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Biomedical subjects

G Martin

Publications and source records attributed to G Martin.

At least 163 records · Page 9Linked to original sources
PubMed1996

Alanine metabolism in isolated human kidney tubules--Use of a mathematical model.

To gain insight into the fate of alanine nitrogen and carbon taken up by the human kidney under certain conditions, isolated human kidney cortex tubules were incubated in Krebs-Henseleit medium with L-alanine as substrate. The tubules metabolized alanine at high rates and in a dose-dependent manner. Most of the alanine nitrogen removed was recovered as ammonia and to a lesser extent as glutamate. Glucose, lactate and glutamate were also found to be significant products of alanine carbon metabolism. A simple mathematical model allowing one to calculate flux of alanine carbon through the various metabolic steps involved is proposed and applied to data obtained in experiments in which 5 mM [U-14C]-,[1-14C]-, [2-14C]- and [3-14C]alanine were used as substrates in parallel. About 40% of the alanine carbon removed was recovered as CO2 and oxidation of C1 of alanine accounted for most of the CO2 released from alanine. Calculations reveal that the ATP produced exceeded 3.2-fold the ATP consumed in relation to alanine metabolism. It is concluded that, in human kidney, alanine may serve as an energy supplier and as a precursor of glucose and ammonia.

Adult↗
PubMed1996

Transcription, adipocyte differentiation, and obesity.

Differentiation of adipogenic precursor cells into mature adipocytes is a complex phenomenon, characterized by an ordered expression of adipocyte-specific genes, triggered by a set of interacting transcription factors. The most important transcription factors involved in this process are the gamma form of peroxisome proliferator activated receptors (PPAR gamma) and the various members of the CCAAT enhancer binding proteins (alpha, beta, and delta). In addition to PPAR gamma and these enhancer binding proteins, several other transcription factors, including ADD-1 (SRE-BP), HMGI-C, are involved in regulating this process. Altered activity and/or expression of these transcription factors, will induce the expression of target genes in the differentiating cells, ultimately resulting in the phenotypical characteristics of the adipocytes. It is speculated that modulation of these transcription factors by either pharmacological or dietary manipulations might influence adipocyte differentiation and prove beneficial in the prevention and treatment of obesity.

Adipocytes↗
PubMed1996

Advantages and limitations of the use of isolated kidney tubules in pharmacotoxicology.

Among the cellular models used in in vitro renal pharmacotoxicology, isolated kidney tubules, used as suspensions mainly of proximal tubules, offer important advantages. They can be prepared in large amounts under nonsterile conditions within 1-2 h; thus, it is possible to employ a great number of experimental conditions simultaneously and to obtain rapidly many experimental results. Kidney tubules can be prepared from the kidney of many animal species and also from the human kidney; given the very limited availability of healthy human renal tissue, it is therefore possible to choose the most appropriate species for the study of a particular problem encountered in man. Kidney tubules can be used for screening and prevention of nephrotoxic effects and to identify their mechanisms as well as to study the renal metabolism of xenobiotics. When compared with cultured renal cell, a major advantage of kidney tubules is that they remain differentiated. The main limitations of the use of kidney tubules in pharmacotoxicology are (1) the necessity to prepare them as soon as the renal tissue sample is obtained; (2) their limited viability, which is restricted to 2-3 h; (3) the inability to expose them chronically to a potential nephrotoxic drug; (4) the inability to study transepithelial transport; and (5) the uncertainty in the extrapolation to man of the results obtained using animal kidney tubules. These advantages and limitations of the use of human and animal kidney tubules in pharmacotoxicology are illustrated mainly by the results of experiments performed with valproate, an antiepileptic and moderately hyperammonemic agent. The fact that kidney tubules, unlike cultured renal cells, retain key metabolic properties is also shown to be of the utmost importance in detecting certain nephrotoxic effects.

Animals↗
PubMed1996

The development of the Port-a-Bidet: a portable bidet for people with minimal hand function.

Our Institute has investigated the expressed needs of many severely disabled people. One requirement was for a portable bidet that would fit on a standard toilet, so that they could still have some of the advantages of their automatic washing/drying/flushing toilet when away from their own house. Potential users were consulted, from the specification stage through to final production model testing, to ensure that the desired device was produced. The Port-a-Bidet is a lightweight device, with its own water container, spray unit, pump and power supply. It allows a user with very weak arms to wash themselves with warm water, and a hands-free drying method is explained in the instruction booklet. The whole unit is transported in a discreet carrying bag, and can easily be set up by an unskilled person. The Port-a-Bidet can be controlled by commercially available single switch activators, so that any user can operate it.

