REASONS FOR PERFORMING STUDY:Previous studies have shown that in man ultrasonography is more accurate than radiography for detecting rib fractures.OBJECTIVES:To describe clinical, radiographic and ultrasonographic findings related with rib fractures in newborn foals in an equine critical care unit; and to compare diagnostic accuracy of ultrasonography to radiography.METHODS:A prospective ultrasonographic study was performed on 29 foals presented to the emergency unit. This study was performed at the Centre Hospitalier Universitaire Vétérinaire (CHUV), University of Montreal. Physical examination as well as radiographic and ultrasonographic examinations were performed.RESULTS:Thoracic radiographs revealed 10 rib fractures in 5 of 26 (19%) foals. Ultrasonography revealed 49 fractures in 19 of 29 (65%) foals of which fillies (n = 13; 68%) were significantly over represented as were fractures to the left thorax (n = 15; 78%). Seventeen of 19 foals (90%) had rib fractures located 3 cm or less from the costochondral junction, the distal part of the rib being displaced laterally in all cases. In 2 foals, where both thoracic radiographs and ultrasonography detected rib fractures, the site of fractures was located on the mid portion of the rib. Rib fractures were detected only by thoracic radiographs in one foal. Sixty-five percent (32/49) of fractured ribs had a moderate displacement (1-4 mm).CONCLUSIONS:Rib fractures are seen frequently in newborn foals in equine critical care units. Ultrasonography is more accurate than radiography and reveals fractures in most patients presented in emergency. The position (costochondral junction) of rib fractures and of the fragments suggest that most thoracic trauma probably occurs during parturition.POTENTIAL RELEVANCE:Ultrasound imaging increases awareness and improves the diagnosis of rib fractures in newborn foals.

Canine elbow incongruence is believed to be the consequence of underdevelopment of the radius. The purpose of this study is to determine the sensitivity and specificity of radiography to detect elbow incongruence in an in vitro model and to assess the optimal elbow angle and radiographic beam position. Five normal cadaveric canine left forelimbs were used. A four-pin, type 1 external fixator with a linear motor side bar was fixed to the cranial part of the radius of each limb and a 1 cm segment of bone was removed from the mid-diaphysis to allow radial shortening. Each elbow was subjected to the same protocol. They were radiographed at two different angles (90 degrees and 135 degrees) of flexion, with 10 different radiographic beam positions (centered on the humeral condyle, 3 cm cranial, 3 cm caudal, 3 cm distal, 3 cm proximal, 3 cm cranio-proximal, 3 cm cranio-distal, 3 cm caudo-proximal, 3 cm caudo-distal and on the shoulder joint) and at four different level of radial shortening (0, 1, 2 and 3 mm). In addition, a radiographic view centered on the elbows flexed at 135 degrees was made after simulating weight bearing. The acquired digital images were independently evaluated by three evaluators unaware of the elbows status. The elbows were judged normal, incongruent or borderline based on specific criteria. The sensitivity for detection of elbow incongruence at and beyond 2 mm was excellent at 90 degrees (median = 100% for all views) and good at 135 degrees (median = 80%) of flexion with no difference between examiners. The sensitivity at 1 mm of incongruence was unchanged at 135 degrees but was reduced at 90 degrees of flexion (median = 60%) with a significant difference between the evaluators. The specificity was significantly different between the evaluators and ranged from 70% to 90% at 90 degrees of flexion and from 50% to 80% at 135 degrees. The lowest specificities at 90 degrees were obtained with the proximal displacements of the X-ray beam. Simulating weight bearing significantly decreased the sensitivity at 1 mm (from 80% to 50%) and 3 mm (from 100% to 80%) of incongruence and slightly increased the specificity (from 55% to 65%). Radiography is a sensitive and specific test to detect moderate-to-severe radio-ulnar incongruence (2 mm and over) if the elbow is flexed at a 90 degrees angle regardless of the radiographic beam position. Finally, canine elbow incongruence appeared reduced after an in vitro weight-bearing simulation.

