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Biomedical subjects

D Grant

Publications and source records attributed to D Grant.

At least 127 records · Page 7Linked to original sources
PubMed1995

Improved techniques for kidney transplantation in mice.

Improved microsurgical techniques for kidney transplantation in the mouse are described. Left renal transplantation is performed with end-to-side anastomoses of the donor renal vein to the inferior vena cava and the donor aortic cuff to the aorta. Urinary tract reconstruction is accomplished by suturing the donor ureter with a bladder patch to the recipient bladder. With these modifications, it is possible to achieve success rates as high as 90%. This stable and reproducible model provides a useful tool to study the immunological mechanisms of kidney allograft rejection at the molecular level.

Anastomosis, Surgical↗
PubMed1995

Donor-specific cytotoxicity induced by allogeneic intestinal epithelial cells in a sponge matrix model.

Small intestinal epithelial cells (IEC) constitutively express MHC class II molecules. However, little is known about the role of IEC in intestinal allograft rejection. The present study examined whether IEC can induce the development of cytotoxic T cells in vivo using a sponge matrix model. IEC isolated from ACI (RT1a) rats were injected into polyurethane sponges implanted i.p. in Lewis (RT1(1)) rats. Sponge grafts with ACI splenocytes or Lewis IEC were used as controls. The sponge grafts were removed and sponge-infiltrating cells (SIC) were harvested on post-operative days (POD) 7, 10, and 14. The phenotype of SIC was determined by FACS analysis and the cell-mediated cytotoxicity was measured using a chromium relapse assay. Non-specific inflammatory cells accumulated in the IEC sponge allografts during the first 10 days. By POD 14, however, 61% of SIC were T lymphocytes and 36% expressed cytotoxic T cell marker (OX-8). The cytotoxicity in IEC sponge allografts was detectable on POD 7 and POD 10, and markedly elevated on POD 14. The cytotoxicity induced by allogeneic splenocytes appeared in the sponge grafts on POD 7, peaked on POD 10, and declined thereafter. The allospecific cytotoxicity induced by IEC was dependent on host macrophages as pretreatment of animals with gadolinium, a rare earth metal that inactivates macrophages, abrogated the induction of cytotoxicity. We conclude that: (1) the migration and maturation of cytotoxic T cells can be induced in vivo by IEC and (2) IEC may contribute to the increased severity of intestinal rejection through interaction with macrophages.

Animals↗
PubMed1995

Effect of manganese dipyridoxal diphosphate on liver magnetic resonance imaging and serum bilirubin in rats with removable biliary obstruction.

RATIONALE AND OBJECTIVES: It is known that manganese dipyridoxal diphosphate (Mn-DPDP) causes persisting liver enhancement in cholestatic rats, that free Mn++ plus bilirubin induces intrahepatic cholestasis, and that free Mn++ is released in vivo after Mn-DPDP injection. Hence, there is a concern about potential secondary intrahepatic cholestasis in patients who have biliary obstruction. In this study, we further investigated this issue. METHODS: Removable total biliary obstruction (RTBO) was induced in 12 rats. Six of them (group A) received Mn-DPDP (25 mumol/kg). The others (group B) served as control animals. The data from serial magnetic resonance imaging and serum bilirubin tests were compared. RESULTS: Without Mn-DPDP, a minimal increase of the liver intensity was observed in both groups because of cholestasis. In group A, the intensity of the liver was strongly enhanced with Mn-DPDP but normalized within 48 hr after removal of the obstruction. In both groups, total bilirubin levels increased up to 131.67 mumol/l 2 days after RTBO but rapidly decreased within 4 hr and almost normalized within 24 hr after removal of the obstruction, suggesting a lack of Mn-DPDP influence on the bilirubin level. CONCLUSION: We found that Mn-DPDP did not cause secondary intrahepatic cholestasis. Retained Mn++ is likely eliminated after restoration of bile flow. These results indicate that Mn-DPDP can be used in patients who have obstructive jaundice as long as it is followed by successful bile drainage.

Animals↗
PubMed1995

Gene evolution of epoxide hydrolases and recommended nomenclature.

We have analyzed amino acid sequence relationships among soluble and microsomal epoxide hydrolases, haloacid dehalogenases, and a haloalkane dehalogenase. The amino-terminal residues (1-229) of mammalian soluble epoxide hydrolase are homologous to a haloacid dehalogenase. The carboxy-terminal residues (230-554) of mammalian soluble epoxide hydrolase are homologous to haloalkane dehalogenase, to plant soluble epoxide hydrolase, and to microsomal epoxide hydrolase. The shared identity between the haloacid and haloalkane dehalogenases does not indicate relatedness between these two types of dehalogenases. The amino-terminal and carboxy-terminal homologies of mammalian soluble epoxide hydrolase to the respective dehalogenases suggests that this epoxide hydrolase, but not the soluble epoxide hydrolase of plant or the microsomal epoxide hydrolase, derives from a gene fusion. The homology of microsomal to soluble epoxide hydrolase suggests they derive from a gene duplication, probably of an ancestral bacterial (epoxide) hydrolase gene. Based on homology to haloalkane dehalogenase, the catalytic residues for the soluble and microsomal epoxide hydrolases are predicted. A nomenclature system based on divergent molecular evolution is proposed for these epoxide hydrolases.

