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Biomedical subjects

P Martin

Publications and source records attributed to P Martin.

At least 361 records · Page 20Linked to original sources
PubMed1998

Cerebral 1H MR spectroscopy and neuropsychologic status of patients with hepatic encephalopathy.

OBJECTIVE: Our objective was to assess the metabolite levels (myo-inositol [ml], choline [Cho], creatine [Cr], glutamate or glutamine [Glx], and N-acetyl-L-aspartate [NAA]) visible on 1H MR spectroscopy in patients with subclinical and mild hepatic encephalopathy before and after liver transplantation and to correlate these data with the results of neuropsychiatric tests and related clinical findings. SUBJECTS AND METHODS: A stimulated-echo sequence was used to localize a single voxel in the parietal region. Seventeen patients and 13 healthy volunteers were investigated. Nine of the 17 patients also were investigated after liver transplantation. A battery of neuropsychologic tests also was administered to patients to assess frontal, memory, and motor functions. RESULTS: Before liver transplantation, significant reductions in mI:Cr (51%) and Cho:Cr (11%) and a significant increase in Glx:Cr (20%) were observed in patients compared with the respective ratios in healthy subjects. Patients also were significantly impaired on neuropsychologic tests measuring frontal and motor performance, but not memory. Impairment on the frontal index showed a significant correlation with mI:Cr levels; likewise, performance on the motor index showed a significant correlation with serum ammonia levels before transplantation. MR spectroscopy after liver transplantation showed changes in the metabolite ratios compared with the pretransplantation status. Even though the Glx:Cr ratios decreased after transplantation, the mI:Cr ratio remained lower than those of healthy subjects. CONCLUSION: The relationship of changes in the metabolite ratios recorded from a voxel in the posteromedial parietal lobe to the neuropsychologic findings before and after liver transplantation is a major finding.

Adult↗
PubMed1998

[Endoscopic therapy of cholangiolithiasis by percutaneous approach. Percutaneous gallstone therapy].

PATIENTS AND METHODS: In a retrospective study, the results of percutaneous transhepatic therapy of bile duct stones under cholangioscopic control (PTCS) were evaluated in 32 patients in which a endoscopic retrograde stone removal was impossible or failed. RESULTS: Previous gastric surgery was the most common reason for choosing the percutaneous route (22 cases). Five patients had biliodigestive anastomosis, two pyloric obstructions, and in three patients the retrograde stone removal failed. Complete stone removal was obtained after 3 to 11 (median 5) percutaneous procedures in all cases, in 28 patients by electrohydraulic lithotripsy, and in the remaining 5 cases by mechanical extraction alone. There was no complication due to cholangioscopy and lithotripsy themselves. Two cases had major complications which needed laparotomy (4%, one case had capsular bleeding from the liver, another one had catheter perforation of the duodenum). In addition, three cases (7%) had minor complications which required no therapy during the percutaneous fistula procedure. Two elderly multimorbid patients (4%) died during hospitalisation after successful stone removal not related to the performed procedure. CONCLUSION: The percutaneous transhepatic cholangioscopy (PTCS) and lithotripsy are highly effective techniques for endoscopic treatment of bile duct stones. Because of an increased rate of complications during the fistula procedures, both methods should be restricted to cases with difficult anatomic situation and high risk of surgery.

Adult↗
PubMed1998

Invasive hyphomycotic rhinitis in a cat due to Metarhizium anisopliae.

Invasive mycotic rhinitis was diagnosed in a cat with a 4-month history of stertor, nasal discharge and subcutaneous swelling of the nasal bridge. Histology demonstrated fungal hyphae in representative biopsies of the nasal cavity and subcutaneous mass. Mycological culture demonstrated a pure growth of Metarhizium anisopliae var. anisopliae. The infection was treated with orally administered itraconazole. This is the first well documented case of infection by M. anisopliae in a mammalian host.

Animals↗
PubMed1997

Differential splicing of pre-messenger RNA produces multiple forms of mature caprine alpha(s1)-casein.