OBJECTIVE:To compare the biomechanical effects of multistage versus one-stage destabilization of a type II external skeletal fixator (ESF) used to stabilize an oblique unstable tibial osteotomy in dogs.STUDY DESIGN:In vitro, in vivo, and ex vivo experimental study.ANIMAL POPULATION:Twelve healthy adult dogs.METHODS:The biomechanical characteristics of the type II ESF used in this study were determined. This fixator was applied to both tibiae of two groups of 6 dogs to stabilize a 2-mm-wide oblique osteotomy. One fixator on each dog remained unchanged throughout the 11-week study (control group). The fixator on the opposite limb was destabilized late and acutely in one group of dogs (single-stage) and early and progressively in the other (multistage). Clinical examination, radiographic examination, and force-plate analysis were used to evaluate the results. All dogs were euthanatized at 11 weeks. All tibiae were scanned to determine the cross-sectional area of the callus in the center of the osteotomy and subjected to biomechanical tests to determine mean pull-out strength of pins and callus strength and stiffness.RESULTS:Stiffness of the type II ESF used in this study was 578 N/mm in axial compression, 0.767 Nm/deg in torsion, 261 N/mm in medio-lateral bending, and 25 N/mm in cranio-caudal bending. Peak vertical forces of the hindlimbs were significantly lower at 2.5 and 5 weeks than before surgery. Peak vertical forces of the hindlimbs did not change before and after destabilization. No significant differences could be detected between the two destabilization sequences or between all control tibiae and pooled destabilized tibiae with regards to radiographic evaluation of the healing osteotomy, cross-sectional periosteal callus area, mean pull-out strength of transfixation pins, callus strength, and callus stiffness.CONCLUSIONS AND CLINICAL RELEVANCE:Bone healing of unstable osteotomies stabilized with a type II ESF is not significantly enhanced by staged destabilization of the fixation as performed in this study.

The objectives of this study were to standardize a palpation technique and to determine within and between examiners, the repeatability in interpreting the angle of reduction, subluxation and the acetabular slope measurements. Also it was desired to ascertain the effect of pelvis positioning on the acetabular slope measurement on six-month-old dogs. On palpation examination fifty-three (53) dogs had their angles of reduction and subluxation measured. A radiographic examination including, a standard hip-extended view, a compression and a distraction view and a dorsal acetabular rim view were performed on each dog. The within examiner repeatability was excellent for both the angle of reduction and subluxation (r = 0.975, p = 0.82 and r = 0.977, p = 0.81 respectively). The between examiners repeatability was good for the angle of reduction (r = 0.843, p = 0.51) but only a fair correlation was found for the angle of subluxation (r = 0.652, p = 0.83). For the acetabular slope measurement, an excellent within examiner correlation was observed (r = 0.940, p = 0.52). However, though a good correlation was found between examiners, a significant difference was found in the measurements of the three examiners (r = 0.780, p < 0.0001). The under- or overrotation position slightly changed the slope measurement but a fair correlation was still observed with the perfect position (r = 0.769, p = 0.074 and r = 0.684, p = 0.061 respectively). If the pelvis is turned to one side, a correlation was not found (r = 0.090, p = 0.847). The high repeatability of the angle of reduction measurement in six-month-old dogs suggests that it may be used by multiple examiners, with the expectation of comparable and consistent results. The modified method of the acetabular slope measurement improved the correlation, but a significant difference was still observed between examiners.

SummaryThe objectives of this study were to standardize a palpation technique and to determine within and between examiners, the repeatability in interpreting the angle of reduction, subluxation and the acetabular slope measurements. Also it was desired to ascertain the effect of pelvis positioning on the acetabular slope measurement on sixmonth- old dogs. On palpation examination fifty-three (53) dogs had their angles of reduction and subluxation measured. A radiographic examination including a standard hip-extended view, a compression and a distraction view and a dorsal acetabular rim view were performed on each dog.The within examiner repeatability was excellent for both the angle of reduction and subluxation (r = 0.975, p = 0.82 and r = 0.977, p = 0.81 respectively). The between examiners repeatability was good for the angle of reduction (r = 0.843, p = 0.51) but only a fair correlation was found for the angle of subluxation (r = 0.652, p = 0.83). For the acetabular slope measurement, an excellent within examiner correlation was observed (r = 0.940, p = 0.52). However, though a good correlation was found between examiners, a significant difference was found in the measurements of the three examiners (r = 0.780, p < 0.0001). The under- or overrotation position slightly changed the slope measurement but a fair correlation was still observed with the perfect position (r = 0.769, p = 0.074 and r = 0.684, p = 0.061 respectively). If the pelvis is turned to one side, a correlation was not found (r = 0.090, p = 0.847). The high repeatability of the angle of reduction measurement in six-month-old dogs suggests that it may be used by multiple examiners, with the expectation of comparable and consistent results. The modified method of the acetabular slope measurement improved the correlation, but a significant difference was still observed between examiners.Early detection in life of canine hip dysplasia is important. The angle of reduction and the acetabular slope have been evaluated as diagnostic tools. With regard to its repeatability between examiners, the use of the angle of reduction by multiple examiners will be acceptable. The correlation between examiners in the acetabular slope measurement was good but a significant difference was present. Part two is now being analyzed.

