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Biomedical subjects

M Martens

Publications and source records attributed to M Martens.

At least 55 records · Page 3Linked to original sources
PubMed1989

Response of lower genital tract flora to external pelvic irradiation.

Endocervical and vaginal cultures were obtained every week from patients undergoing external pelvic irradiation for gynecologic malignancy. Gram-positive aerobes accounted for 52 to 56% of isolates, gram-negative aerobes accounted for 15 to 16%, and anaerobes accounted for 29 to 32% of all isolates prior to therapy. No significant changes occurred during or after completion of radiation for the group. In individual patients, however, over 50% of organisms found on initial culture were no longer present on completion of external therapy.

Bacteria↗
PubMed1989

Patella alta in patellofemoral instability.

In a retrospective study of 90 realignment procedures for patellar instability, a high percentage of patella alta was diagnosed based upon the preoperative radiographs: 53% or 48 knees. The LP-LT index, described by Insall and Salvati, averaged 0.80 for this group of patients. Post-operative measurements of this index showed a definite correction of the craniocaudal position of the patella, with a mean increase of 0.10 (0.80 to 0.90). In evaluating the severity of the eliciting trauma, it is suggested that the alta position makes the patella more prone to instability: only 14.5% of the alta knees (n = 48) sustained a significant trauma versus 28.5% in the non-alta population (n = 42). The altaposition, however, had no influence on the final outcome, (at a mean follow-up time of 57 months), after a latero-medial realignment procedure, using a proximal or a combined proximal and distal procedure.

Adolescent↗
PubMed1989

Ticarcillin/clavulanic acid versus clindamycin and gentamicin in the treatment of post-cesarean endometritis following antibiotic prophylaxis.

One hundred fifty-two women who received cefazolin prophylaxis and subsequently developed postpartum endometritis were randomized to treatment with either ticarcillin/clavulanic acid (75) or clindamycin-gentamicin (77). Bacteria isolated from the endometrium were predominantly facultative anaerobic bacteria. The ratio of facultative anaerobes to obligate anaerobes was 3:1. Nineteen percent of the women were bacteremic, with mycoplasma the organism most frequently isolated from venous blood specimens. Cure rates were similar for both groups: ticarcillin/clavulanic acid 85% and clindamycin-gentamicin 81%. The advantages of ticarcillin/clavulanic acid are an increased spectrum of activity against beta-lactamase-producing bacteria, less toxicity, and lower cost.

Adult↗
PubMed1989

Biomechanical characteristics of iliac crest bone in elderly women according to osteoarthritis grade at the hand joints.

Postmortem iliac crest trabecular bone specimens were tested in compression to determine their mechanical characteristics. Trabecular bone volume and width were evaluated by histomorphometry and radiographic grading of osteoarthritis (OA) of hand joints was also done. Patients were divided into 2 groups: no or low grade OA (Group 1) and manifest OA Grades II-IV (Group 2). From the 27 specimens tested (women 56-80 years old), 17 were in Group 1 and 10 in Group 2. Significant differences in stiffness (E), compressive strength, trabecular bone volume and trabecular width between the 2 groups were found. In the group with manifest OA, bone was significantly stiffer, had a significantly increased compressive strength value, a significantly higher trabecular bone volume and trabecular width, compared to the group with no or low OA grade. Significant correlations were found between elastic modulus and trabecular bone volume and width, and also between compressive strength and trabecular bone volume and width. Our findings support the hypothesis that the primary defect in OA is not in the articular cartilage but in the subchondral bone and that primary OA is part of a more general bone disease.

Aged↗
PubMed1988

Potentiation of glucocorticoid-induced lysis in refractory and resistant leukemia cells by inhibitors of ADP-ribosylation.

Meta-iodo-benzylguanidine (MIBG; 3 x 10(-5) M), a novel inhibitor of mono(ADP-ribosylation)-and the general ribosylation inhibitor nicotinamide (NA; 5-20 mM) both stimulated the glucocorticoid-mediated lysis of sensitive L1210 leukemia cells and even induced susceptibility in various human and murine lines refractory or resistant to dexamethasone (DEX). Potentiation and induction of DEX-sensitivity by ADP-ribosylation inhibitors was accompanied by an increase in saturable 3H-DEX binding sites and by a 2-3 fold increase in the affinity of intracellular receptors for hormone binding. Moreover, the ribosylation inhibitors converted the glucocorticoid antagonist RU-486 into a potent agonist for cytolysis of L1210 cells. We conclude that the cytolytic action of glucocorticoid hormones in leukemic cells is negatively controlled by (mono)ADP-ribosylation of receptor proteins.

