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Biomedical subjects

L Martin

Publications and source records attributed to L Martin.

At least 451 records · Page 25Linked to original sources
PubMed1987

Regulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity in mouse uterine epithelial cells.

The regulation of 3-hydroxy-3-methylglutaryl-CoA reductase was studied in mouse uterine epithelium. The enzyme was rapidly inactivated during incubation with ATP/Mg2+ in vitro, and could be re-activated by incubation with partially purified rat liver phosphoprotein phosphatase. Enzyme activity was rapidly inhibited by mevalonate injection in vivo to approx. 30% of control. The percentage of total enzyme active in vivo was measured by inclusion of NaF in the isolation buffers. The percentage of enzyme active in vivo 18 h after stimulation by oestrogens remained at approx. 25% after inhibition of activity by mevalonate injection, cholesterol feeding or progesterone pretreatment. However, 9 h after oestrogen stimulation, cholesterol feeding inhibited enzyme activity to 57% of control, 94% of which was in the active form. We conclude that, although all components for a reversible phosphorylative regulation of 3-hydroxy-3-methylglutaryl-CoA reductase activity are present in uterine epithelial cells, a role in the rapid changes in epithelial enzyme activity has not been demonstrated.

Animals↗
PubMed1987

In vitro and in vivo characterization of an impervious polyester arterial prosthesis: the Gelseal Triaxial graft.

Over the years, textile polyester arterial prostheses have acquired an excellent reputation for easy handling and good healing characteristics. Until recently, the main drawback in using them was the need for preclotting. This, however, is no longer true. Nonporous polyester grafts which have been coated with an impervious bioerodible layer during manufacture are now commercially available. The Gelseal Triaxial prosthesis is one of this new generation of grafts. It is manufactured by impregnating a Triaxial prosthesis with a gelatin coating. An in vivo and in vitro evaluation of this new device has found that its water permeability is almost zero. It has good handling and conformability characteristics, and its bursting strength is slightly greater than that of the uncoated prosthesis due, no doubt, to the presence of the gel. The rates of degradation of the gelatin coating have proven to be rapid under both in vitro and in vivo conditions. In fact, only a few traces of the gel were found remaining on the graft after 2 wk in the canine thoracic aorta. In addition, this study has demonstrated that the use of a bioerodible gelatin coating, with its ability to promote cellular regeneration, is a feasible approach with which to achieve earlier and more complete biological healing.

Animals↗
PubMed1987

Linogliride fumarate, representing a new class of oral hypoglycemic agent for diabetes.

This study presents the first multiday therapy trial of linogliride fumarate, a representative of a new class of oral hypoglycemic agents. Linogliride demonstrated a significant hypoglycemic activity in 26 patients with non-insulin-dependent diabetes mellitus receiving 1 week of therapy. In a dose range of 150 to 400 mg b.i.d., fasting glucose levels fell from 237 +/- 52 mg to 199 +/- 59 mg by day 7 (P less than 0.01). Eight-hour glucose AUCs fell from 2121 +/- 617 mg/dl/8 hr baseline to 1781 +/- 631 mg/dl/8 hr on day 7 of treatment (P less than 0.01). This was associated with a significant increase in insulin AUC from 380 +/- 327 to 610 +/- 417 on day 7 (P less than 0.01). Thus its initial action appears to be by an insulin secretagogue mechanism. No patient had any major adverse effect. This initial study indicates that linogliride fumarate is an effective hypoglycemic agent that significantly lowers fasting and postprandial glucose levels with short-term use. Linogliride fumarate represents a new group of hypoglycemic agents that may be shown to have therapeutic utility.

Administration, Oral↗
PubMed1987

Albumin-coated polyester arterial prostheses: is xenogenic albumin safe?

This paper adds a new dimension to the series of studies concerned with the development of an albumin-coated polyester vascular prosthesis by addressing the question of the origin of the albumin. Previous experiments in dogs have used canine albumin-coated polyester arterial grafts. This study evaluated the biocompatibility of xenogenic material by implanting in dogs prostheses coated with bovine albumin and cross-linked with glutaraldehyde. Two series of albuminated grafts, one gamma radiation sterilized, the other ethylene oxide sterilized, as well as a preclotted control series were undertaken. The origin of the albumin did not appear to be significant. In fact, the healing pattern of the xenogenic albumin coated grafts was identical to that found previously with isogenic albumin. Nor did the method of sterilization produce significantly different pathological results. However, a slower rate of healing with the coated grafts compared to the preclotted controls did appear to be related to the slow rate of albumin erosion and the potentially cytotoxic effect of the glutaraldehyde cross-linking agent.