OBJECTIVE To describe a surgical technique involving distraction and stabilization of the lumbo-sacral vertebral segment using an external skeletal fixator in dogs with lumbosacral instability caused by discospondylitis. STUDY DESIGN Retrospective clinical study. ANIMALS Four client-owned dogs. METHODS Medical records of all dogs diagnosed with discospondylitis from 1994 to 1997 were identified and reviewed. Four dogs with lumbosacral discospondylitis requiring surgical treatment were then specifically studied. Surgical technique, clinical signs, preoperative diagnostic investigation, radiographic findings, and the results of short-term and long-term reevaluations were recorded. RESULTS Twelve dogs with discospondylitis were identified, 4 of which had lumbosacral discospondylitis. These 4 dogs underwent surgical distraction and stabilization because they failed to respond to medical treatment. Three dogs received a cancellous bone graft between L7 and S1 and had rapid interbody fusion of this vertebral segment. The dog that did not receive a graft did not have interbody fusion at the time of fixator removal. This did not affect the final clinical outcome. Lumbosacral pain and neurological deficits present before surgery rapidly subsided after the procedure. All dogs received concurrent antibiotic treatment for a minimum of 4 weeks. All dogs were clinically normal at the time of fixator removal and all continued to do well during the follow-up period (8-48 months; mean, 27.5 months). CONCLUSION AND CLINICAL RELEVANCE Lumbosacral discospondylitis may not respond well to conservative treatment because of the mobility of the affected space. Surgical treatment involving distraction and stabilization to obtain intervertebral fusion is very effective in treating lumbosacral instability caused by discospondylitis.

SummaryThe efficiency of conservative treatment, excision arthroplasty of the femoral head and neck and triple pelvic osteotomy for the treatment of hip dysplasia in the immature dog were compared using locomotor, physical and radiographic examinations and owner’s evaluation. Cases selected for this study were dogs diagnosed with bilateral hip dysplasia, initially admitted with clinical signs (lameness, pain), immature at the beginning of the treatment (less than 12 months of age), with both hips subjected to the same treatment (conservative treatment, excision arthroplasty of the femoral head and neck or triple pelvic osteotomy). These dogs never showed any musculoskeletal problems other than hip dysplasia and the surgical treatment had been completed at least 20 months prior to re-evaluation time. Fourteen hips were re-evaluated in the conservative group, 16 in the triple pelvic osteotomy group and ten in the excision arthroplasty group. Locomotor, physical and owner’s evaluations demonstrated the superiority of the triple pelvic osteotomy. These evaluations also showed that excision arthroplasty was more efficient than conservative treatment. Radiographic examination demonstrated the obvious superiority of the triple pelvic osteotomy over conservative treatment.Locomotor, physical and owner’s evaluations demonstrated the superiority of the triple pelvic osteotomy over conservative treatment and excision arthroplasty for the treatment of hip dysplasia in the immature dog. Radiographic examination demonstrated the obvious superiority of the triple pelvic osteotomy over conservative treatment for joint congruence and control of degenerative joint disease.

