Congenital rickets--a patient report

We present a premature newborn with congenital rickets, born to a mother with untreated chronic renal insufficiency. X-ray films showed blurred metaphyseal ends and decreased bone density in the femurs and ribs. With treatment including calcium, phosphate, and vitamin D, her rickets healed and she grew normally.

Weekly 24-hour infusion of high-dose 5-fluorouracil and leucovorin in the treatment of advanced gastric cancers. An effective and low-toxic regimen for patients with poor general condition

Systemic chemotherapy for advanced gastric cancer is frequently associated with significant treatment-related toxicity, which is particularly serve in patients presenting with a poor general condition. A search for effective and low-toxic regimens for this group of patients is mandatory. A weekly 24-hour infusion of high-dose 5-fluorouracil (5-FU) and leucovorin (HDFL) has previously been demonstrated to be an effective treatment for advanced colorectal cancer with minimal toxicity. In the past 3 years, this regimen has been tested at our institutes in patients with advanced gastric cancer, the general condition of whom had made the use of intensive combination chemotherapy impossible. The regimen consisted of a weekly 24-hour infusion of 2,600 mg/m2 of 5-FU and 300 mg/m2 of leucovorin. From August 1992 to December 1995, 34 patients had been treated with this regimen for a total of 488 courses (average: 14.4 per patient). Hematological toxicity of this regimen was minimal, with grade 3 or 4 leukopenia developing in only 1 (2.9%) patient. Other nonhematological toxicities were also negligible except a reversible neurotoxicity which developed in 2 patients. Twenty-five patients were eligible for response analysis. One complete response, 11 partial responses, 5 stable diseases, and 8 progressive diseases were observed. The response rate was 48% (32-72%, 95% CI). The median overall survival (OS) of the whole group was 7 months (range: 1-18+). The median OS and time to progression of the responders were 8.5 months (range: 2-18) and 5 months (range: 2-10+), respectively. The palliative effect was satisfactory with the Karnofsky performance status of the responders improving from a median of 50% (range: 20-90%) to 70% (range: 50-100%). Our retrospective data suggested that HDFL is an effective and low-toxic palliative treatment even in patients with a very poor general condition. We advocated that this regimen should be further tested in ordinary patients with advanced gastric cancer.

Effect of glyoxylate on the function of the calcitriol receptor and vitamin D metabolism

The biological action of calcitriol is mostly mediated through the interaction of the calcitriol receptor (VDR) with vitamin D response elements (VDREs) of target genes. These interactions produce special proteins that carry out the biological activities of calcitriol. Recently, we showed that the interaction of VDRs with VDREs is inhibited by uremic toxins. We hypothesize that uremic toxins that contain aldehyde or ketone groups potentially could form Schiff bases with lysine residues of the VDR DNA binding domain and inhibit VDR interaction with VDREs. We therefore chose glyoxylate, a compound which has an aldehyde group, to test this hypothesis. In vitro glyoxylate inhibited VDR binding to the osteocalcin and osteopontin VDREs as assessed by electrophoretic mobility shift assay and the inhibition was reversed when glyoxylate was preincubated with lysine. Further, this chemical compound also blocked the induction of chloramphenicol acetyltransferase (CAT) enzyme induced by calcitriol in cells transfected with a calcitriol responsive CAT reporter gene. Since induction of 24-hydroxylase synthesis is a VDR regulated process, we also studied the effect of glyoxylate on the activity of intestinal 24-hydroxylase in rats. This enzyme activity was suppressed in rats infused with glyoxylate. Taken together, our study suggests that glyoxylate could inhibit the interaction of VDR with VDREs and alter the biological action of calcitriol.

