A specific small-molecule inhibitor of protein kinase CδI activity improves metabolic dysfunction in human adipocytes from obese individuals

The metabolic consequences and sequelae of obesity promote life-threatening morbidities. PKCδI is an important elicitor of inflammation and apoptosis in adipocytes. Here we report increased PKCδI activation via release of its catalytic domain concurrent with increased expression of proinflammatory cytokines in adipocytes from obese individuals. Using a screening strategy of dual recognition of PKCδI isozymes and a caspase-3 binding site on the PKCδI hinge domain with Schrödinger software and molecular dynamics simulations, we identified NP627, an organic small-molecule inhibitor of PKCδI. Characterization of NP627 by surface plasmon resonance (SPR) revealed that PKCδI and NP627 interact with each other with high affinity and specificity, SPR kinetics revealed that NP627 disrupts caspase-3 binding to PKCδI, and in vitro kinase assays demonstrated that NP627 specifically inhibits PKCδI activity. The SPR results also indicated that NP627 affects macromolecular interactions between protein surfaces. Of note, release of the PKCδI catalytic fragment was sufficient to induce apoptosis and inflammation in adipocytes. NP627 treatment of adipocytes from obese individuals significantly inhibited PKCδI catalytic fragment release, decreased inflammation and apoptosis, and significantly improved mitochondrial metabolism. These results indicate that PKCδI is a robust candidate for targeted interventions to manage obesity-associated chronic inflammatory diseases. We propose that NP627 may also be used in other biological systems to better understand the impact of caspase-3-mediated activation of kinase activity.

OR01-6 LncRNA GAS5 Directed Therapeutic Increases Insulin Receptor Expression in Adipocytes

Obesity continues to escalate as a significant public health problem and as the leading preventable cause of death. Obesity is a major risk factor for cardiovascular disease and type 2 diabetes. Obese patients with high morbidities are directed towards bariatric surgeries such as Roux-En-Y gastric bypass (RYGB). These procedures not only result in successful weight loss, but also reduce insulin resistance and lead to resolution of type 2 diabetes mellitus independently of BMI reduction. Type 2 Diabetes Mellitus (T2DM) is polygenic in nature and is frequently associated with insulin resistance and impaired insulin signal transduction. Using the oral glucose tolerance tests (IVGTT), the glycosylated hemoglobin (HbA1c) and the homeostasis model assessment of insulin resistance (HOMA-IR), large cohort studies revealed diabetes resolution in 74-83% of patients who underwent Roux-en-Y procedure. While the underlying genetics of T2DM has been extensively studied, the emphasis has been on genes encoding transcripts that are translated to proteins. However, it is becoming increasingly clear that regulatory noncoding transcripts play an important role in disease manifestation. Long noncoding RNAs (lncRNA) are regulatory RNAs >200nt. We previously showed that lncRNA GAS5 decreased significantly in serum of type 2 diabetes mellitus (T2DM) patients. The data here shows that GAS5 levels are low in obese and diabetic patients and are increased post- RYGB in adipose tissue. Adipose tissue is an important endocrine regulator of energy homeostasis and glucose metabolism. Hence, we sought to decipher the molecular mechanisms underlying the role of GAS5 in T2DM in adipose tissue (AT). We used an unbiased diabetes array to determine the genes affected by knockdown of GAS5 in human AT. Our results show a sharp reduction of insulin receptors A and B with depletion of GAS5. Using CHIP-RIP, we demonstrate that GAS5 binds to promoter of insulin receptor to regulate its expression, and its depletion inhibits glucose uptake and insulin signaling. Towards stabilizing GAS5 levels in adipocytes, a small molecule was identified using OBTC screening strategy. NP-C86 binds to GAS5 with high affinity, increases GAS5 levels and glucose uptake in diabetic patient adipocytes. These results demonstrate that GAS5 plays a pivotal role in resolution of T2DM post RYGB.

