Biomedical subjects

D Grant

Publications and source records attributed to D Grant.

At least 91 records · Page 5Linked to original sources

PubMed1997

Comparison of manganese biodistribution and MR contrast enhancement in rats after intravenous injection of MnDPDP and MnCl2.

PURPOSE: To compare the time course of the MR enhancing properties and biodistribution of manganese (Mn) in rats given i.v. Mn dipyridoxyl diphosphate (MnDPDP) or Mn chloride (MnCl2). MATERIAL AND METHODS: Twenty-four adult rats were injected i.v. with 5 mumol/kg MnDPDP or MnCl2, or with 0.5 ml/kg saline. High resolution T1-weighted MR imaging was performed during early (10 min), mid (2 h) and late (24 h) phases after injection. Mn concentrations in major organs were measured by using an ICP-AES technique, and correlated with MR findings. RESULTS: Variable degrees of signal enhancement of major organs observed in MR images corresponded with the amount of Mn uptake after injection of MnDPDP or MnCl2. A prominently lower cardiac, pancreatic and hepatic uptake of Mn was seen at 10 min in rats injected with MnDPDP compared with those given MnCl2 and this was reflected in a difference in signal intensity (SI) in the MR images. At 2 h, the Mn content and SI in the major organs were similar with both MnDPDP and MnCl2. An overall Mn clearance was achieved at 24 h without any important organ retention, with kidney excretion of Mn seen only with MnDPDP. CONCLUSION: With both MnDPDP and MnCl2, the Mn uptake correlates with the SI enhancement in tissues. The reduced initial cardiac uptake of Mn after MnDPDP treatment compared to MnCl2 may account for the favourable cardiovascular safety of the contrast agent. These data contribute to an understanding of SI enhancement by MnDPDP, and are consistent with other studies showing that at a dose of 5 mumol/kg, MnDPDP can be safely used as a potent MR organ-specific contrast agent.

Animals↗

PubMed1997

NMR relaxation studies with MnDPDP.

PURPOSE: Our studies were designed to compare the efficacy of mangafodipir trisodium (MnDPDP, Teslascan) as a tissue-specific MR agent with that of manganese chloride (MnCl2), to compare the efficacy of different doses and rates of administration of MnDPDP, and to collect the data needed for predicting optimum pulse sequences. MATERIAL AND METHODS: The dose response for the relaxation rates R1 and R2 at 0.47 T, and the manganese (Mn) concentrations in rat liver and in the liver, pancreas, heart and adrenals of pigs was determined for both MnDPDP and MnCl2 administered i.v. Computer simulations were carried out to model the effects of different tissue Mn concentrations and TR on signal intensities and contrast-to-noise ratios. RESULTS: In rat liver and pig organs both compounds produced a positive dose-response in R1 and tissue Mn concentration, and only small or no response in R2. The Mn concentration in rat liver was positively correlated with R1, regardless of the form in which Mn was given, or the rate of administration. Optimal imaging parameters are therefore expected to be different pre- and post-MnDPDP administration. CONCLUSION: The added cardiovascular safety of MnDPDP compared with MnCl2 does not result in loss of efficacy in increasing RI at the intended clinical dose of 5 mumol/kg MnDPDP. The changes in R2 were too small to affect T2-weighted images. The data give the basis for choosing the appropriate pulse sequences for MnDPDP-enhanced MR imaging.

Animals↗

PubMed1997

Tissue distribution and general safety of MnDPDP in male beagle dogs, with or without total common bile duct obstruction.

PURPOSE: Evaluation of the tissue distribution of manganese (Mn) and general safety in normal and cholestatic male beagle dogs after i.v. administration of mangafodipir trisodium (MnDPDP, Teslascan). MATERIAL AND METHODS: Male beagle dogs, with or without surgical obstruction of the common bile duct, received a single i.v. bolus injection of saline (control), or MnDPDP at doses of 10 or 50 mumol/kg b.w. and were sacrificed 1 or 7 days after treatment. Toxicity was assessed and tissue concentrations of Mn were measured. RESULTS: Increased tissue Mn concentrations were found in all dogs treated with MnDPDP and were greatest in those with biliary obstruction. Although Mn concentrations decreased with time in most tissues in each of the treated groups, this was not the case for the brain and adrenal glands in dogs with total biliary obstruction in which further increases in Mn concentrations were seen at the later time point. This suggested a re-distribution of Mn from the major body depots such as the liver. There were no effects of MnDPDP on clinical signs/behaviour, organ weights, histomorphology or clinical biochemistry. CONCLUSION: These findings indicate that a single clinical dose of 5 mumol/kg MnDPDP is likely to be well tolerated in patients with cholestasis.