Clinical experience with early enteral feeding in very-low-birth-weight infants

The primary objective of this study was to evaluate the safety and benefit of early enteral feeding in very-low-birth-weight (VLBW) infants without parenteral nutrition. Weight gain, feeding intolerance, nosocomial infection rate and a postnatal growth curve were recorded for 61 VLBW premature infants who were admitted to the Neonatal Intensive Care Unit of Mackay Memorial Hospital from September 1, 1995 to February 28, 1997. Nine infants were unable to complete the study and three were excluded because of severe bronchopulmonary dysplasia; therefore only 49 infants could be evaluated. They were divided into two groups based on birth weight: 1001 gm to 1250 gm (Group A, mean birth weight 1153 +/- 64 gm, mean gestational age 29.0 +/- 2.2 weeks), and less than or equal to 1000 gm (Group B, mean birth weight 911 +/- 82 gm, mean gestational age 27.1 +/- 1.5 weeks). They received breast milk or premature formula by intermittent nasogastric or continuous nasogastric feeding. Growth was followed over the first 30 postnatal days. Group A reached 100 kcal/kg/day of enteral feeding at a mean age of 17 days as compared with a mean age of 20 days for group B. Infants regained their birth weight at 20 and 25 days in Groups A and B, respectively. By the 30th postnatal day, weight gain exceeded birth weight by 218.2 +/- 143.1 gm and 95.3 +/- 81.5 gm in groups A and B respectively. No definite episodes of necrotizing enterocolitis (NEC) developed. Two cases of Escherichia coli sepsis and one of Klebsiella sepsis occurred. The conclusion was that early enteral feeding in very-low-birth-weight infants does not increase the risk of NEC. It was also demonstrated that enteral feeding alone can produce biphasic postnatal growth curves in very-low-birth-weight infants. Although early enteral feeding was well tolerated in the study infants, the occurrence of feeding intolerance in some (36%) would suggest that additional parenteral nutrition may benefit some infants until full enteral feeding can be achieved.

Effect of glucose on the function of the calcitriol receptor and vitamin D metabolism

The genomic action of calcitriol is mediated through the interaction of the calcitriol receptor (VDR) with vitamin D response elements (VDREs) of the target genes. It has been proposed that chemicals capable of Schiff base formation with the VDR potentially could alter the physiological function of VDR and calcitriol metabolism. Since glucose has been shown to form Schiff bases with proteins, we tested the hypothesis that glucose could influence the function of VDR and thereby alter calcitriol metabolism. Glucose 6-phosphate inhibited VDR binding to the osteocalcin VDRE and chemically modified the DNA binding domain or the dimerization domain of the VDR in vitro. Further, glucose also blocked the production of chloramphenicol acetyltransferase (CAT) enzyme induced by calcitriol in cells transfected with a constructed VDRE attached to a CAT reporter gene. Hyperglycemia induced by glucose infusion or by streptozotocin in normal rats significantly reduced intestinal 1 alpha, 25-dihydroxyvitamin D-24-hydroxylase activity. Taken together, these findings are consistent with the hypothesis that glucose could interact with the VDR to impair its DNA binding and function within cells.

Robinow syndrome: report of one case

We report a 2-month-old infant with Robinow syndrome. Clinical manifestations included short stature, characteristic facies, mesomelic brachymelia, brachydactyly, camptodactyly, duplication of thumbs, hypoplasia of clitoris, and deformed pronated foot. A cytogenetic study revealed a normal female karyotype. Chest radiography showed rib anomalies, a vertebral anomaly in T8, narrowing of interpedicular distances and flaring with slight thickening of the bone cortex in the bilateral humeral bone. Hand and foot radiography showed generalized shortening include unequal size of metacarpal, metatarsal and phalangeal bones. In our case, sporadic or autosomal recessive inheritance was most likely. The literature is reviewed.

Are we mismanaging calcium and phosphate metabolism in renal failure?

Secondary hyperparathyroidism and renal osteodystrophy are the consequences of abnormal calcium, phosphate, and calcitriol metabolism ensuing from renal failure. Evidence suggests that calcium balance tends to become negative as we grow older than 35 years of age; however, the current dialysis modalities provide patients regardless of age with excessive calcium during dialysis. Administration of calcitriol in the management of hyperparathyroidism further increases the calcium and phosphate absorption. Furthermore, the current thrice-weekly renal replacement therapies fail to remove the daily absorbed phosphate, and we have to use calcium carbonate as a primary phosphate-binding agent to reduce intestinal phosphate absorption. The large calcium mass transfer and phosphate retention could lead to soft tissue calcification, especially in older end-stage renal disease (ESRD) patients. Consequently, only by maintaining a negative calcium balance during renal replacement therapy can we safely use calcitriol and calcium carbonate for the management of secondary hyperparathyroidism. Recent studies have indicated that phosphate restriction alone independent of plasma calcitriol or calcium can lower plasma parathyroid hormone (PTH) in renal failure and prevent hyperplasia of parathyroid glands. Therefore, phosphate control perhaps is the most important means to prevent secondary hyperparathyroidism. Previous studies have shown that ferric compounds are potent phosphate-binding agents; hence, these compounds warrant further trial in the management of phosphate metabolism in renal failure.