Albumins↗
PubMed1987

[Pseudarthrosis of the scaphoid bone. Experiences in 240 cases].

The results after treatment of 197 non-union of scaphoid fractures are reported. The operative technique of Matti-Russe, called also Russe I, has proved successful in cases in which the fracture is located in the middle or distal third of the scaphoid or where there is a viable small proximal fragment. Bone healing depends more on the age of the pseudarthrosis than on the age of the patient. In 86% of 83 cases the technique of Russe I was successful and in this group the period between accident and treatment was no longer than two years. After a period of more than four years after the accident the success rate is only 54%. The combination of the technique of Russe I with styloidectomy of the radius diminishes the number of good results. The operative technique known as Russe II assumes a good blood supply of the distal fragment of the scaphoid. In 15 cases, after resection of the necrotic small proximal fragment of the scaphoid, a fungiform bonegraft from the iliac crest was placed in the cavity and the success rate was 80%. The findings after palliative treatment of 43 non-unions of the scaphoid are based on subjective criticisms by the patients. The denervation of the wrist and the wrist arthrodesis were done in 28 cases. After resection of the necrotic proximal fragment, a tendon interposition arthroplasty was performed in nine cases, and in six cases a prosthesis for the proximal part of the scaphoid was implanted.

Bone Transplantation↗
PubMed1987

Tandem scanning reflected light microscopy of primate enamel.

Studies of the cross sectional packing arrangements of primate enamel prisms have been used in a number of recent studies in attempts to determine their taxonomic utility. Credibility of the results has been greatly influenced by the methods employed to examine enamel prism packing patterns and also by the limited sampling. We report here the use of a technique for the non destructive examination, in depth, of enamel prism packing patterns in modern and fossil primate teeth which has considerable advantages over any others so far used, and the preliminary results of a survey of enamel structural diversity in the Order Primates. The phylogenetic implications of these findings are also discussed. A novel microscope, the Tandem Scanning Reflected Light Microscope (TSM) has been used. This instrument has allowed these data to be obtained non destructively which has permitted the inclusion of rare fossil primates in this survey. The technique has many advantages relating to the interpretation of the results as the specimens are not etched or otherwise prepared. Primates exhibit all three major prism packing arrangements known for recent mammals. The distribution of these permits the recognition of haplorhine from strepsirhine primates and also cercopithecoid monkeys from other catarrhines.

Animals↗
PubMed1987

Comparison of assays for growth hormone using monoclonal or polyclonal antibodies for diagnosis of growth disorders.

Current diagnostic standards for growth hormone deficiency were derived from measurement of growth hormone using polyclonal antibody assays. Recently, however, immunoassays using monoclonal antibodies to growth hormone have been commercially introduced. This study compares growth hormone levels obtained with two new monoclonal assays with levels obtained with a standard polyclonal assay. In 20 patients, the polyclonal assay (National Pituitary Agency) measured a mean growth hormone concentration of 14.0 +/- 10 (SD) ng/dl compared with monoclonal assay 1 (Hybritech) measurement of 10.4 +/- 7.2 ng/dl (P less than 0.01) and monoclonal 2 (Wellcome Co.) measurement of 18.9 +/- 9.8 ng/dl (P less than 0.01). The Hybritech monoclonal assay measured lower growth hormone levels than the polyclonal assay in all 20 patients. The Wellcome assay measured higher growth hormone levels than the polyclonal assay in 17 of 20 patients. There is not complete agreement between polyclonal and monoclonal antibody growth hormone assays in their measurement of plasma growth hormone levels. Clinicians using the new monoclonal antibody growth hormone assays will need to carefully develop separate diagnostic criteria for growth hormone deficiency that takes into account the disparity between the polyclonal assays that were used in the development of the current diagnostic standards and the new monoclonal antibody assays.

Adolescent↗
PubMed1986

Rheumatic diseases in an Inuit population.