OBJECTIVE:To compare analgesic effects of ketoprofen, oxymorphone hydrochloride, and butorphanol when used to control postoperative pain associated with elective orthopedic surgery in dogs. DESIGN:Prospective randomized clinical trial. ANIMALS:70 dogs undergoing orthopedic surgery on a hind limb. PROCEDURE:Dogs were randomly assigned to 1 of 4 postoperative analgesic treatment groups: ketoprofen alone, oxymorphone alone, butorphanol alone, or ketoprofen-oxymorphone. Drugs were given IM at the end of anesthesia. Pain score, sedation score, arterial blood pressures, arterial blood gas partial pressures, and plasma cortisol concentration were measured for 12 hours after surgery. If the pain score was > or = 9, supplemental oxymorphone was administered IM. RESULTS:The proportion of dogs that did not require supplemental treatment with oxymorphone was significantly higher for the ketoprofen alone and ketoprofen-oxymorphone groups than for the oxymorphone alone group. During the first hour after surgery, pain score was lower for oxymorphone alone and ketoprofen-oxymorphone groups than for ketoprofen or butorphanol alone groups. Significant differences were not detected among groups in regard to pain score 2 and 3 hours after surgery or in regard to arterial blood pressures at any time. From 4 to 12 hours after surgery, pain score was significantly lower for the ketoprofen alone group than for other groups. Plasma cortisol concentration was significantly higher for the oxymorphone alone group 6 and 8 hours after surgery, compared with other groups. CLINICAL IMPLICATIONS:Except during the first hour after surgery, dogs given ketoprofen alone after elective orthopedic surgery had a greater level of, and longer-lasting, analgesia than did dogs given oxymorphone or butorphanol alone.

Whereas the direct action of sex steroids, namely of androgens, on prostate cell division was questioned as early as in the 1970s, and remains so, the interest in prostatic growth factors (GFs) is rather recent but has expanded tremendously in the last five years. This lag period can be partly explained by the fact that, at the time, androgen receptors had just been discovered, and newly developed hormonal regimens or strategies to treat patients with prostate carcinoma (PCa) or epithelioma had generated great enthusiasm and hopes in the medical and scientific community. Another point to consider was the difficulty in maintaining prostate tissues in organ cultures and the relative novelty of culturing prostate epithelial cells in monolayers. Failures of sex steroids to elicit a direct positive response on prostate cell divisionin vitro, as seenin vivo, were interpreted as resulting from inappropriate models or culture conditions. However, the increasing number of reports confirming the lack of mitogenic activity of sex steroidsin vitro, coupled with the powerful mitogenic activity of GFs displayed in other systems, the discovery of GF receptors (GF-Rs), and the elucidation of their signalling pathways showing sex steroid receptors as potential substrates of GF-activated protein kinases gradually led to an increased interest in the putative role of GFs in prostate physiopathology. Of utmost importance was the recognition that hormone refractiveness was responsible for PCa progression, and for the poor outcome of patients with advanced disease under endocrine therapies. This problem remains a major issue and it raises several key questions that need to be solved at the fundamental and clinical levels.

Because protein tyrosine kinases play a crucial role in the regulation of cell division and carcinogenesis, we have herein measured such enzyme activities (specific activity and subcellular distribution) and compared their characteristics with respect to hydrodynamic properties and radiation inactivation sizes as well as renaturation after electrophoresis in denaturing conditions in canine prostatic epithelial cells either in a resting (freshly isolated) or in a dividing (cultured cells) state. In quiescent cells, most protein tyrosine kinase activity was expressed by soluble proteins with a Stokes' radius (Rs) of 3.05 nm, a sedimentation coefficient (S20,w) of 4.0 S, and a molecular mass of 50 kDa. By contrast, in dividing cells (three days in primary culture), the specific activity was higher and the enzyme was mainly membrane bound. The use of a detergent (Triton X-100) allowed the extraction of most of that enzyme; its partial specific volume, S20,w and Rs were then 0.883 cm3/g, 4.0 S, and 5.6 nm, respectively, hence yielding a molecular mass of 215 kDa, which decreased to 125-145 kDa when corrected for detergent binding. Probing these chromatography-peak fractions, 50 kDa from cytosol of resting cells and 215 kDa from membrane extracts of dividing cells, with a phosphotyrosine antibody following their incubation with ATP and electrophoresis in denaturing conditions revealed the presence of a common 50-kDa phosphotyrosylated protein along with three other bands (130, 75, and 40 kDa) in the high-Mr peak of enzyme. However, the radiation inactivation size for protein tyrosine kinases expressed in both resting and dividing cells were similar, 47.2 +/- 8.7 and 44.5 +/- 6.1 kDa, respectively. Furthermore, by renaturation after electrophoresis in denaturing conditions, major protein tyrosine kinase polypeptides of 50 kDa were identified in both cell populations. Taken together, these results indicate that, in dividing prostatic epithelial cells, membrane-bound protein tyrosine kinases of low molecular weight with properties similar to those of monomeric soluble forms present in quiescent cells are part of high-molecular weight complexes. This activation process may be critical for hormone-independent proliferation of prostatic epithelial cells.