Thymic carcinoma with autoimmune syndrome: successful treatment with weekly infusional high-dose 5-fluorouracil and leucovorin

Thymic carcinoma is known for its poor clinical outcome and unsatisfactory response to conventional chemotherapy. A 53-year-old woman was diagnosed as having metastatic thymic carcinoma in 1989. She received systemic chemotherapy containing cisplatin, doxorubicin, and cyclophosphamide, and involved-field radiotherapy. A durable complete remission was achieved and lasted for 4 years. When the disease recurred in 1995, she was found to have an autoimmune syndrome in addition to pleural effusion, a posterior mediastinal mass and a left adrenal mass. The autoimmune manifestations were seen as scleroderma, high titers of rheumatoid factor and anti-nuclear antibody. We adopted a novel HDFL regimen, which is composed of weekly 24-hour infusion of high-dose 5-fluorouracil and leucovorin, for this patient. Complete remission was achieved again, and autoimmune syndrome was well controlled.

Characterization of DNA adducts formed by cyclopenta[cd]pyrene epoxide

Cyclopenta[cd]pyrene (CPP) is a ubiquitous environmental pollutant whose 3,4-epoxide (CPPE) is generally regarded as its ultimate carcinogenic metabolite. The present study was undertaken to determine the structures of major DNA adducts formed by CPPE in vitro. Incorporation of specific radiolabeled bases into calf thymus DNA prior to reaction with CPPE demonstrated that the major adducts were formed by guanine, while minor adducts were formed by adenine and cytosine. Unmodified DNA was reacted with [3H]CPPE and the deoxynucleoside adducts obtained were compared chromatographically with the products obtained by reaction of CPPE with 2'-deoxyguanosine (dGuo). Two dGuo adducts from the latter reaction were identified by 1H-NMR, fast atom bombardment mass spectrometry, and circular dichroism as diastereoisomers of cis-3-(deoxyguanosin-N2-yl)-4-hydroxy-3,4-dihydroCPP. Other products that may have included the isomeric trans-N2-dGuo adduct were formed in the reaction. The major adduct fraction in the DNA digest, accounting for over 70% of the total, was chromatographically indistinguishable from the two cis dGuo-N2 adducts. A second DNA adduct fraction was observed, which appeared also to be formed by reaction with guanine as indicated by experiments in which DNA containing [3H]guanine was reacted with unlabeled CPPE. The results confirm that guanine is the major target in DNA for reaction with CPPE and are the first proof of structure for a CPPE-deoxynucleoside adduct.

Functional characterization of a chicken major histocompatibility complex class II B gene promoter

A 0.7 kilobase (kb) DNA fragment from the 5' flanking region of a chicken major histocompatibility complex (MHC) class II B gene was cloned into chloramphenicol acetyltransferase (CAT) reporter vectors and was transfected into a chicken macrophage cell line that expresses a low level of MHC class II antigens. Positive orientation-dependent promoter activity of the chicken DNA was evident in a reporter construct containing an SV40 enhancer. Deletion analysis of this 0.7 kb DNA fragment revealed a short fragment in the 3' end that was crucial for the promoter function and negative regulatory elements (NRE) located further upstream. The conserved MHC class II X and Y boxes did not have a significant effect on promoter activity. Sequence analysis of the 0.7 kb class II B gene upstream region suggests possible involvement of interferon (IFN), E twenty-six specific (ETS)-related proteins, and other factors in regulating this promoter. A chicken T-cell line culture supernatant increased surface expression of MHC class II antigens, as well as class II promoter activity, in this macrophage cell line. This first functional characterization of a chicken MHC class II B gene promoter will aid in understanding the regulatory mechanisms that control the expression of these genes.

Glutathione-S-transferase induces murine dermatitis that resembles human atopic dermatitis

BACKGROUND

The molecular and functional basis of allergen-induced inflammation seen in atopic dermatitis (AD) remains undefined.