Stabilization of lncRNA GAS5 by a Small Molecule and Its Implications in Diabetic Adipocytes

Long noncoding RNA (lncRNA) are regulatory RNAs >200 nt. We previously showed that lncRNA GAS5 decreases significantly in serum of type 2 diabetes mellitus (T2DM) patients. Hence, we sought to decipher the molecular mechanisms underlying the role of GAS5 in T2DM in adipose tissue. Using CHIP-RIP, we demonstrate that GAS5 binds to promoter of insulin receptor to regulate its expression, and its depletion inhibits glucose uptake and insulin signaling. Toward stabilizing GAS5 levels in T2DM, we incorporated a strategy to limit the degradation of GAS5 by blocking the interaction of GAS5 and UPF1 with a small molecule identified using OBTC screening strategy. NP-C86 binds to GAS5 with high affinity, and increases GAS5 levels and glucose uptake in diabetic patient adipocytes. As a broader impact, NP-C86 may be used as a molecular probe to investigate the intricacies of GAS5 in relevant biological systems as it offers specificity, efficient cellular uptake and is non-cytotoxic.

MALAT1 in Human Adipose Stem Cells Modulates Survival and Alternative Splicing of PKCδII in HT22 Cells

Brain injury may be caused by trauma or may occur in stroke and neurodegenerative diseases. Because the central nervous system is unable to regenerate efficiently, there is utmost interest in the use of stem cells to promote neuronal survival. Of interest here are human adipose-derived stem cells (hASCs), which secrete factors that enhance regeneration and survival of neurons in sites of injury. We evaluated the effect of hASC secretome on immortalized mouse hippocampal cell line (HT22) after injury. Protein kinase C δ (PKCδ) activates survival and proliferation in neurons and is implicated in memory. We previously showed that alternatively spliced PKCδII enhances neuronal survival via B-cell lymphoma 2 Bcl2 in HT22 neuronal cells. Our results demonstrate that following injury, treatment with exosomes from the hASC secretome increases expression of PKCδII in HT22 cells and increases neuronal survival and proliferation. Specifically, we demonstrate that metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a long noncoding RNA contained in the hASC exosomes mediates PKCδII splicing, thereby increasing neuronal survival. Using antisense oligonucleotides for MALAT1 and RNA immunoprecipitation assays, we demonstrate that MALAT1 recruits splice factor serine-arginine-rich splice factor 2 (SRSF2) to promote alternative splicing of PKCδII. Finally, we evaluated the role of insulin in enhancing hASC-mediated neuronal survival and demonstrated that insulin treatment dramatically increases the association of MALAT1 and SRSF2 and substantially increases survival and proliferation after injury in HT22 cells. In conclusion, we demonstrate the mechanism of action of hASC exosomes in increasing neuronal survival. This effect of hASC exosomes to promote wound healing can be further enhanced by insulin treatment in HT22 cells.

Adipose-derived stem cells from lean and obese humans show depot specific differences in their stem cell markers, exosome contents and senescence: role of protein kinase C delta (PKCδ) in adipose stem cell niche

BACKGROUND

Adipose-derived stem cells (ASC) and its exosomes are gaining utmost importance in the field of regenerative medicine. The ASCs tested for their potential in wound healing are predominantly derived from the subcutaneous depot of lean donors. However, it is important to characterize the ASC derived from different adipose depots as these depots have clinically distinct roles.

METHODS

We characterized the ASC derived from subcutaneous and omental depots from a lean donor (sc-ASCn and om-ASCn) and compared it to the ASC derived from an obese donor (sc-ASCo and om-ASCo) using flow cytometry and real time qPCR.

RESULTS

We show that stem cell markers Oct4, Sal4, Sox15, KLF4 and BMI1 have distinct expression patterns in each ASC. We evaluated the secretome of the ASC and characterized their secreted exosomes. We show long noncoding RNAs (lncRNAs) are secreted by ASC and their expression varied between the ASC's derived from different depots. Protein kinase C delta (PKCδ) regulates the mitogenic signals in stem cells. We evaluated the effect of silencing PKCδ in sc-ASCn, om-ASCn, sc-ASCo and om-ASCo. Using β-galactosidase staining, we evaluated the percentage of senescent cells in sc-ASCn, om-ASCn, sc-ASCo and om-ASCo. Our results also indicated that silencing PKCδ increases the percentage of senescent cells.

CONCLUSIONS

Our case-specific study demonstrates a role of PKCδ in maintaining the adipose stem cell niche and importantly demonstrates depot-specific differences in adipose stem cells and their exosome content.