Amino Acid Sequence↗
PubMed1995

Pharmacokinetics of a new oral formulation of cyclosporine in liver transplant recipients.

Trough concentrations of cyclosporine can be highly variable because of its poor bioavailability in current oral formulations, Sandimmune (SIM). Neoral (N-SIM) a new microemulsion of cyclosporine is more readily absorbed than SIM in healthy controls. The present study compared the pharmacokinetic profiles of SIM and N-SIM following orthotopic liver transplantation. In 16 patients with partial biliary diversion, 1 week after transplantation, the bioavailability and peak concentration of a single 300 mg dose of N-SIM were greater than SIM by 724% (p = 0.0019) and 800% (p = 0.0001), respectively. In 39 patients who were on stable doses of cyclosporine 1 month after transplantation, the bioavailability of N-SIM was higher than that of SIM under both fasting (+64%, p = 0.001) and fed (+37%, p = 0.004) conditions. Trough concentrations were similar for the two formulations. However, peak concentrations were higher for N-SIM in both fasting (+119%, p = 0.003) and fed (+53%, p = 0.003) patients. Also, time to peak was shorter for N-SIM in both fasting (-21%, p = 0.027) and fed (-59%, p = 0.0001) patients. The correlation between trough concentrations and bioavailability was greater for N-SIM than for SIM in fasted (r = 0.80, p = 0.0001 versus r = 0.75, p = 0.0001) and fed patients (r = 0.65; p = 0.002 versus r = 0.55; p = 0.012). We conclude that the rate of absorption and the bioavailability of N-SIM is significantly and consistently better than SIM and may, therefore, improve the therapeutic index of cyclosporine after liver transplantation.

Administration, Oral↗
PubMed1995

Two-centre evaluation of the Abbott CD3500 blood counter.

The CD3500 blood counter (Abbott Laboratories) is a 33 parameter fully automated blood counter that produces a five part differential count with flagging of leucocyte abnormalities. In this evaluation excellent correlation between CD3500 and Coulter STKR blood counter was found for all red cell and platelet parameters on the 221 samples tested. Studies of carryover, mixing efficiency and precision also gave excellent results. There was a good correlation with manual 400 cell differential counts for neutrophils, lymphocytes, monocytes and eosinophils for the 468 samples compared. Correlation of CD3500 and manual basophil counts was poor. Normal samples stored at 4 degrees C and analysed while cold showed satisfactory stability for WBC, RBC, Hb, MCV and platelets for 48 h and a stable differential for 24 h. Correlation with the differential count produced by the Coulter STKS showed good correlation for neutrophils, lymphocytes, monocytes and eosinophils; correlation with STKS basophils was poor. False positive flagging rate varied between 8.9% (Band and/or IG) and 0.9% (NRBC) depending on the nature of the flag; 5.8% of samples exhibited two or more false positive flags. No significant breakdowns were encountered during the period of the evaluation. The scatterplot displays of laser light scatter produced by the instrument provide an interesting adjunct to conventional morphology.

Blood Cell Count↗
PubMed1995

The use of the hCG stimulation test in the endocrine evaluation of cryptorchidism.

OBJECTIVE: To review retrospectively the value of the human chorionic gonadotrophin (hCG) test in the evaluation of prepubertal boys with bilateral impalpable testes. SUBJECTS AND METHODS: The study comprised 31 boys investigated between 1974 and 1990 at the Hospital for Sick Children, London. All boys had an hCG test consisting of three intramuscular injections of hCG on successive days at a daily dose dependent on their age (< 1 year old, 500 units; 1-10 years, 1000 units; > 10 years, 1500 units). Blood samples were taken before the first dose and 24 h after the last dose and the level of plasma testosterone assessed and expressed as a pre/post ratio. RESULTS: Eight boys had no response to hCG, due to anorchia. One boy had no response to hCG but had bilateral atrophic intra-abdominal testes. Twenty-two boys responded to hCG and had testes whose size was related to the degree of testosterone elevation after this stimulatory test. The hCG test therefore had a positive predictive value of 89% and a negative predictive value of 100%. There was a quantitative difference in testosterone response between 14 boys who had bilateral intra-abdominal testes of 'normal' volume (median pre/post ratio, 11.4) and nine boys who had an otherwise reduced volume of testes (dysplastic or unilateral intra-abdominal) (median pre/post ratio of 4; P = 0.02). CONCLUSION: The hCG test is a valid indicator of the presence of functioning testicular tissue. It is predictive of anorchia and a good response to hCG suggests the presence of testes sufficiently large for orchidopexy.