OBJECTIVE

The objective of this study is to establish a murine model to dissect the pathological mechanisms of inflammatory reactions leading to the development of AD.

METHODS

An inbred strain of mice, BALB/c, when injected peritoneally with 30 micrograms of recombinant Sj26 protein (rSj26), a glutathione-S-transferase of Schistosoma japonicum worm, developed systematic dermatitis 21 days after immunization. The pathology of the dermatitis was examined by histological evaluation and immunostaining. The immediate skin hypersensitivity was demonstrated by serum transfer and skin test. Epicutaneous patch test was used to demonstrate the antigen-specific late phase response.

RESULTS

Significant responses of rSj26-specific IgE were detected 2 weeks after immunization, and such changes paralleled formation of skin lesions. The diseased skin pathology showed inflammatory changes such as infiltration of mononuclear cells and eosinophils in the dermis and mild spongiosis in the epidermis. Numerous IgE bearing cells were also detected in the dermis. Peripheral blood showed eosinophilia at the same time. In addition, rSj26-specific positive skin test and epicutaneous patch test could be demonstrated in rSj26-sensitized mice.

CONCLUSIONS

These results suggest that rSj26 is capable of eliciting atopic dermatitis-like lesions in BALB/c mice. This can be a useful animal model for elucidating allergen-induced immune responses and the development of various therapeutic interventions of atopic dermatitis in humans.

Effect of Schiff base formation on the function of the calcitriol receptor

The genomic action of calcitriol is mediated through the interaction of the calcitriol receptor (VDR) with vitamin D response elements (VDREs) of the target genes. We have shown that the interaction of VDRs with VDREs is inhibited by uremic toxins. We hypothesize that uremic toxins form Schiff bases with the lysine residues of the VDR DNA binding domain and inhibit the VDR interaction with the VDRE. In this study, pyridoxal 5'-phosphate was used as a probe to test Schiff base formation as the inhibitory mechanism, since it forms Schiff bases with steroid receptors. Pyridoxal 5'-phosphate inhibited the VDR binding to the VDREs and chemically modified the DNA binding domain of the VDR in vitro. The inhibition was reversed when pyridoxal 5'-phosphate was preincubated with lysine. Further, this chemical agent also blocked the production of chloramphenicol acetyltransferase (CAT) enzyme induced by calcitriol in cells transfected with a constructed VDRE attached to a CAT reporter gene. This finding is consistent with the hypothesis that pyridoxal 5'-phosphate could interact with the VDR and impair its DNA binding within cells. Since induction of 24-hydroxylase synthesis is a receptor mediated process, we studied the effect of pyridoxal 5'-phosphate on the synthesis of renal 24-hydroxylase in rats. When pyridoxal 5'-phosphate was infused to rats, renal 24-hydroxylase activity was suppressed, consequently, degradation of calcitriol was also reduced in these animals. Thus, chemicals capable of Schiff base formation potentially could alter the physiological function of VDR and calcitriol.

Dynamic analysis and geometry models for the design of bi-leaflet prosthetic mechanical heart valves

This paper provides new geometry definitions for the axi-symmetric stiffening (or sewing) ring, as part of a bi-leaflet prosthetic heart valve, and presents a dynamic behaviour analysis of the leaflet. An optimal stiffening ring geometry may be constructed by considering the point of flow separation on the stiffening ring (measured in the downstream coordinate), the effective orifice area of the stiffening ring and the associated dynamic behaviour of the leaflet. The dynamic model is accomplished by utilizing a second-order rotating system to simulate the opening and closing characteristics of the leaflet. The moments due to the aerodynamic loads are evaluated from an irrotational inviscid flow model, coupled with boundary layer theory, modelling the internal flow phenomena of the bi-leaflet heart valve implanted in the aortic root. It has been shown that this internal flow model provides the correct evaluation of lift and induced drag and the subsequent dynamic characteristics.