Protein kinase C delta (PKCδ) splice variant modulates senescence via hTERT in adipose-derived stem cells

BACKGROUND

Adipose-derived stem cells (ADSC) were isolated and characterized from lean and obese subjects. We previously reported that distinct differences were observed in differentiating lean and obese preadipocytes. Protein kinase C delta (PKCδ) is alternatively spliced and has important roles in apoptosis. PKCδI promotes apoptosis and PKCδVIII promotes survival. Our previous data indicated an increase in the survival kinase, PKCδVIII in ADSC derived from an obese donor. We also determined that obese adipocytes were resistant to apoptosis. Here, we determine the relationship between a survival kinase PKCδVIII and hTERT expression in adipose derived stem cells from a lean and obese subject.

METHODS

We evaluated the telomerase activity and human telomerase reverse transcriptase (hTERT) expression in lean and obese ADSC. The lean and obese ADSC were purchased as cryopreserved cells from ZenBio™ (Research Triangle Park, NC, USA). Analyses were performed using PRISM™ software and analyzed using two-tailed Student's t-test.

RESULTS

We observed an increase in telomerase in differentiating obese ADSC using western blot analysis. We determined the levels of hTERT splice variants. hTERT α+/β+ splice variant was increased after transfected of PKCδVIII. We next determined whether PKCδVIII over-expression affected the levels of telomerase. The results indicate an increase in telomerase with PKCδVIII over-expression.

CONCLUSIONS

Over-expression of PKCδVIII in lean ADSC substantially increased expression of hTERT and telomerase. The decreased senescence seen in obese ADSC may in part be attributed to PKCδVIII. Obese ADSC undergo lower senescence and may have increased growth potential. These results propose a larger epigenetic modification in obese ADSC compared to lean ADSC.

Diet-induced obesity associated with steatosis, oxidative stress, and inflammation in liver

BACKGROUND

Obesity induces steatosis and increases oxidative stress, as well as chronic inflammation in the liver. The balance between lipogenesis and lipolysis is disrupted in obese animals. At a cellular level, the changes in metabolic sensors and energy regulators are poorly understood. We hypothesized that diet-induced steatosis increases oxidative stress, inflammation, and changes the metabolic regulators to promote energy storage in mice. The setting was a university-affiliated basic science research laboratory.

METHODS

Four-week-old C57BL mice were fed a high-fat diet (n = 8) or regular chow (n = 8) for 7 weeks. The liver sections were stained for fat content and immunofluorescence. Liver homogenates were used for protein analysis by immunoblotting and mRNA analysis by reverse transcriptase-polymerase chain reaction. The gels were quantified using densitometry P ≤ .05 was considered significant.

RESULTS

The high-fat diet upregulated protein kinase-C atypical isoforms ζ and λ and decreased glucose tolerance and the interaction of insulin receptor substrate 2 with phosphoinositide kinase-3. The high-fat diet increased the transcriptional factors liver X receptor (4321 ± 98 versus 2981 ± 80) and carbohydrate response element-binding protein (5132 ± 135 versus 3076 ± 91), the lipogenesis genes fatty acid binding protein 5, stearoyl-co-enzyme A desaturase-1, and acetyl-co-enzyme A carboxylase protein, and fatty acid synthesis. The high-fat diet decreased 5'-adenosine monophosphate-activated protein kinase (2561 ± 78 versus 1765 ± 65), glucokinase-3β (2.214 ± 34 versus 3356 ± 86), and SIRT1 (2015 ± 76 versus 3567 ± 104) and increased tumor necrosis factor-α (3415 ± 112 versus 2042 ± 65), nuclear factor kappa B (5123 ± 201 versus 2562 ± 103), cyclooxygenase-2 (4230 ± 113 versus 2473 ± 98), nicotinamide-adenine dinucleotide phosphate oxidase (3501 ± 106 versus 1600 ± 69) and reactive oxygen species production (all P < .001, obese mice versus lean mice).

CONCLUSION

A high-fat diet impairs glucose tolerance and hepatic insulin signaling, upregulates transcriptional and translational activities that promote lipogenesis, cytokine production, proinflammatory signaling, and oxidative stress, and downregulates lipolysis. Understanding the complex cellular signals triggered by obesity might have profound clinical implications.