Biomedical Engineering↗
PubMed1996

Minocycline prevents the decrease in bone mineral density and trabecular bone in ovariectomized aged rats.

In the current study, we examined the effects of minocycline, on the osteopenia of ovariectomized aged rats. Old female rats were randomly divided into five groups: sham, ovariectomized control and ovariectomized treated with minocycline, 17beta-estradiol, or both agents. Bone samples were collected 8 wk after the treatment. Ovariectomy reduced bone mineral density of the whole femur and at the condylar, distal metaphyseal and head-neck-trochanter regions 10%-19% and the loss of bone density was prevented by treatment with minocycline or 17beta-estradiol. Histomorphometric analysis of distal femur showed ovariectomy reduced the trabecular bone area, the trabecular bone number, trabecular bone thickness and increased the trabecular bone separation. The microanatomic structure of trabecular bone also showed that the number of nodes, node to node, cortical to node, node to free end was reduced by ovariectomy. Treatment with minocycline attenuated the effect of ovariectomy on trabecular bone in aged animals. In contrast, cortical bone was not affected by ovariectomy or minocycline treatment. The effect of minocycline on bone turnover was also examined. Minocycline increased osteoid surface, mineralizing surface, mineral apposition rate, bone formation rate and reduced eroded surface. We have therefore concluded that the modest increase in bone mineral density and the improvement in the trabecular bone status noted in minocycline treated ovariectomized aged rats is likely due to an increase in bone formation coupled with a decrease in bone resorption.

Absorptiometry, Photon↗
PubMed1996

Mediastinal mass following chemotherapy in patients with Ewing sarcoma and osteosarcoma.

Thymic hyperplasia following combination chemotherapy for malignant disease is very uncommon in adolescents and adults. Our experience includes a thymic enlargement noted on the sequential computed tomography (CT) in three patients who were disease-free after chemotherapy for Ewing sarcoma (2) and osteosarcoma (1). The development of an anterior mediastinal mass after successful chemotherapy does not always imply relapse of malignant disease. To prevent inappropriate treatment, the possibility of benign aetiology must be considered.

Adolescent↗
PubMed1996

[Secondary internal osteosynthesis after external fixation for recent or old open fracture of the lower limb].

PURPOSE: The purpose of our study is to analyse the indications, results and limits of secondary internal fixation after external fixation for open fracture of the lower limb. MATERIAL: Our series covered 21 patients treated between 1991 and 1994. There were 17 men and 4 women. Tibia was affected 17 times and femur 5 times (one bifocal fracture). In Gustilo's classification, we had 1 case of type 1, 12 of type II and 8 of type III. METHODS: We used 15 times the FESSA External Fixator and 6 times a monotube external fixator in emergency. We have done secondary 11 intra medullary nailing and 11 patients were treated by plating (one patient had both) 13 patients had a bone graft (cortico-cancellous graft). In the first group of patients (10 cases), the initial treatment gave us good results for both skin and bone healing. The external fixation was replaced by an internal one in order to accelerate bone consolidation and to allow an early weight-bearing. Removal of the external fixation was made at an average of 4 months postoperative. In the Second group (11 cases) the internal fixation was proposed because of an insufficiency of the external fixation leading to complications as: non union, mal union and bone defects. External fixation was removed in a mean time of 8 months. Internal fixation was completed by local bone autograft. RESULTS: 17 patients have been reviewed. Consolidation occurred with an average of 6 months after internal fixation 1 to 24 months. We had no deep infection but only 2 superficial ones. DISCUSSION: We chose 2 types of indication, and we called them programmed and for necessity. The first group of 10 patients whose stain was moderate and whose initial setting up had permitted a perfect anatomic reduction with a rapid wound healing. Internal fixation was performed after a short duration of external fixator. An early weight bearing was allowed so that the functional recovery could be obtained quickly. The second group is represented by patients whose internal fixation was done for non union, malunion or bone defect. In such a case autogenous cancellous graft was used to fill the defect.

Adolescent↗
PubMed1996

Substance abuse treatment for Ontario residents in the United States.