Inhibition of specific IgE response in vivo by allergen-gene transfer

DNA immunization has been an attractive approach in altering the host immune response to antigen. To examine the utility of DNA immunization in allergic response, we examined the in vivo efficacy of an 'allergen-gene immunization' approach in the modulation of allergen-specific IgE responses in mice. Our results showed first that I.m. injection of a gene construct (pCMVD) containing an important house dust mite allergen gene (Dermatophagoides pteronyssinus group 5 allergen; Der p 5) results in the induction of Der p 5-specific IgG antibodies, but not IgE antibody. We next examined the effect of transduced allergen gene on the expression of specific IgE response in mice after i.p. challenge with recombinant Der p 5 (rDer p 5). Both vector (mock) control- and pCMVD-treated mice were i.p. sensitized with rDer p 5 at 3 weeks after injection of gene construct. Results showed that there is a 90% reduction in the level of specific IgE in pCMVD-treated mice when compared with mock-treated mice. Furthermore, the suppression of specific IgE response can be adoptively transferred with CD8+ T cells from pCMVD-treated mice and such inhibition is in an antigen-specific manner, since the level of specific IgE to an irrelevant allergen, Der p 1, remained unchanged in comparison to that of the mock-treated group. In addition, Der p 5-specific CD8+ T cells could produce high levels of IFN-gamma which probably inhibit allergen-specific IgE responses. Taken together, our results suggest that allergen-gene transfer is effective in the modulation of allergen-specific IgE responses and may provide a novel therapeutic approach.

The integrated design of mechanical bi-leaflet prosthetic heart valves

A flow model utilizing an irrotational, inviscid algorithm of vortex-ring elements simulating the leaflets and source/sink elements simulating the aortic root coupled with a boundary layer model has been developed to model the internal flow phenomena of bi-leaflet mechanical heart valves implanted in the aortic root. The inviscid representation evaluates the aerodynamic lift, the induced drag, the pitching moment and flow velocity along the leaflet surface thus providing data for evaluating the boundary-layer thickness, the shear stress and flow separation point by the boundary layer theory. Full integration with the geometry enables immediate updates of the flow solution when changes in geometry have been made. It is shown that the effects of the internal flow domain model are necessary in the correct evaluation of lift and drag for subsequent dynamic analysis. The environment presented provides for the ability to produce significant and immediate design changes so that crucial decisions may be made whilst still within the software design loop. New designs are shown along with data for the improved flow model.

Pancreatitis in children--experience with 43 cases

Pancreatitis in children is not common and can be associated with severe morbidity and mortality. We encountered 43 children, ranging in age from 2 to 18 years, with pancreatitis over the past 10 years. The diagnosis of pancreatitis was made in those patients who showed: (1) significant intra-operative pathology or; (2) clinical findings of pancreatic inflammation and laboratory confirmation. More than one third (16 cases) of the cases were due to trauma, other causes included systemic disease (10), structural disease (8), and toxins or drugs (4). Five cases were classified as idiopathic. Most of the patients presented with abdominal pain (95%) and vomiting (56%). Jaundice was found in 7 patients and an abdominal mass in 2. Morbidity included pseudocyst (10), relapse (4), hyperglycaemia (4) and miscellaneous problems. Eight (50%) of the patients with trauma and 6 (86%) of the patients with structural diseases required surgery. Other patients were managed conservatively with bowel rest, gastric decompression, intravenous fluid and total parenteral nutrition. One case had a fatal outcome. All the survivors did well in long term follow up. Relevant literature has been reviewed and the sensitivity of various diagnostic modalities compared and discussed. A lesser known association between pancreatitis and structural anomalies such as choledochal cyst is discussed. To our knowledge, the present review is the first on pancreatitis in Chinese children.

CONCLUSION

Pancreatitis can occur from a wide variety of causes and may result in severe complications. Early diagnosis, close monitoring and aggressive intervention are mandatory to reduce morbidity and mortality.

Immunoprophylaxis of allergen-induced immunoglobulin E synthesis and airway hyperresponsiveness in vivo by genetic immunization

The efficacy of an "allergen-gene immunization" protocol in altering allergic response was examined. Intramuscular injection of rats with a plasmid DNA encoding a house dust mite allergen into the muscle results in its long-term expression and the induction of specific immune responses. Significantly, this approach prevents the induction of immunoglobulin E synthesis, histamine release in bronchoalveolar fluids, and airway hyperresponsiveness in rats challenged with aerosolized allergen. Furthermore, this suppression is persistent and can be transferred into naive rats by CD8+ T cells from gene-immunized rats. These findings suggest that allergen-gene immunization is effective in modulating allergic responses, and may provide a novel therapeutic approach for allergic diseases.