Prevalence and incidence rates for rheumatic diseases were found to be minimal among the Inuit people in the Keewatin District of the Northwest Territories, Canada. Patient identification was achieved by a review of medical records. All identified patients were interviewed and examined by a participating rheumatologist. Among women, the prevalence of rheumatoid arthritis, adjusted for age of the Manitoba population, was 1,822 per 100,000 and was comparable with that observed in other populations; no cases of rheumatoid arthritis in men were confirmed. The age-adjusted prevalence of osteoarthritis, 1,219 per 100,000 in men and 2,144 per 100,000 in women, was apparently low. A moderately high incidence of Reiter's syndrome, 24.9 per 100,000, was found. The findings in children suggested a high frequency of seronegative spondylarthropathies (yearly incidence 60.1 per 100,000), although the adjusted yearly incidence for juvenile rheumatoid arthritis also appeared to be high, 23.6 per 100,000. The frequencies of HLA antigens in patient groups were compared with those found in 19 patients with musculoskeletal complaints but no rheumatic disease. Both HLA-B27 and HLA-DR4 appeared to be common in these controls, 36.8% and 63.2%, respectively. Nevertheless, there was a higher frequency of HLA-B27 in patients with seronegative spondylarthropathies (87%) than in controls (P = 0.001). Because of the small numbers of patients who had rheumatoid arthritis, no associations with HLA were made for this condition. Although the findings suggest differences in the distribution of rheumatic diseases compared with those found in other populations, more complete studies are required to confirm these observations.

Adult↗
PubMed1986

New polyester arterial prostheses from Great Britain: an in vitro and in vivo evaluation.

Two models of knitted velour polyester prostheses have been developed in Great Britain, i.e. the VP1200K and the VP50K Triaxial. The evaluation of these new devices in vitro and in vivo in dogs has demonstrated that, while the first model has similar surgical, mechanical and healing characteristics in the short term to other commercial knitted velour prostheses, the second model has lower water permeability and superior strength and dimensional stability. On the basis of these results, clinical investigations can be undertaken.

Animals↗
PubMed1986

[Consumption coagulopathy and meningioma].

A twenty year old man died after coagulation disorders following neurosurgery. Disseminated intravascular coagulation and fibrinolysis occurring after neurosurgery of brain tumours are discussed.

Adult↗
PubMed1986

Four cases of traumatic optic nerve blindness in the horse.

Traumatic optic nerve atrophy is characterised clinically by a unilateral or bilateral sudden onset of blindness. Dilated, fixed pupils and a lack of a menace reflex are the only abnormalities noted soon after the trauma. Within three to four weeks the optic disc becomes paler and the retinal vasculature is markedly decreased. The pathological lesion is a rupture of the nerve axons from stretching forces produced by the posterior movement of the brain against the fixed canalicular portion of the optic nerves. Medical therapy has not been successful.

Animals↗
PubMed1986

Chemically fixed human umbilical cord vein grafts as arterial substitutes: potential and limits.

In spite of reported successes, synthetic fabric grafts and microporous and plain synthetic conduits have proven unsuitable for aorto-coronary bypasses and showed weaknesses below the knee. Readily available and uniform diameter vascular substitutes with biological and mechanical properties comparable to human vessels would be of paramount interest. Following reported successes with chemically fixed human umbilical veins (HUV), we have attempted to develop smaller diameter blood conduits and have improved the currently prevalent techniques of fixation, preparation and storage to generate more convenient surgical products. In vitro assessment of the processed HUV demonstrated that the HUV can be easily processed to make an arterial substitute that can be preserved either in a liquid medium or as a dry product. However, the in vivo implantations in dogs led to disappointing results for liquid-preserved or albuminated veins. Critical-point dried grafts gave better results, unfortunately they do not heal and they can only degrade after implantation.

Animals↗
PubMed1985

A compound arterial prosthesis: the importance of the sterilization procedure on the healing and stability of albuminated polyester grafts.

In response to the demand for a vascular prosthesis which achieves reliable haemostasis without preclotting, a new compound albumin/polyester prosthesis has been developed. In order to optimize the sterilization procedures for this device, two series of implantations in the thoracic aorta of dogs were undertaken to compare the effects of ethylene oxide (EtO) and gamma-radiation. Preclotted polyester prostheses were implanted in two additional control series. Pathological analysis of the explanted grafts indicated that gamma-radiation is to be preferred over EtO because it results in faster rates of healing. While the albumin coating delayed the thrombotic response and fibrinolytic activity, the extent of healing of the radiation sterilized graft was equivalent to that achieved by preclotted polyester prostheses in the medium and long term. Measurements of the strength and dimensional changes of the graft demonstrated that, in addition to reducing the risks of acute thrombosis and postoperative haemorrhage, the albumin coating improves the dimensional stability of the knitted structure.

Albumins↗