The identity of multiple forms of caprine alpha(s1)-casein in variants A, B, and C has been determined by structural characterisation using mass spectrometry, automated Edman degradation and peptide mapping. Mature goat alpha(s1)-casein exists as a mixture of at least four molecular species which differ in peptide chain length. The main component corresponds to the 199-residues form already described. The other three, in lesser amounts, were shorter forms of alpha(s1)-casein and differed for the deleted peptides 141-148, as shown previously for ovine alpha(s1)-casein, peptide 110-117, or Gln78. Analysis of alpha(s1)-casein mRNA from milk somatic cells demonstrated that these forms originated from skipping events at the level of exon 13 (codifying for peptide 110-117) and 16 (codifying for peptide 141-148) and from the presence of a cryptic splice site within exon 11 (whose first CAG triplet encodes Gln78) during primary transcript processing. The finding of these splicing abnormalities in the three common variants A, B, and C suggests that this is a general feature of alpha(s1)-casein in goat. A further source of heterogeneity of caprine alpha(s1)-casein was identified in the discrete phosphorylation of seryl residues. Eight serine residues (at positions 44, 46, 64 to 68 and 75) are fully phosphorylated (except in variant A because of the replacement Glu77-->Gln which prevents phosphorylation of Ser75). Conversely, Ser115 and Ser41 are phosphorylated only to about 50% and 20%, respectively. Ser12, although located in a consensus triplet, is never phosphorylated, similarly to the ovine alpha(s1)-casein variants. These results confirm that there are stabilised mechanisms of simultaneous synthesis of alpha(s1)-casein at different length and of post-translational modification in both caprine and ovine species.

Alternative Splicing↗
PubMed1997

MK-801-induced hyperlocomotion: differential effects of M100907, SDZ PSD 958 and raclopride.

The influence of three selective monoamine receptor antagonists on spontaneous locomotion and on the hyperlocomotion induced by the un-competitive N-methyl-D-aspartate (NMDA) receptor antagonist [+]-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]-cyclohepten-5,10-imine hydrogen maleate (MK-801; dizocilpine) was investigated. The selective and potent 5-hydroxytryptamine (5-HT)2A receptor antagonist R(+)-alpha(2,3-dimethoxyphenyl)-1-[2(4-fluorophenyl)ethyl)]-4-piperidine -methanol (MDL100,907; M100907) displayed a clear-cut selectivity for reduction of MK-801-induced as compared to spontaneous locomotion, in that the former was dose-dependently (0.001, 0.01, 0.1 mg/kg i.p.) blocked and even totally abolished by the highest dose, while the latter was only modestly affected. Even at high doses of M100907 (up to 9 mg/kg i.p.), spontaneous locomotion was not reduced below 40% of control. The selective dopamine D1 receptor antagonist (-)-[4aR, 10 aR]-1,2,3,4,4a,5,10,10a-octahydro-4-(4-chloro-2-methyl-phenyl)-1-methyl- benzo[g]quinoxaline-6-ol (SDZ PSD 958; 0.017, 0.15, 1.35 mg/kg i.p.) decreased both spontaneous and MK-801-induced locomotion with a slight preference for the latter; spontaneous locomotion was dose-dependently diminished to approx. 10% of controls (at 8 mg/kg i.p.). The dopamine D2 receptor antagonist raclopride ([(-)-(S)-3,5-dichloro-N-((1-ethyl-2-pyrrolidinyl) methyl)-6-methoxy-salicylamide tartrate]; 0.11, 0.33, 1.0 mg/kg i.p.) reduced both MK-801-induced and spontaneous locomotion to a similar extent. An orthogonal matrix experimental design, and multiple regression, were used to evaluate the effects of several combinations of different doses of the 5-HT2A receptor antagonist and the dopamine D1 receptor antagonist. No synergistic actions on reduction of spontaneous or MK-801-induced locomotion were detected between M100907 and SDZ PSD 958. If the hyperlocomotion elicited by acutely administered MK-801 is a valid model of at least some aspects of schizophrenia, these results indicate that the 5-HT2A receptor antagonist M100907 will have efficacy in treating this condition. The lack of effect on spontaneous locomotion, suggests that M100907, compared to dopamine receptor antagonists, will be less prone to induce psychomotor side-effects. Ongoing clinical studies will hopefully give the answers in the near future.

Animals↗
PubMed1997

Cyclosporine or cyclosporine plus methylprednisolone for prophylaxis of graft-versus-host disease: a prospective, randomized trial.

Patients with a lymphohematopoietic malignancy considered to be at high risk for posttransplant relapse were enrolled in a study to compare the use of cyclosporine (CSP) as a single agent with a combination of methylprednisolone (MP) and CSP for graft-versus-host disease (GVHD) prophylaxis after marrow transplantation from an HLA-identical sibling donor. Sixty patients were randomized to receive CSP only and 62 were randomized to receive CSP plus MP. Daily CSP was started on day -1 (5 mg/kg/d intravenously) and administered at gradually reduced doses until day 180. MP was started on day 7 at 0.5 mg/kg/d, increased to 1.0 mg/kg/d on day 15, started on a taper schedule on day 29, and discontinued on day 72. All 104 evaluable patients (surviving > or =28 days) had sustained engraftment. The incidence rates of grades II-IV acute GVHD were 73% and 60% for patients receiving CSP and CSP plus MP, respectively (P = .01). No difference was seen for grades III-IV GVHD. However, chronic GVHD occurred somewhat more frequently in patients receiving CSP plus MP (44%) than in patients receiving only CSP (21%; P = .02). The incidence of de novo chronic GVHD was marginally higher in patients receiving CSP plus MP (P = .08). No significant differences in the risk of infections were observed. There was a suggestion that the risk of relapse was lower in patients receiving CSP plus MP (P = .10) and, although the overall survival in the two groups was not different (P = .44), there was a slight advantage in favor of CSP plus MP-treated patients for relapse-free survival (P = .07). These results suggest that prophylactic MP, when combined with CSP, has only limited efficacy in acute GVHD prevention and may increase the probability of chronic GVHD.