The radiation inactivation method is widely used to estimate the molecular size of membrane-bound enzymes, receptors, and transport systems in situ. The method is based on the principle that exposure of frozen solutions or lyophilized protein preparations to increasing doses of ionizing radiations results in a first-order decay of biological activity proportional to radiation inactivation size of the protein. This parameter is believed to reflect the "functional unit" of the protein defined as the minimal assembly of structure (protomers) required for expression of a given biological activity. We tested the functional unit as a concept to interpret radiation inactivation data of proteins with Escherichia coli beta-galactosidase, where the protomers are active only when associated in a tetramer. Gamma-Irradiation of beta-galactosidase at both -78 and 38 degrees C followed by quantitation of the residual unfragmented promoter band by SDS-polyacrylamide gel electrophoresis yielded the protomer size, indicating that only one protomer is fragmented by each radiation hit. By following the enzyme activity as a function of dose it was found that only the protomer that has been directly hit and fragmented at -78 degrees C was effectively inactivated. In contrast, at 38 degrees C, it was the whole tetramer that was inactivated. beta-Galactosidase cannot have two different functional units depending on temperature. The inactivation of the whole beta-galactosidase tetramer at 38 degrees C is in fact related to protomer fragmentation but also to the production of stable denatured protomers (detected by gel-filtration HPLC and differential UV spectroscopy) due to energy transfer from fragmented protomers toward unhit protomers.(ABSTRACT TRUNCATED AT 250 WORDS)

Whole MCF‐7 human breast‐cancer cells were irradiated at −78°C in a calibrated Gammacel 6OCo irradiator. Freezing or storing conditions induce neither an alteration of the viability of cells nor a change in estradiol binding activity. Hexosaminidase was used as internal marker, and we measured the radiation inactivation size (RIS) of the estrogen receptor in whole cells. After various cell treatments, the estradiol binding unit always presents a molecular mass of 25 kDa. This value, which corresponds to the size of the defined hormone binding domain of the estrogen receptor, suggests that the energy delivered to the protein by the radiation is efficient to inactivate estradiol binding only when the hit occurs directly in the smaller hormone binding domein.

The nucleic acid sequence of the androgen receptor (AR) gene predicts that the protein structure possesses DNA- and steroid-binding domains that show high degrees of sequence similarity with those of other steroid receptors. Since the steroid-binding domain of the AR corresponds to a 30 kDa portion of the protein, and the AR structure may be monomeric or hetero-oligomeric depending on its transformation state, we have herein determined the AR radiation-inactivation size (RIS) in relation to the molecular structure whose binding activity toward methyltrienolone (R1881) is abolished by a radiation 'hit'. Soluble fractions from whole canine prostatic tissue were used as a source of non-transformed AR. The AR transformation was induced by the addition of 0.6 M-KCl, and these preparations were used together with high-salt nuclear extracts as a source of transformed AR. To maximize the binding activity, molybdate and dithiothreitol were included during AR extraction. Receptor transformation was verified by modifications of both the sedimentation coefficients (from 7.5 S to 4.1 S on sucrose gradients) and molecular masses (from 260 kDa to 115 kDa by gel filtration). The RIS values of the non-transformed and transformed ARs were not statistically different: 92 +/- 19 kDa and 110 +/- 25 kDa respectively. In addition, the inactivation of AR binding activity by radiation was attributed to a loss of binding sites, with no significant change in the Kd. When benzoic acid, a free-electron scavenger, was added together with dithiothreitol before and after irradiation, no change in the RIS value was observed. Thus, in the canine prostate, the RIS value of the AR represents the monomeric protein, independently of its association with other proteins, and this value corresponds to that predicted by cloning studies and photoaffinity-labelling of AR.