Ricin depresses cardiac function in the rabbit heart

Ricin, at toxic glycoprotein from the castor bean, causes myocardial hemorrhage and a decrease in blood pressure. We studied the effects of ricin on myocardial function in the isolated rabbit heart. Rabbits were given 0.22 micrograms/kg of ricin i.v. and 48 hr later, the heart was isolated and retrogradely perfused through the aorta with Tyrode's solution. A latex balloon was inserted into the left ventricle and isovolumic left ventricular function curves were generated. Left ventricular developed pressure (LVDP), heart rate, coronary artery flow, left ventricular end diastolic pressure, myocardial oxygen consumption, oxygen extraction (a - vO2), and contractility (+dp/dt) were measured over a range of left ventricular volumes. Dose-response curves to isoproterenol (10(-9)-10(-8) M) and phenylephrine (10(-9)-10(-6) M) were also obtained. Compared to the control group, ricin pretreatment markedly decreased ventricular compliance (p < 0.01), diminished maximum left ventricular developed pressure (p < 0.05), and reduced maximal +dp/dt (p < 0.05). Myocardial oxygen consumption, heart rate, electrocardiographic PR, QRS, and QT intervals were not different in control and ricin treatment groups. Ricin did not significantly alter the inotropic or chronotropic responses to isoproterenol and phenylephrine. The results from the binding studies showed that ricin neither reduced beta-adrenergic receptor numbers nor altered the dissociation constant. thus, ricin reduced both systolic (LVDP and +dp/dt) and diastolic (compliance) left ventricular functions, perhaps due to increased vascular permeability, without altering responses to the alpha- and beta-adrenoceptor agonists phenylephrine and isoproterenol.

Acute health hazards of firefighters after fighting a department store fire

The purpose of this study was to evaluate the health hazards of firefighters after fighting a department store fire which lasted for 40 hours. Respiratory symptoms of 168 firefighters were collected and the pulmonary functions of 149 firefighters were measured by spirometer two days after fighting the fire and compared to 32 controls. The principal symptoms manifested by firefighters were burning eyes and mucous membrane irritation. Cross-sectional study of the pulmonary functions showed that FEV1.0, FEV1.0/FVC and the flow rates (MMF, FEF25%, and FEF75%) in smoking exposed firefighters were significantly lower than those in smoking controls. However, only FEV1.0 (%) was significantly lower in nonsmoking exposed firefighters than in nonsmoking controls. Both FVC and FEV1.0 showed a declining trend with the duration of fire fighting. This study provides further evidence that firefighters are exposed to irritants during fighting a fire. Exposure to the combustion products could lead to pulmonary function defects, especially in smoking firefighters.

Xanthogranulomatous cholecystitis: a complication of metallic biliary stent placement

We present a case of 70-year-old female patient who was admitted due to progressive jaundice. Our clinical impression of cholangiocarcinoma (Klatskin tumor), was confirmed by ultrasound, abdominal CT scan, and percutaneous transhepatic cholangiography. Two self-expanding metallic stents were placed in both intrahepatic ducts through a single transhepatic tract. After successful biliary stenting, the jaundice subsided and she was discharged as improved. However, progressive right upper quadrant pain was noted a few days after discharge and persisted for about 5 months, thus the was readmitted. During admission, she was febrile, exhibiting leukocytosis, with clinical signs of impending septic shock. Gallbladder empyema with hilar cholangiocarcinoma were diagnosed. Percutaneous transhepatic cholecystotomy and drainage (PTCCD) was done to alleviate the symptoms and cholecystectomy was performed thereafter. Pathologic report was compatible with xanthogranulomatous cholecystitis. Post-operative recovery was fair at follow-up examination.