Adolescent↗
PubMed1997

Effects of chronic diazepam treatment on pre- and postsynaptic 5-HT1A receptors in the rat brain.

Biochemical and electrophysiological approaches were used to assess possible changes in 5-HT1A receptors in the rat brain after long-term treatment with an anxiolytic benzodiazepine. Rats were treated with diazepam (2 mg/kg i.p. daily) during 14 days and then untreated for 1 day (protocol A) or 5 days (protocol C) until they were killed for in vitro investigations on 5-HT1A receptors. In addition, other rats (protocol B) received the same 14-day treatment with diazepam, followed by 1 mg/kg of the drug on days 15 and 16, and 0.5 mg/kg on days 17 and 18, and were killed 24 h after the last injection. In vitro binding and quantitative autoradiographic experiments with [3H]8-hydroxy-2-(di-n-propylamino)tetralin ([3H]8-OH-DPAT) showed that the characteristics of 5-HT1A receptor binding sites in the hippocampus and the dorsal raphe nucleus were not significantly altered by the administration of diazepam under the treatment protocols A, B and C. Furthermore, in vitro electrophysiological recordings of serotoninergic neurons in the dorsal raphe nucleus of brain stem slices revealed no modification in the sensitivity of somatodendritic 5-HT1A autoreceptors in rats treated with diazepam according to the protocols A and B. However, under the conditions of protocol C, the potency of 8-OH-DPAT to depress the firing rate of serotoninergic neurons was significantly enhanced, as expected of a hypersensitivity of somatodendritic 5-HT1A autoreceptors. These data support the hypothesis that some functional changes in these receptors could occur during benzodiazepine withdrawal. However, they do not support the idea of a reduced anxiolytic efficacy of 5-HT1A receptor agonists as a result of prior treatment with a benzodiazepine.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1997

Wound healing--aiming for perfect skin regeneration.

The healing of an adult skin wound is a complex process requiring the collaborative efforts of many different tissues and cell lineages. The behavior of each of the contributing cell types during the phases of proliferation, migration, matrix synthesis, and contraction, as well as the growth factor and matrix signals present at a wound site, are now roughly understood. Details of how these signals control wound cell activities are beginning to emerge, and studies of healing in embryos have begun to show how the normal adult repair process might be readjusted to make it less like patching up and more like regeneration.

Animals↗
PubMed1997

Genetic heterogeneity in sporadic colorectal adenomas.

The majority of colorectal cancers develop from adenomatous polyps under the influence of factors that are still poorly understood. Tumourigenesis is generally considered a multistep process in which multiple genetic alterations occur, eventually reflected in abnormalities of the cellular DNA content. Macroscopical features such as tumour size and tumour architecture (tubular, tubulovillous, or villous) are correlated wit the chance of malignancy in the lesion. Grade of dysplasia can be considered an indicator for the level of progression of the adenoma towards invasive carcinoma. These characteristics were correlated with the presence or absence of K-ras mutations and the DNA ploidy in a prospective study performed on 46 large sporadic colorectal adenomas resected by endoscopy. DNA ploidy and K-ras mutations were analysed in two samples taken at distant sites in the adenomas. Aneuploidy was present in 12 adenomas (26 per cent) and K-ras mutations occurred in 26 (57 per cent). A highly significant correlation was found between aneuploidy and adenoma size, architecture, and grade of dysplasia. The presence of K-ras mutations was significantly correlated only with the size of the adenomas. The proportion of adenomas with aneuploidy and/or a K-ras mutation increased when two samples were analysed instead of one. This observation suggests that the prevalence of genetic mutations and of aneuploidy is probably underestimated, as generally only one sample is investigated. No correlation was observed between K-ras mutations and ploidy. This study demonstrates the presence of genetic heterogeneity in colorectal adenomas and supports the notion that K-ras mutation is an early event, while aneuploidy is a late event in the adenoma-carcinoma sequence.

Adenoma↗
PubMed1997

Detection of somatic mutations in the mitochondrial DNA control region of colorectal and gastric tumors by heteroduplex and single-strand conformation analysis.