Animals↗

PubMed1997

The reproductive toxicology of intravenously administered MnDPDP in the rat and rabbit.

PURPOSE: The reproductive toxicology of mangafodipir trisodium (MnDPDP, Teslascan), a new hepatobiliary MR contrast agent, was evaluated in rats and rabbits. MATERIAL AND METHODS: Male and female fertility and post-natal development were examined in rats after repeated i.v. injections of MnDPDP. The developmental toxicity in rats was investigated after repeated daily i.v. injections during organogenesis with MnDPDP, MnCl2, or DPDP, as well as with MnCl2 administered orally. The developmental toxicity of i.v. injected MnDPDP was also investigated in rabbits. RESULTS: MnDPDP (100 mumol/kg) had no adverse effects on rat fertility. However, both MnDPDP (10-40 mumol/kg) and MnCl2 (30 mumol/kg) caused skeletal abnormalities in the rat, but not in the rabbit given 20 mumol MnDPDP/kg. Maternal treatment of rats with MnDPDP (40 mumol/kg) reduced survival and body weights of neonates, and adversely affected their functional, but not physical development. No skeletal abnormalities were seen in the rat after i.v. administered DPDP (40 mumol/kg) or MnCl2 (6 mumol/kg), or after MnCl2 (400 mumol/kg) given by oral gavage. Maternal toxicity was not seen in rats or rabbits given these doses. CONCLUSION: MnDPDP caused skeletal abnormalities in foetal rats, but not rabbits, and had no effects on rat fertility. Manganese appears to be the causative agent for inducing bone abnormalities in the rat.

Abnormalities, Drug-Induced↗

PubMed1997

General toxicology of MnDPDP.

PURPOSE: To investigate the general toxicology of mangafodipir trisodium (MnDPDP, Teslascan). MATERIAL AND METHODS: Studies were performed in accordance with standard methods and in compliance with regulations current at the time of conduct. RESULTS: Single-dose studies in rodents and dogs showed that MnDPDP was tolerated at doses of approximately 2000 mumol/kg, approximately 400 times a single imaging dose of 5 mumol/kg. The single dose tolerance of MnDPDP was approximately 10 times greater than MnCl2. A good safety profile of MnDPDP was also shown in repeat-dose studies (3 weeks), in which the no-observed-adverse-effect level for the rat, monkey and dog was 116, 29 and 10 mumol/kg, respectively. The local tolerance studies indicated that no adverse local tissue reactions are likely to occur after i.v. injection. Other studies indicate that accidental spillage of MnDPDP onto the skin is not expected to lead to significant systemic exposure, or to local irritation or hypersensitivity. MnDPDP was not genotoxic in a battery of several different tests. CONCLUSION: MnDPDP was shown to have a good safety profile suitable as an hepatobiliary MR contrast agent for i.v. administration.

Animals↗

PubMed1997

Small bowel transplantation in children.

Small bowel transplantation has become a life-saving procedure for selected adults and children with intestinal failure who are intolerant to parental nutrition. There are few pediatric data available on the results of this procedure. In this article we review the background of intestinal transplantation, present the results from the University of Western Ontario in London, Ontario and the University of Miami in Miami, Florida, and discuss some future directions. The majority of successful transplants are fully functional, and these children are able to assume a normal diet.

Child↗

PubMed1997

Immigration patterns, social support, and adaptation among Korean immigrant women and Korean American women.

There are little empirical data available on the mental health and social functioning of Korean American Women (both native U.S. born and foreign Korean-born U.S. residents, inclusive). State-of-the-art research used to inform social work practice is exploratory descriptive. With the goal of contributing to the social work knowledge base regarding this understudied population, this article uses an emic understanding and approach to examine immigration patterns, social support networks, and issues around adaptation experienced by Korean American women. Issues examined include gender role disruption, limited use of social services, and evidence of depressive symptoms in Korean American women and subsequent risk of substance abuse, suicide, battering, loss of employment, deficits in parenting, and mental health problems. Focus on these areas of functioning suggests the need for development of culturally competent community, family, individual, and organizational-level intervention strategies.