Ricin disturbs calcium homeostasis in the rabbit heart

Ricin, a toxic lectin from the castor bean, affects the cardiovascular system. Because calcium is very important in cardiotoxicity and cell intoxication, we studied the effects of ricin pretreatment to rabbits on basal intracellular calcium levels and calcium uptake and release from isolated papillary muscle, microsomes, and mitochondria. An increase in basal intracellular calcium levels was observed. Ricin pretreatment nearly doubled the intracellular-free Ca2+ concentration as measured by fura-2 fluorescence microscopy in isolated myocytes (p = 0.002). Ricin did not alter basal calcium efflux in isolated papillary muscles. However, ricin inhibited the NE-induced calcium efflux (expressed as fractional efflux ratios) in papillary muscles from rabbits receiving the minimum lethal dose of ricin at 25-35 minutes (p = 0.002 and 0.003, respectively). Ricin depressed basal calcium uptake into isolated papillary muscles at 5 minutes (mean +/- SEM, mumol/g wet weight) (control: 3.68 +/- 0.57; ricin: 2.31 +/- 0.28, p = 0.045, n = 6). Ricin pretreatment significantly depressed calcium uptake into microsomes (mean +/- SEM, mumol/g protein) (control: 9.9 +/- 1.9; ricin: 3.1 +/- 1.9, p = 0.025, n = 6). Calcium uptake into mitochondria was increased at the beginning (2 minutes, p = 0.048), but not thereafter. Thus, administration of ricin disturbed calcium homeostasis in the rabbit heart, which may be at least partially responsible for altering cardiac function and myocardial cell death.

Concurrent colon polyp with angiodysplasia causes lower gastrointestinal bleeding: a case report

Angiodysplasia is an important cause of gastrointestinal bleeding which occurs mostly common in the right side of the colon, usually in the elderly but sometimes in younger adults. Herein, a case of rare clinical association-adenomatous colonic polyp with submucosal angiodysplasia in a forty year old man, who had repeated intestinal bleeding, is reported. We think colon polyps inducing intestinal blood loss may be caused by unidentified angiodysplasia. The diagnosis of these lesions is very difficult, so mesenteric angiography is recommended. Although various therapeutic methods were suggested, in patients who have repeated bleeding or are chronic anemics, resection of the involved segment of the bowel is the treatment of choices.

Altered vitamin D metabolism and receptor interaction with the target genes in renal failure: calcitriol receptor interaction with its target gene in renal failure

The genomic action of calcitriol is mediated through the interaction of the calcitriol receptor (VDR) with the vitamin D response elements of the target genes. Although decreased VDR concentration in renal failure could diminish the biological action of calcitriol, recent study indicates that uremic toxins could modify the VDR DNA-binding domain and inhibit the binding of the VDR to the vitamin D response elements. The latter reaction could also account for end-organ resistance in renal failure. The inhibitory action of uremic toxins has been tested in vivo by a method using gene transcription. It was demonstrated that uremic ultrafiltrate blocks calcitriol-induced chloramphenical acetyltransferase reporter constructs containing a synthetic vitamin D response element in JEG-3 cells. Taken together, the findings indicate that uremia could underlie the calcitriol resistance in renal failure. The modification of the VDR may involve Schiff base formation between lysine residues of the VDR DNA-binding domain and reactive aldehydes accumulated in uremia. This suggestion is on the basis of the finding that the VDR and other steroid receptors form Schiff bases with pyridoxal 5'-phosphate and weaken the binding of these receptors to the DNA cellulose.

Inhibition of calcitriol receptor binding to vitamin D response elements by uremic toxins

The genomic action of calcitriol (1,25-dihydroxy-vitamin D3) is mediated through the interaction of the calcitriol receptor (VDR) with vitamin D response elements (VDREs). Although renal failure is associated with resistance to the action of calcitriol, the mechanism of this resistance is not well understood. Therefore, we used the electrophoretic mobility shift assay to compare the ability of VDRs from normal and renal failure rats to bind to the osteocalcin gene VDRE. The results indicate that VDRs from renal failure rats have only half the DNA binding capacity as VDRs from control rats, despite identical calcitriol binding. Furthermore, incubation of normal VDRs with a uremic plasma ultrafiltrate resulted in a loss of > 50% of the binding sites for the osteocalcin VDRE. When VDRs bound to DNA as heterodimers with retinoid X receptors, the inhibitory effect of the uremic ultrafiltrate was due to a specific interaction with the VDR, not retinoid X receptors. In addition, uremic ultrafiltrate blocked calcitriol-induced reporter gene activity in transfected JEG-3 cells. Taken together, the results indicate that an inhibitory effect of a uremic toxin(s) on VDR-VDRE binding could underlie the calcitriol resistance of renal failure.