Validation of the Obesity Surgery Mortality Risk Score in a Multicenter Study Proves It Stratifies Mortality Risk in Patients Undergoing Gastric Bypass for Morbid Obesity

BACKGROUND

A scoring system for clinical assessment of mortality risk has been previously proposed for bariatric surgery (Demaria EJ, Portenier D, Wolfe L, Surg Obes Relat Dis. 2007;3:34-40.). The Obesity Surgery Mortality Risk Score (OS-MRS) was developed from a single institution experience of 2075 patients. The current study provides multicenter validation of the value of the OS-MRS. The OS-MRS assigns 1 point to each of 5 preoperative variables, including body mass index>or=50 kg/m2, male gender, hypertension, known risk factors for pulmonary embolism (previous thromboembolism, preoperative vena cava filter, hypoventilation, pulmonary hypertension), and age>or=45 years. Patients with total score of 0 to 1 are classified as 'A' (lowest) risk group, score 2 to 3 as 'B' (intermediate) risk group, and score 4 to 5 as 'C' (high) risk group.

METHODS

Prospectively-collected data from 4431 consecutive patients undergoing a primary gastric bypass at 4 bariatric programs recruited to validate the proposed system were analyzed to assess OS-MRS as a means of stratifying surgical mortality risk.

RESULTS

There were 33 total deaths for an overall mortality for the validation cohort of 0.7% consistent with published standards. Mortality for 2164 class A patients was 0.2%, for 2142 class B patients was 1.1%, and for 125 class C patients was 2.4%. Mortality was significantly different between each of the class A, B, and C groupings (P<0.05, chi2). Mortality was 5-fold greater in the class B group than in class A. Only 6 patients with all 5 risk factors were identified. Class C patients (n=125, 3% of total cohort) were characterized by a 12-fold greater mortality than the lowest risk group (A) and a disproportionate 9% of all mortalities.

CONCLUSION

The OS-MRS was found to stratify mortality risk in 4431 patients from 4 validation centers that were nonparticipants in the original defining cohort study. The score represents the first validated scoring system for risk stratification in bariatric surgery and is anticipated to aid informed consent discussions, guide surgical decision-making, and allow standardization of outcome comparisons between treatment centers.

Transcatheter Arterial Chemoembolization with or without Radiofrequency Ablation in the Management of Patients with Advanced Hepatic Malignancy

Transcatheter arterial chemoembolization (TACE) is efficacious against hepatic malignancies by rendering tumors ischemic while delivering high-dose chemotherapy. The added benefit of radiofrequency ablation (RFA) has not been determined. We sought to review our experience with TACE with or without RFA in the treatment of hepatocellular carcinoma and colorectal liver metastases in patients not amenable to resection. TACE and RFA were undertaken in 13 patients with hepatocellular carcinoma (n = 7) or colorectal liver metastases (n = 6). Concurrently 24 patients underwent TACE alone for hepatocellular carcinoma (n = 15) or colorectal liver metastases (n = 9). Patients undergoing TACE with or without RFA were similar in age, gender, and diagnosis. Overall follow-up was 9.1 months ± 7.1. One-year survival was greater in patients undergoing TACE with RFA than with TACE alone (100% vs 67%, P = 0.04). Mean survival was longer after TACE with RFA compared with TACE alone (25.3 months ± 15.9 vs 11.4 months ± 7.3, P < 0.05). No patients suffered significant complications. The addition of RFA to TACE improves survival in patients with unresectable primary or metastatic hepatic malignancies. RFA with TACE should be in the armamentarium of surgeons caring for patients with malignant liver lesions.

Transcatheter arterial chemoembolization with or without radiofrequency ablation in the management of patients with advanced hepatic malignancy

Transcatheter arterial chemoembolization (TACE) is efficacious against hepatic malignancies by rendering tumors ischemic while delivering high-dose chemotherapy. The added benefit of radiofrequency ablation (RFA) has not been determined. We sought to review our experience with TACE with or without RFA in the treatment of hepatocellular carcinoma and colorectal liver metastases in patients not amenable to resection. TACE and RFA were undertaken in 13 patients with hepatocellular carcinoma (n = 7) or colorectal liver metastases (n = 6). Concurrently 24 patients underwent TACE alone for hepatocellular carcinoma (n = 15) or colorectal liver metastases (n = 9). Patients undergoing TACE with or without RFA were similar in age, gender, and diagnosis. Overall follow-up was 9.1 months +/- 7.1. One-year survival was greater in patients undergoing TACE with RFA than with TACE alone (100% vs 67%, P = 0.04). Mean survival was longer after TACE with RFA compared with TACE alone (25.3 months +/- 15.9 vs 11.4 months +/- 7.3, P < 0.05). No patients suffered significant complications. The addition of RFA to TACE improves survival in patients with unresectable primary or metastatic hepatic malignancies. RFA with TACE should be in the armamentarium of surgeons caring for patients with malignant liver lesions.