Each entire hypervariable region of the mitochondrial DNA control region was screened for mutations from paired normal and tumor DNA corresponding to a group of 21 patients (13 colorectal and 8 gastric adenocarcinomas) using both heteroduplex analysis and single-strand conformation analysis. These two mutation scanning strategies allowed the identification of sequence alterations in 3/13 (23%) colorectal tumors and in 3/8 (37%) gastric tumors. Heteroduplex analysis showed the heteroplasmic state of the majority of these tumor mutations. Sequence analysis revealed two A:T/G:C transitions (nucleotide positions: 16241 and 16166) in hypervariable region 1 (HV1) and two C:G/T:A transitions (nucleotide positions: 76 and 312), one A:T/G:C transition (nucleotide position: 93), a 1-basepair C:G deletion (nucleotide position: 309), and a 2-base-pair CC:GG insertion (nucleotide position: 309) in the HV 2 region. A considerable proportion of these mutations was found in homopolymeric regions which are highly polymorphic among humans. Different mechanisms (clonal expansion, increased oxidative damage, and nuclear mutator mutations) were suggested to explain the increased mitochondrial DNA mutation rate observed in cancer.

Adenocarcinoma↗
PubMed1997

Aplastic anemia complicating orthotopic liver transplantation.

The clinical characteristics and outcome of posttransplantation aplastic anemia (AA) were determined in 12 of 1,736 patients (0.007%) undergoing orthotopic liver transplantation (OLT) that were afflicted with AA. None of the affected patients had a history of hematologic disease. Median patient age was 53 years (range, 2-61 years); 10 of the affected patients were men, and 2 were women. The etiologies of AA included non-A, non-B, non-C fulminant hepatic failure (FHF) (3 patients), graft-versus-host disease (4 patients), Parvovirus-induced (1 patient), and idiopathic (4 patients). The median duration between OLT and the onset of AA was 12 days (range, 11-14 days) in the 3 patients undergoing OLT for FHF; in contrast, AA developed in the other 9 patients at 37 days (range, 27-51 days) after OLT. Eleven patients were treated with reduction of their cyclosporine or tacrolimus dosage, granulocyte colony-stimulating factor, anti-thymocyte globulin, and Solumedrol. Two of the 3 patients developing AA following OLT for FHF achieved hematologic recovery 21 and 92 days after diagnosis. In contrast, all 9 non-FHF patients developing AA after OLT died, 5 due to infectious complications and 4 following intracranial bleeding. AA is an unusual complication of OLT. In the setting of FHF, it affects young males in the early posttransplantation period, and, when infectious complications can be avoided, remission and stable allograft function can be anticipated. However, in the non-FHF patient, AA occurs in older individuals later in the posttransplantation period and has a uniformly poor outcome.

Adult↗
PubMed1997

Minimal criteria for placement of adults on the liver transplant waiting list: a report of a national conference organized by the American Society of Transplant Physicians and the American Association for the Study of Liver Diseases.

This report summarizes a recent meeting cosponsored by the American Society of Transplant Physicians and the American Association for the Study of Liver Diseases to formulate minimal criteria by which patients with severe liver disease will be placed on the waiting list for liver transplantation. The participants agreed that only patients in immediate need of liver transplantation should be placed on the waiting list. Patients should not be placed in anticipation of some future need for such therapy. It was agreed that minimal criteria could assist but not replace the clinical judgment of the transplant professionals at individual centers. The criteria will be summarized below for adult patients with acute or chronic liver disease. The most important non-disease-specific criterion for placement on the transplant waiting list was an estimated 90% chance of surviving 1 year. This translated into a Child-Pugh score of > or = 7 for patients with cirrhosis which places the patient in Child-Pugh class B or C. Cirrhotic patients who have experienced gastrointestinal bleeding caused by portal hypertension or a single episode of spontaneous bacterial peritonitis would meet the minimal criteria irrespective of their Child-Pugh score. There were disease-specific criteria also. These include a sole minimal criterion for patients with fulminant hepatic failure regardless of etiology of the onset of stage 2 hepatic encephalopathy. A requirement for 6 months abstinence from alcohol before placement on the transplant waiting list was considered appropriate for most patients with alcoholic liver disease. Exceptional cases could get access to the waiting list through a regional review process. Chronic cholestatic diseases present difficulties because of a different natural history than that of chronic hepatocellular diseases. The use of specific risk scores for primary biliary cirrhosis and primary sclerosing cholangitis will likely replace Childs-Pugh classification as the scoring systems become refined. Minimal criteria for any patient with a primary hepatocellular cancer would admit any patient with a tumor confined to the liver irrespective of size or number of tumors, after careful investigation had failed to show spread to lymph nodes, the portal vein, or distant organs. Unusual or rare indications for liver transplantation, including Budd-Chiari syndrome, Wilson's disease, and other hereditary disorders, were also discussed. Finally, it was agreed that there should be no absolute contraindications to placement of patients on the liver transplant waiting list. These criteria should be open to regular review to accommodate advances in the field.

Adult↗