Acculturation↗

PubMed1996

Pattern of liver, kidney, heart, and intestine allograft rejection in different mouse strain combinations.

With advances in microsurgery and molecular biology, the mouse model for organ transplantation has become increasingly popular. However, knowledge about these models is limited, as only a small number of centers have experience with murine models. In this study, we compared the rejection pattern after liver, kidney, heart, and small bowel transplantation in the three different mouse strain combinations: (1) C57BL/6 (H2b)-->BALB/c (H2d), (2) BALB/c (H2d)-->CBA (H2k), and (3) C57BL/6-->C3H/HeN (H2k). Our study demonstrated that mouse allograft survival varies depending on the organ graft and on the donor-recipient strain combinations. The majority of liver allografts were spontaneously accepted despite complete MHC disparity. A mixed pattern of acute rejection and acceptance occurred in kidney recipients depending on the donor-recipient strain combination. All the heart grafts developed rejection and all the intestinal grafts were rapidly rejected with no spontaneous acceptance. The criteria for rejection, the potential applications, and the limitations of each model are discussed. The models described in this article provide a number of useful choices for organ transplantation research.

Animals↗

PubMed1996

Influence of macrophage depletion on bacterial translocation and rejection in small bowel transplantation.

Rejection and sepsis can be intimately related following small bowel transplantation when rejection compromises normal intestinal barrier mechanisms and bacterial translocation results. Macrophages play a role in controlling the egress of intestinal luminal bacteria--and they have also been implicated in allograft rejection. In this study, the role of macrophages in rejection and bacterial translocation was evaluated by depleting macrophages in donors and/or recipients of rat small bowel allografts with injection of liposome-encapsulated dichloromethylene diphosphonate (CL2MDP). In preliminary studies, we demonstrated that a single intraperitoneal injection of liposome-encapsulated CL2MDP (350 mg/kg) depleted ED2-positive macrophages by > 90% in the liver mesenteric lymph nodes and proximal and distal small bowel, and by approximately 50% in the spleen. ED1-positive macrophages were depleted by > 90% in the liver and by approximately 50% at the other sites. ED3-positive macrophages were completely depleted. Dendritic cells were > 90% depleted in the spleen and mesenteric lymph nodes, but were not depleted in the small bowel. Macrophage depletion in the donor resulted in increased translocation of bacteria to the peritoneal cavity (P = 0.03) if recipient macrophages were present. With histopathologic analysis, a significantly milder rejection with less arteritis was seen in the allografts of the recipient macrophage-depleted group compared with nondepleted controls (P = 0.045). This suggests that recipient macrophages play an important role in rejection. With macrophage depletion in both the donor and the recipient, graft survival was prolonged significantly (13.2 +/- 1.9 days) compared with non-macrophage-depleted controls (9.2 +/- 1.3 days) (P = 0.003). These studies suggest that strategies targeting recipient macrophages may be useful in controlling small bowel allograft rejection without increasing bacterial translocation.

Animals↗

PubMed1996

Oligodeoxynucleotides containing C-7 propyne analogs of 7-deaza-2'-deoxyguanosine and 7-deaza-2'-deoxyadenosine.

The synthesis, hybridization properties and antisense activities of oligodeoxynucleotides (ODNs) containing 7-(1-propynyl)-7-deaza-2'-deoxyguanosine (pdG) and 7-(1-propynyl)-7-deaza-2'-deoxyadenosine (pdA) are described. The suitably protected nucleosides were synthesized and incorporated into ODNs. Thermal denaturation (Tm) of these ODNs hybridized to RNA demonstrates an increased stability relative to 7-unsubstituted deazapurine and unmodified ODN controls. Antisense inhibition by these ODNs was determined in a controlled microinjection assay and the results demonstrate that an ODN containing pdG is approximately 6 times more active than the unmodified ODN. 7-Propyne-7-deaza-2'-deoxyguanosine is a promising lead analog for the development of antisense ODNs with increased potency.

Base Sequence↗

PubMed1996

Current results of intestinal transplantation. The International Intestinal Transplant Registry.