Laparoscopic revision of failed antireflux operations

BACKGROUND

A small number of patients fail fundoplication and require reoperation. Laparoscopic techniques have been applied to reoperative fundoplications. We reviewed our experience with reoperative laparoscopic fundoplication.

METHODS

Reoperative laparoscopic fundoplication was undertaken in 28 patients, 19 F and 9 M, of mean age 56 years +/- 12. Previous antireflux procedures included 19 open and 12 laparoscopic antireflux operations.

RESULTS

Symptoms were heartburn (90%), dysphagia (35%), and atypical symptoms (30%%). The mean interval from antireflux procedure to revision was 13 months +/- 4.2. The mean DeMeester score was 78+/-32 (normal 14.7). Eighteen patients (64%) had hiatal breakdown, 17 (60%) had wrap failure, 2 (7%) had slipped Nissen, 3 (11%) had paraesophageal hernias, and 1 (3%) had an excessively tight wrap. Twenty-five revisions were completed laparoscopically, while 3 patients required conversion to the open technique. Complications occurred in 9 of 17 (53%) patients failing previous open fundoplications and in 4 of 12 patients (33%) failing previous laparoscopic fundoplications and included 15 gastrotomies and 1 esophagotomy, all repaired laparoscopically, 3 postoperative gastric leaks, and 4 pneumothoraces requiring tube thoracostomy. No deaths occurred. Median length of stay was 5 days (range 2-90 days). At a mean follow-up of 20 months +/- 17, 2 patients (7%) have failed revision of their fundoplications, with the rest of the patients being essentially asymptomatic (93%).

CONCLUSIONS

The results achieved with reoperative laparoscopic fundoplication are similar to those of primary laparoscopic fundoplications. Laparoscopic reoperations, particularly of primary open fundoplication, can be technically challenging and fraught with complications.

Videoscopic Heller myotomy for achalasia--results beyond short-term follow-up

BACKGROUND

Heller myotomy has long been utilized for patients failing nonoperative management of achalasia. Videoscopy has been advocated to decrease the morbidity of Heller myotomy; however, few reports document outcome beyond 1 year after videoscopic Heller myotomy.

PURPOSE

To determine perioperative morbidity, relief of dysphagia, and the incidence of postoperative reflux symptoms following videoscopic Heller myotomy with follow-up to over 4 years.

METHODS

Patients with achalasia documented by barium esophogram and esophageal manometry underwent videoscopic Heller myotomy beginning in 1992. Intraoperative peroral endoscopy was utilized to guide the cephalad and caudad extent of myotomy. A barium esophogram was undertaken in the immediate postoperative period to evaluate for subclinical leak and assess esophageal emptying.

RESULTS

Seventy-eight patients underwent videoscopic Heller myotomy. The mean age was 51 years +/- 19 (range 14 to 91). Most (62%) patients had undergone pneumatic dilation prior to surgical consultation and 54% had previous botox injections. All patients complained of dysphagia and 40% had symptoms of heartburn prior to myotomy. After myotomy, 91% of patients stated that their swallowing was improved with myotomy. Thirteen patients (18%) experience heartburn more than once per week after myotomy. The average length of stay was 2 +/- 2 days, with 72% of patients spending 2 days or fewer in the hospital. Six (7.7%) major complications occurred: five esophageal perforations and one enterotomy without long-term sequellae. Three procedures (3.8%) were converted to "open" procedures. No deaths occurred. We conclude that videoscopic Heller myotomy is safe and efficacious, with low morbidity and mortality. Videoscopic myotomy provides relief beyond the short term for dysphagia due to achalasia with minimal reflux symptoms. We advocate videoscopic Heller myotomy in the treatment of severe dysphagia due to achalasia not adequately palliated by or amenable to nonoperative management.