Child↗
PubMed1995

Old, poor & malnourished.

OBJECTIVE: To monitor the effects of low, fixed incomes on the dietaries and nutritional well-being of elderly people. METHODS: A questionnaire gathered data from a 'high income' sample (HIS) and a 'low income' sample (LIS) on income, eating and shopping patterns and nutritional awareness. A dietary diary provided the data required for a nutritional analysis of the foodstuffs consumed by the sample and inadequacies were identified by comparing nutrient intake to the Dept. of Health's (1991) Dietary Recommended Values (DRVs). RESULTS: The dietaries of the low income sample showed substantial shortfalls from those officially recommended and these are presented as the result, primarily, of income poverty and not the consequence of ignorance or mental decline. The older poor know what healthy eating entails; in most cases, they simply cannot afford and indeed, the dietaries are often inferior to the 'general poor', because of the idiosyncracies of their nutritional requirements. CONCLUSIONS: The inability of the older poor to purchase a healthy dietary cannot be solved merely by health education or budgeting skills. Primarily, they need more money.

Aged↗
PubMed1995

Absorption and excretion of iodixanol after intragastric administration to rats.

Absorption and excretion of iodixanol 320 mg I/ml were investigated in rats after intragastric administration of 2.5 g I/kg b.w. Animals were observed for up to 96 hours after treatment, and blood, urine and feces taken at several time-points throughout the experiment. Concentrations of iodixanol in serum and urine were measured by means of reversed-phase high-performance liquid chromatography. Fecal concentrations of iodixanol, based on iodine measurements, were determined by X-ray fluorescence spectrometry. Serial radiographs were obtained and histopathological examination was performed on selected tissues. The results indicate that less than 1% of the intragastric dose of iodixanol is absorbed from the intestine into the blood stream. No adverse clinical signs were observed, and there were no treatment-related histomorphological findings.

Animals↗
PubMed1995

Tissue reaction follwing intratracheal application of roentgen contrast media in rats.

Contrast media (CM) given orally for roentgen examination of the upper gastrointestinal tract may inadvertently enter the lungs. The present paper describes the local effects on the lungs of rats after a single intratracheal instillation of the nonionic, iso-osmolar, dimer CM iodixanol and iotrolan, and the ionic hyperosmolar, monomeric CM diatrizoate. Hydrochloric acid (HCl) and saline were included as positive and negative controls, respectively. The test compounds were given by intratracheal instillation to anesthetized rats at low dose volumes of 0.5 ml/kg b.w. The animals were killed 6 hours, 24 hours or 7 days after dosing, and the trachea and lungs subjected to histopathological examination. Acute signs of dyspnea were observed in 7 out of 15 animals that received HCl. No clinical signs could be related to treatment with any of the CM. Histomorphological assessment of the respiratory tract did not reveal any CM-related adverse effects, whereas animals treated with HCl showed marked histopathological changes. The results indicate that accidental exposure of the respiratory system to iodixanol, iotrolan or diatrizoate is unlikely to cause any significant tissue damage or lead to respiratory complications.

Animals↗
PubMed1995

Evaluation of a semi-automated reticulocyte counting method using the Coulter STKS-2A blood cell counter.

Reticulocyte counting was assessed on the Coulter STKS-2A automated blood cell counter. Using a two step procedure, blood samples were first incubated with the supravital stain new methylene blue. An acidic reagent was then added to clear the haemoglobin and any stained RNA was preserved within the cell. The cells were then analysed by measurement of volume, conductivity and light scatter (VCS). The results of 123 samples analysed on the STKS-2A were compared with those from a Toa Sysmex R-1000 reticulocyte counter. One hundred and seven samples gave no review flags and reticulocyte counts ranging from 0.5% to 22.8%, resulting in a correlation coefficient of 0.93 for the methods. Between run imprecision studies gave CVs ranging from 5.3% for a reticulocyte count of 8.7% to a CV of 16.3% for a 0.34% count. Stability studies showed insignificant changes over 72 h storage. These findings confirm that VCS technology can be adapted to provide precise and accurate routine reticulocyte analysis.

Automation↗
PubMed1994

Endotoxin in the peripheral blood during acute intestinal allograft rejection.