We have reinvestigated the use of ionizing radiations to measure the molecular mass of water-soluble or membrane proteins. The test was performed by using the most straightforward aspect of the technique, which consists of SDS/PAGE analysis of the protein-fragmentation process. We found that exposure of purified standard proteins to increasing doses of ionizing radiation causes progressive fragmentation of the native protein into defined peptide patterns. The coloured band corresponding to the intact protein was measured on the SDS gel as a function of dose to determine the dose (D37.t) corresponding to 37% of the initial amount of unfragmented protein deposited on the gel. This led to a calibration curve between 1/D37.t and the known molecular mass of the standard proteins whose best fit gave Mr = 1.77 x 10(6)/D37.t at -78 degrees C, i.e. 35% higher than the generally accepted value at that temperature obtained from inactivation studies. However, we have to conclude that this method is useless to determine the state of aggregation of a protein, since, for all the oligomers tested, the best fit was obtained by using the protomeric molecular mass, suggesting that there is no energy transfer between promoters. Furthermore, SDS greatly increases the fragmentation rate of proteins, which suggests additional calibration problems for membrane proteins in detergent or in the lipid bilayer. But the main drawback of the technique arises from our observation that some proteins behaved anomalously, leading to very large errors in the apparent target size as compared with true molecular mass (up to 100%). It is thus unreliable to apply the radiation method for absolute molecular-mass determination. We then focused on the novel finding that discrete fragmentation of proteins occurs at preferential sites, and this was studied in more detail with aspartate transcarbamylase. N-Terminal sequencing of several radiolysis fragments of the catalytic chain of the enzyme revealed that breaks along the polypeptide chains are localized close to the C-terminal end. Examination of the three-dimensional structure of aspartate transcarbamylase suggests that radiolysis sites (fragile bonds) might be localized in connecting loops.

MCF-7 human breast cancer cells were submitted to the tritiated antiestrogen tamoxifen aziridine, frozen at -170 degrees C, stored and irradiated at -78 degrees C in a calibrated Gammacell 60Co irradiator. A three-step protein extraction procedure provided protein samples for the determination of the target size (TS) of the covalently labelled estrogen receptor (ER). From the TS it is shown that ER bound to an antiestrogen was, in whole cells, part of a 265 kDa polypeptide structure if measured in MCF-7 cells at subconfluency, or of a 360 kDa species in superconfluent cells.

The genetic defect in Gaucher disease consists in a deficiency of a membrane-bound lysosomal acid β-glucosidase. Using the radiation inactivation method, we have previously reported a subunit coupling of the mutated acid β-glucosidase from Gaucher type 1 spleen in contrast to the normal one (Maret, A., Potier, M., Salvayre, R. and Douste-Blazy, L. (1983) FEBS Lett. 160, 93–97). We have used the same method to determine the effect of detergents on subunit coupling or uncoupling of acid β-glucosidase in normal and Gaucher spleens. The hypothesis that detergent activation of β-glucosidase could be due to subunit association or dissociation has been tested. The radiation inactivation size of β-glucosidase in absence of detergent was 71 000 and 135 500 for normal and Gaucher spleen, respectively, whereas the corresponding values in presence of detergent were 84 000 and 169 000. The higher values obtained in the presence of detergent are incompatible with association or dissociation of subunits but correspond to the increase generally observed for proteins irradiated in the presence of Triton X-100.

Radiation-inactivation studies were performed on brush-border-membrane vesicles purified from rat kidney cortex. No alteration of the structural integrity of the vesicles was apparent in electron micrographs of irradiated and unirradiated vesicles. The size distributions of the vesicles were also similar for both populations. The molecular sizes of two-brush-border-membrane enzymes, alkaline phosphatase and 5'-nucleotidase, estimated by the radiation-inactivation technique, were 104800 +/- 3500 and 89,400 +/- 1800 Da respectively. Polyacrylamide-gel-electrophoresis patterns of membrane proteins remained unaltered by the radiation treatment, except in the region of higher-molecular-mass proteins, where destruction of the proteins was visible. The molecular size of two of these proteins was estimated from their mobilities in polyacrylamide gels and was similar to the target size, estimated from densitometric scanning of the gel. Intravesicular volume, estimated by the uptake of D-glucose at equilibrium, was unaffected by irradiation. Uptake of Na+, D-glucose and phosphate were measured in initial-rate conditions to avoid artifacts arising from a decrease in the driving force caused by a modification of membrane permeability. Na+-independent D-glucose and phosphate uptakes were totally unaffected in the dose range used (0-9 Mrad). The Na+-dependent uptake of D-glucose was studied in irradiated vesicles, and the molecular size of the transporter was found to be 288,000 Da. The size of the Na+-dependent phosphate carrier was also estimated, and a value of 234,000 Da was obtained.

In human tissues, the multiple molecular forms of β-glucosidases can be classified in three different groups (1-4).