3-Iodobenzylguanidine↗
PubMed1988

The distortive mechanism for the activation of complement component C1 supported by studies with a monoclonal antibody against the "arms" of C1q.

A mouse monoclonal antibody (IgG1 isotype) against human C1q (MAb 130) is presented that activates C1 in serum through its antigen-binding sites at an optimal molar ratio of 3 MAbs:1 C1q. The antibody does not inhibit binding of C1q to IgG. Experiments with pepsin- and collagenase-digested C1q showed that MAb 130 binds to the fibril-like strands (arms) of C1q, close to the globular heads. Bivalency of MAb 130 was a requirement for C1-activation, but not for binding to C1q. Increasing the segmental flexibility of the intact antibody by reduction and alkylation destroyed its capacity to activate C1. A MAb against the globular heads of C1q completely inhibited C1-activation by aggregated IgG (AHG), but did not prevent activation by MAb 130. C1, reconstituted by adding C1q-stalks that lack the globular heads to C1q-depleted serum was not activated by AHG, whereas activation by MAb 130 was not affected. Activation of serum-C1 by AHG and MAb 130 was inhibited by addition of excess purified C1-inhibitor in a comparable and dose-dependent manner. Sucrose-gradient analysis indicated a predominance of stable complexes of a single C1q-molecule with three MAbs at the optimal activating ratio. When isolated and added to C1q-depleted serum, these complexes activated C1 efficiently. A mechanism for activation by MAb 130 is proposed that supports the "distortive" model of C1-activation.

Antibodies, Monoclonal↗
PubMed1988

Ticarcillin disodium/clavulanate potassium versus clindamycin/gentamicin in the treatment of postpartum endometritis.

Ticarcillin disodium/clavulanate potassium was compared to clindamycin/gentamicin in the treatment of post-cesarean-section endometritis in 133 evaluable patients. All patients received three 1-g doses of cefazolin for prophylaxis. There was no statistically significant difference in the cure rates between the ticarcillin disodium/clavulanate potassium group (84%) and the clindamycin/gentamicin group (81%). Bacteremia occurred in 21% of the patients, with Mycoplasma the most frequent isolate. Ticarcillin disodium/clavulanate potassium was found to be as efficacious as clindamycin/gentamicin in the treatment of postpartum endometritis.

Cefazolin↗
PubMed1987

Dorsal defect of the patella: concept of its origin and relationship with bipartite and multipartite patella.

In a series of 2286 single radiographic examinations of the knee in 1985, 6 dorsal defects of the patella (DDP) were detected. The diagnosis was made if a round lucent lesion of the dorsal superolateral surface of the patella was found abutting against articular cartilage. In four of our patients, an association with a multipartite patella (MP) was found. Biopsy of one lesion showed dense connective tissue and areas of bone necrosis. In one patient, the pattern of reossification of the lesion could be demonstrated. Our observations provide further evidence that the DDP is a stress-induced anomaly of ossification rather than a post-traumatic subarticular cyst of the patella, a diagnosis sometimes suggested by the clinical context. The initial lesion is probably a traction lesion at the insertion of the vastus lateralis muscle rather than ulceration of articular cartilage. We suggest a possible relationship between dysfunction of the quadriceps mechanism, patellar subluxation, and the genesis of the DDP.

Adolescent↗
PubMed1987

Proposal of limit concentrations for skin irritation within the context of a new EEC directive on the classification and labeling of preparations.

In this study, solvents belonging to different chemical families were tested for their irritating properties to the skin. The irritating potential of a chemical is expressed as its concentration in a nonirritant diluent beyond which irritation of the skin may be expected in the sense of EEC Directive 79/831/EEC. The substances were applied onto the shaved skin of rabbits by means of a modified Finn chamber for 4 hr. Afterward the exposure chamber was removed and the skin cleaned. Reading of erythema and edema was performed according to the scale of Draize at 1, 24, 48, and 72 hr after the removal of the patch. On the basis of the readings obtained the different dilutions of the organic solvents tested were classified as irritant or not according to the interpretation rules laid down in EEC Directive 83/467/EEC. On the basis of the structure-activity relationships found within each chemical family the irritation potential of the other members of the family could be derived via interpolation.

Alcohols↗
PubMed1986

Mechanical behaviour of femoral bones in bending loading.