Intestinal rejection is associated with increased gut permeability and bacterial translocation. The present study examined endotoxin and proinflammatory cytokines in the peripheral circulation during acute intestinal rejection. Heterotopic intestinal transplants were performed using Lewis rats (RT1(1)) as donors and DA rats (RT1a) as recipients. DA rats with intestinal isografts were used as controls. Serum samples were obtained at sacrifice on postoperative days (POD) 7 and 14. Lipopolysaccharide (LPS) was measured using the limulus amoebocyte lysate assay. Interleukin-1 (IL-1) and 6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were measured using bioassays. Large amounts of LPS were detected in the serum of intestinal allograft recipients concurrent with the development of graft rejection. Serum IL-6 and TNF-alpha levels were significantly elevated in the allograft recipients on both POD 7 and 14 when compared to DA isografts (P < 0.05). Serum IL-1 activity was not detected in the allograft or isograft recipients at either of the two time points. Further studies are warranted to determine the role of intraluminal bacteria and their products in the pathophysiology of intestinal allograft rejection.

Acute Disease↗
PubMed1994

Host immune suppression after small bowel/liver transplantation in rats.

Simultaneous liver grafting in the Lewis (RT1)-to-DA (RT1) rat strain combination protects small intestinal grafts from rejection. The present study examined host immune responses after combined small bowel/liver transplantation (SBL) in this model. Orthotopic liver transplantation and heterotopic small intestinal transplantation were performed simultaneously and compared with isolated small bowel allografts (SBA) and isolated small bowel isografts (SBI). All rats were sacrificed on postoperative day (POD) 7 or 14 for immunological and histological studies. The mean time to rejection of the SBA was 6.6 +/- 0.3 days. In contrast, there was no clinical or histological evidence of intestinal rejection in SBL recipients during the 14 days of follow-up. The SBL recipients showed clinical and histological evidence of graft-versus-host disease (GVHD). Lymphocyte proliferation and IL-2 production in response to donor antigens were suppressed after SBL transplantation compared with the SBA or the SBI controls (P < 0.05). Cell-mediated cytotoxicity and lymphocytotoxic antibody production against donor cells were also significantly inhibited in the SBL recipients compared with the SBA control group (P < 0.05). We conclude that SBL transplantation in the Lewis-to DA rat strain combination: (1) suppresses host alloimmune responses, (2) prevents early intestinal rejection, and (3) favors the development of GVHD.

Animals↗
PubMed1994

Are thermolabile splints a source of nosocomial infection?

The aim of this study was to determine whether thermolabile splints used on burned patients became colonized with microbes from the underlying burn or were capable of contaminating burn wounds, and to determine whether the current thermoplastic splint decontamination regimen was effective at removing contaminating bacteria. One hundred and thirty-one standardized swab samples were collected from 28 splints before and after cleaning, and from burn wounds of 10 patients. Qualitative bacterial cultures and identification of isolates were performed. Just over one third of all splints sampled before cleaning were contaminated with bacteria. This compared with over half of the burn wound samples and 17% of the splints sampled after cleaning. Most of the isolates were Gram-positive species including coagulase-negative staphylococci (18), Staphylococcus aureus (12), Bacillus spp. (17) and one isolate of viridans streptococcus. Only five Gram-negative isolates were detected. On only one occasion did the wound and the splint before cleaning have the same organism isolated. Cold disinfection every 24 h was adequate to decontaminate thermolabile splints used on burn patients provided the burn bacterial count was low and care was taken to handle the splints in order to avoid re-contaminating them with health care workers' flora. Thermolabile splints could be a source of burn colonization microbes, but with adequate ward cleaning they were not found to be a problem in our practice.

Burns↗
PubMed1994

Inaccuracy of the 'derived' fibrinogen measurement.

The 'derived' fibrinogen method is commonly used for the measurement of plasma fibrinogen. This method is not a direct quantitation of plasma fibrinogen, but an estimation of the fibrinogen concentration from the clotting curve of the prothrombin time on automated photo-optical coagulometers. An increasing number of laboratories are now routinely using this method to cope with increasing demands for fibrinogen testing. To study the suitability of this method for routine laboratory use a total of 58 samples, 20 healthy normals and 38 from other patient groups were tested by the 'derived' and Clauss fibrinogen methods on the ACL 300R. The results clearly demonstrated that 'derived' fibrinogen assay values were significantly higher than the Clauss measurements. The discrepancy between 'derived' and Clauss fibrinogen levels was greater in certain patient groups, e.g. patients receiving oral anticoagulants, than in normal controls. Some patients with documented hypodysfibrinogenaemia with low fibrinogen levels by Clauss assay gave normal 'derived' fibrinogen values. Although the 'derived' fibrinogen assay is rapid, economical and easily available to laboratories with suitable instruments, this study shows that it lacks standardization and is inaccurate compared with the Clauss assay.

Autoanalysis↗