year history of headaches and progressively enlarging scalp masses. Imaging showed diffuse infiltration of the skull vault with multifocal intra- and extracranial soft tissue masses, causing compression and probably infiltration of the cerebral cortex. Further investigation failed to identify any other evidence of systemic lymphoma. Biopsy of one of the scalp masses showed a small to intermediate cell B cell lymphoma. The other nine reported cases of primary skull vault lymphoma are reviewed. The diffuse vault infiltration as well as the multiple intracranial, scalp and temporalis muscle masses renders this case unique.

The anatomical distribution of cerebral gliomas in mobile phone users.

We analysed the association between mobile phone use and the anatomical distribution of glial brain tumours in Irish neurosurgical patients. All patients with unilateral histologically proven glioma were enrolled over a 12 month period. We hypothesised that were a cellular phone to cause a glioma then it would do so on the dominant hand side. Fifty mobile phone users and twenty three non-users were identified. The vast majority of patients (69/73) were right handed and the right side of the brain was more common as the tumour site (48/73). Fisher's exact test revealed no statistical significance for glioma location based on the handedness of the patient in the mobile phone user group and location of the tumour in both user and non-user groups. We discuss our findings and the stable trend in the incidence of reported glioma cases.

Determination of true digestive utilization of phosphorus and the endogenous phosphorus outputs associated with soybean meal for growing pigs.

The objectives of this study were to determine true P digestibility, the gastrointestinal endogenous P outputs associated with soybean meal (SBM), and the role of the large intestine in P digestion in growing pigs. Four Yorkshire barrows, with average initial and final BW of 40 and 58 kg, were fitted with a simple T-cannula at the distal ileum and fed four diets according to a 4 x 4 Latin square design. The diets were cornstarch-based and contained four levels of P (0.098, 0.196, 0.293, and 0.391% on a DM basis) from solvent-extracted conventional SBM. Chromic oxide (3.5 g/kg of diet, as-fed basis) was included as a digestibility marker. Each experimental period consisted of 8 d with a 4-d adaptation period and a 4-d collection of representative ileal digesta (2 d) and fecal (2 d) samples. True ileal and fecal P digestibility values and the ileal and fecal endogenous P outputs associated with SBM were determined by the regression analysis technique. There were no differences (P > 0.05) in true P digestibility values (ileal, 59.0 +/- 8.3 vs. fecal, 51.3 +/- 7.9%, n = 16) and endogenous P outputs (ileal, 0.59 +/- 0.18 vs. fecal, 0.45 +/- 0.21 g/kg of DMI, n = 16) between the ileal and the fecal levels. The endogenous fecal P loss accounted for 8.1 and 17.6% of the NRC (1998) recommended total and available P requirements in growing pigs, respectively. In conclusion, approximately 51% of the total P in conventional SBM is digested in growing pigs. The large intestine does not play an important role in the digestion of P associated with SBM in the growing pig. The fecal loss of the gastrointestinal endogenous P is an important route of P excretion in the growing pig.