Role of the vagal branches to the proximal stomach in mediating gastric distention-induced disruption of canine interdigestive upper gut motility

Previous experiments from our laboratory have shown that the vagus nerves mediate proximal gastric distention-induced disruption of interdigestive motor patterns in the upper gut of dogs. Our aim was to determine the role of vagal innervation of the proximal stomach in mediating the response to nonnutrient proximal gastric distention. Five dogs underwent proximal gastric vagotomy (PGV) and placement of electrodes and manometry catheters on the antrum and the upper small intestine. Proximal gastric distention for 5 hr was achieved by inflating a thin, compliant bag in the proximal stomach. Four volumes of distention stimulus (0, 1.5, 12.5, and 25 ml/kg) were tested. As with total abdominal vagotomy, intragastric stimulus volumes of 12.5 and 25 ml/kg after PGV no longer inhibited cycling of the migrating motor complex in the stomach, duodenum, proximal jejunum, and distal jejunum. Volumes of 12.5 and 25 ml/kg did, however, on occasion, lead to the absence of phase III activity in the stomach or the duodenum when it would have been expected to precede phase III activity in the jejunum; this effect did not occur in the jejunum. These findings with a nonnutrient stimulus suggest that vagal branches to the proximal stomach might mediate, in part, the postprandial changes in upper gut motility in response to gastric distention by ingestion of a meal.

Absorption in the isolated bowel segment

An isolated bowel segment (IBS) is a viable mesenteric segment of intestine. This study was undertaken to investigate the effects of mesenteric vascular and neural supply on intestinal absorption. Ten rats were used for leucine absorption and another 10 for glucose absorption experiments. L-leucine, 12 ml of 15.0 mM/L, or 3.0 mM/L of D-glucose solution were recirculated through the IBS (n = 5) and rat jejunum that underwent sham operation (n = 5) at 2.56 ml/min for 90 min. Absorption was expressed as millimoles of leucine or glucose per gram of mucosal protein. The Student's t test was used for statistical analysis; a p < or = 0.05 was considered significant. The net absorption of L-leucine was 36.20 +/- 3.31 mM/g of mucosal protein in the IBS and 15.52 +/- 1.48 mM/g of mucosal protein in the control group (p < 0.001). The net absorption of D-glucose was 3.82 +/- 0.26 mM/g of mucosal protein in the experimental group and 4.34 +/- 0.31 mM/g of mucosal protein in the control group (p = 0.02). This study concludes that absorption of leucine and glucose in the IBS is preserved after mesenteric division.

The isolated bowel segment (Iowa model II): motility across the anastomosis with or without mesenteric division

In previous reports, anastomosis has been shown to disrupt the myoelectric activity of the bowel. However, these studies have failed to delineate the role of the extrinsic nerves. Using an isolated bowel segment (IBS) and an amesenteric bowel segment (ABS), motility was evaluated by myoelectric recording across a bowel anastomosis. Ten rats were divided equally into the experimental group with the IBS and the control group with the ABS. In the IBS group, an 8-cm segment of jejunum was divided, reanastomosed, and coapted to the liver margin (Iowa model II). In the ABS group, an 8-cm segment of jejunum was coapted to the liver margin without disruption of bowel continuity (Iowa model II variant). Two weeks later, bipolar electrodes were implanted in the IBS and ABS, and normal jejunum in both groups. Mesenteric division (MD) was performed 4 weeks later to eliminate extrinsic innervation. Myoelectrical recordings were taken 2 weeks before and after MD. In the control group with IBS, incoordination in the propagation of the migrating motor complex (MMC) and reduction in the frequency of slow waves (FSW) were observed across the anastomosis and were unchanged by MD. In the control group with the ABS, the MMC and FSW were identical to that in the normal jejunum and were unaffected by MD. In both groups postprandial inhibition of the MMC was the same as in the normal jejunum and was unaffected by MD. This study confirms that incoordination in propagation of the MMC and reduction in FSW occur across a bowel anastomosis, and elimination of extrinsic innervation does not affect the autonomy of these changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of enzymatic treatment on calcium absorption by small intestine: a comparative study between rat and rabbit transport mechanisms

Calcium absorption by the small intestine of rat and rabbit reached steady state after 60 min of incubation with intracellular to extracellular ratio of 2.0. Trypsin and neuraminidase significantly inhibited (P less than 0.05) calcium accumulation in rat small intestine. These enzymes showed no significant effect (P greater than 0.05) on calcium transport across rabbit small intestine. The inhibitory action of trypsin and neuraminidase on calcium accumulation by the rat small intestine does not involve the influx of calcium into the intestinal cells.