BACKGROUND: Intestinal transplantation is an alternative to total parenteral nutrition (TPN) for the treatment of chronic intestinal failure. To determine the current status of small-bowel transplantation, we have reviewed the world experience since 1985. METHODS: We built up an international registry by asking twenty-five intestinal transplantation programmes to submit standard data on their cases operated on between 1985 and June, 1995. FINDINGS: One centre (two transplantations) did not use our report form, and these cases were excluded. The remaining twenty-four programmes did 180 transplantations in 170 patients. Two-thirds of the recipients were children. The main indication (64 percent) was short-gut syndrome, another 13 percent had a tumour. Of the grafts, 38 percent were small-bowel with or without colon, 46 percent were intestine plus liver, and 16 percent were multivisceral. Graft/patients' survival (percent) at 1 and 3 years under cyclosporin immunosuppression was, respectively: 17/57 and 11/50 for small bowel only; 44/44 and 28/28 for intestine plus liver; and 41/41 and 41/41 for multiviscera. The corresponding figures under tacrolimus were: 65/83 and 29/47; 64/66 and 38/40; and 51/59 and 37/43. 78 percent of the 86 survivors had stopped TPN and resumed oral nutrition. INTERPRETATION: Our approach cannot give data on long-term outcome. The short-term results of intestinal transplantation are similar to those of lung grafting. We conclude that small-bowel transplantation has become a life-saving option for patients who cannot be maintained on TPN and for those who require massive abdominal evisceration for locally aggressive tumours.

Adolescent↗

PubMed1996

An analysis of late deaths after liver transplantation.

Late deaths (after more than 1 year) after liver transplantation were analyzed in a series of 464 consecutive patients who received liver grafts between 1982 and 1993. Recipients who survived the first posttransplant year (n = 365) had actuarial 5- and 10-year survival rates of 92% and 84%, respectively. Thirty-five patients died between 1.1 and 7.6 years after transplantation (mean, 3.2 +/- 1.9 years). The most common causes of death were related to immunosuppression (40%), namely, chronic rejection, opportunistic infection, and lymphoma. The second most common causes of death were related to the primary disease for which liver transplantation was performed (34.3%), mainly recurrence of hepatobiliary malignancy and hepatitis B. Eight patients (22.9%) died of unrelated and unpredicted causes, most commonly of cardiovascular disease. Although the survival of liver recipients who live beyond the first posttransplant year is excellent, control of rejection and the consequences of chronic immunosuppression are continual threats. Modification of immunosuppression may help in decreasing the mortality of long-term survivors. In addition, better selection of recipients and effective adjuvant therapies (antiviral and antineoplastic) are needed in patients in whom the primary liver disease is notorious for recurrence.

Adolescent↗

PubMed1996

Small bowel transplantation. A life-saving option for selected patients with intestinal failure.

Thirty-seven patients were listed for small bowel transplantation; 16 were transplanted and 15 died while waiting for a donor. Cyclosporine (N = 6) or tacrolimus (N = 10) were used for immune suppression. Graft rejection rates were lower in the combined liver/small bowel grafts than the isolated intestinal transplants (1/7 vs 5/7; P < 0.01) All of the cyclosporine group have died; the median survival was 25.7 months with two patients living more than five years. The tacrolimus group had fewer infections and a shorter hospital stay. All but two are alive with a median survival of 13 months. Seven of eight long-term survivors are off intravenous feedings. We conclude that small bowel transplantation is a life-saving option for patients with intestinal failure who cannot be maintained on total parenteral nutrition.

Adolescent↗

PubMed1996

Potent and selective inhibition of gene expression by an antisense heptanucleotide.

Factors that govern the specificity of an antisense oligonucleotide (ON) for its target RNA include accessibility of the targeted RNA to ON binding, stability of ON/RNA complexes in cells, and susceptibility of the ON/RNA complex to RNase H cleavage. ON specificity is generally proposed to be dependent on its length. To date, virtually all previous antisense experiments have used 12-25 nt-long ONs. We explored the antisense activity and specificity of short (7 and 8 nt) ONs modified with C-5 propyne pyrimidines and phosphorothioate internucleotide linkages. Gene-selective, mismatch sensitive, and RNase H-dependent inhibition was observed for a heptanucleotide ON. We demonstrated that the flanking sequences of the target RNA are a major determinant of specificity. The use of shorter ONs as antisense agents has the distinct advantage of simplified synthesis. These results may lead to a general, cost-effective solution to the development of antisense ONs as therapeutic agents.

Animals↗

PubMed1996