In Canada, individuals experiencing problems related to their alcohol and drug use receive treatment and rehabilitative care through services provided primarily through the publicly funded health and social service system. During the past decade, however, an increasing number of Canadians have received treatment for substance abuse at facilities located in the United States, with most of the cost for this treatment borne by the various provincial health insurance plans. This paper provides a comprehensive analysis of the Ontario experience of treatment for substance abuse in the United States. First, the policy and planning context for the use of American treatment programs by Ontario residents and the rationale for recent changes to the reimbursement guidelines for such out-of-country treatment is reviewed. Secondly, the major trends in utilization of American programs over the past decade will be described and comparisons drawn to trends in the development of Ontario's own treatment system. This information has been used to help guide the development of treatment services in Ontario. In addition, the data serve as a baseline to measure the impact of various policy and program initiatives recently introduced in Ontario to reduce the utilization of treatment resources based in the United States.

Adolescent↗
PubMed1996

[Immunization with potential Salmonella enteritidis mutants-- 2. Investigations on the attenuation and immunogenicity for mice and young hens].

Adenine-amino acid auxotrophic Salmonella Enteritidis double mutants were investigated for their in vivo stability, attenuation und immunogenicity using NMRI-mice and SPF-chicks. All mutants used were stable in vivo and attenuated. Two mutants were selected for immunization experiments in chickens according to their protective ability after a single intraperitoneal immunization in NMRI-mice using a homologous and heterologous challenge. After two oral immunizations and homologous oral challenge with the S. Enteritidis wild type strain 6403Nalr, a significant difference (p < 0.01) was demonstrated between the mean caecal bacterial counts of immunized and control chicks. Examination of liver samples revealed a significantly lower degree of colonization of internal organs (p < 0.01) in immunized birds. There was no evidence of cross protection against S. Typhimurium using S. Enteritidis mutants.

Animals↗
PubMed1996

[Immunization with potential Salmonella enteritidis mutants--1. Production and in vitro characterization].

Production and in vitro characterization of potential vaccine strains are the first steps leading to an efficient Salmonella Enteritidis oral live vaccine for homologous immunization of poultry. The paper presents the results of the production of adenine-amino acid auxotrophic mutants using N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. The mutant strains were characterized using the following properties: auxotrophy, stability of mutation, reversion rate, generation time, metabolic properties, serotype, motility, plasmid content, phage type, SDS-PAGE patterns, as well as cell culture adhesion and invasion. Ten S. Enteritidis double auxotrophic mutants were obtained which are stable auxotrophically and where the risk of reversion was minimal. All strains were found to be plasmid-free. 5 mutants were selected for further investigations concerning their attenuation and immunological value.

Animals↗
PubMed1996

[Inhibition phenomena between Salmonella strains--a new aspect of salmonella infection control in poultry].

Freshly hatched chickens show a very high susceptibility to Salmonella infections and control measures are therefore frequently focused on the period shortly after hatching. Experimental investigations using one strain against itself, differentiated by different antibiotic resistance markers, have shown that colonisation with Salmonella prevents the establishment of subsequently inoculated challenge organisms in the chicken gut. The inhibition effect lasts for several days and is detectable even when a challenge dose of 10(8) organisms is used. It is dependent of the breed of bird. Chickens colonised with Salmonella shed a subsequently inoculated challenge strain with significant lower numbers for several weeks than do non colonised control birds. The phenomenon is strain specific but not serovarspecific as has been shown in investigations using different strains of the same and other serovars for colonisation and challenge. The phenomenon shows a large variability between strains. Using other Enterobacteriaceae strains comparable inhibition against Salmonella was not observed. One important topic for further investigation is the capability of Salmonella live vaccines given orally to establish a protection effect, based on the inhibition phenomenon in the first few days of live, developing into a long-lasting immunity when birds reach immunological maturity.

Animals↗
PubMed1995

A single intraseptal injection of nerve growth factor facilitates radial maze performance following damage to the medial septum in rats.

Rats were trained on a radial maze and then given electrolytic lesions of the MS followed by a single intraseptal injection of 5 micrograms of NGF. Three days later they were re-tested on the maze. They were also post-operatively tested for hyperemotionality. MS lesions severely impaired performance on the radial maze and produced increased emotionality. MS lesions also produced a general decrease in hippocampal high affinity choline transport and acetylcholinesterase staining, which was not affected by NGF administration. NGF treatment ameliorated the behavioral deficit in the radial maze but had no effect on the hyperemotionality. In order to determine whether the NGF was working to restore previously learned spatial abilities, the type of learning strategy used by the animals was also assessed. NGF treatment did not restore previously learned spatial strategies but facilitated recovery of alternative learning strategies. The reduction in cognitive deficit was also paralleled by reduced ventricular enlargement in the NGF treated rats. The present results suggest that a single injection of NGF can produce a long-lasting improvement on a cognitive task and reduce some of the injury-induced, secondary reactive changes that occur following electrolytic MS lesions.

Analysis of Variance↗