A series of 33 human femoral bones have been subjected to a four point bending test at high strain rates. Two different failure modes were recognized. A Y shaped fracture at the middle region induced by a pure bending moment yielded a zone of non-linearity at the load vs deformation curve and a higher bending force, more deformation of the structure and higher strain energy to fracture compared with the less frequently occurring oblique fracture at the distal third of the structure resulting in a failure without a 'plastic' portion at the load-deformation curve. Estimated values of bending modulus and maximum bending moment based upon a simple uniform beam model showed high correlation coefficients with the experimentally determined values. Scanning electron microscopic examination of the Y fracture showed distortion and void formation of the material at the structural level. This could explain the extensive non-elastic deformation prior to failure.

Aged↗
PubMed1986

Shyness, group dependence and self-concept: attributes of the imaginary audience.

The imaginary audience of 328 early and late adolescents was studied from the viewpoint of providing educators and clinicians with insight into its attributes--those which both facilitate and hinder youths' development. Early adolescents (about 14 or 15 years of age) displayed a greater awareness of an imaginary audience which probably contributed to their observed, elevated group dependence. Unexpectedly, the shyness of adolescents highly sensitive to an imaginary audience increased with age, possibly because they are unwilling to provide themselves with the social experiences necessary for decentering. Likewise, those highly sensitive to an imaginary audience projected low self-concepts and thus imply that their audience is relatively critical; thus, they probably validate a self-fulfilling prophecy, oblivious to a possible contradictory external reality. The anticipated fact that females appeared to be less socially bold and more group dependent than males might account, in part, for females' greater responsiveness to an imaginary audience. It is suggested that educators and clinicians encourage youth to validate social hypotheses in order to promote the dissolution of the imaginary audience, especially of those who are shy and display self-deprecatory tendencies.

Adolescent↗
PubMed1985

Transchondral talar dome fracture.

Transchondral talar dome fractures have been reported to be a cause of persisting ankle pain and a cause of delayed return to sports, due to late diagnosis and thereby often neglected treatment. Especially in athletes, these lesions--if untreated--may result in a chronic disability for sports activity. Clinical findings, the importance of new diagnostic aids, and differential treatment methods are presented, based on 39 patients with 41 osteochondral fractures seen between 1976 and 1983, with an average follow-up of 5.1 years. Twenty-two patients were treated conservatively, with good results in 12 cases and moderate results in four, six patients were lost to follow-up. Seventeen patients underwent surgery. Results were good in nine and moderate in three. Four operated patients were graded with poor results, due to limitations in their sports activity or work; one patient was lost to follow-up.

Adolescent↗
PubMed1984

In vivo metal-ion release from porous titanium-fiber material.

Dense and porous Ti, Ti-alloy, and stainless steel specimens were implanted in canine trabecular bone. After 6 and 12 months the specimens were retrieved together with bone tissue immediately adjacent. The trace metal content in the tissue samples was determined using neutron activation analysis, differential pulse polarography, graphite furnace atomic-absorption spectrophotometry, electron microprobe analysis, and laser microprobe analysis. The results are discussed in view of (i) the release of Ti ions, which is larger for porous than for bulk specimens, (ii) the various artifacts arising in electron microprobe (EMP) and laser microprobe mass analysis (LAMMA) determination of compositional gradients of trace metal-ion content in bone tissue, (iii) the absence of measurable quantities of V in bone tissue, and (iv) the difference in local tissue accumulation between Ti, released from Ti specimens, and Ni, released from stainless steel specimens.

Alloys↗
PubMed1984

Some thoughts on a possible regulatory approach at EEC level on the classification and labeling of dangerous preparations.

At the present time no European directives on classification, packaging, and labeling exist which cover all dangerous preparations of chemicals. To develop such a directive, the Commission of the European Economic Community services, at the request of and in close collaboration with experts of the member states, has conceived a method for evaluating the toxicity of mixtures of chemicals. This method consists of (a) the characterization of each constituent by means of an index and (b) the classification of preparations for each route of administration on the basis of their toxicity. The index is a figure representing the degree of dilution needed to render the substance not dangerous in the sense of the EEC Directives on the classification of dangerous substances; the highest index among those obtained for acute and chronic toxicity is taken to characterize the substances. An indication of toxicity is obtained by applying the simple equation sigma (P X I), where P is the percentage and I is the index of each constituent. The most stringent classification among those obtained for the three routes of administration is taken for the final classification of the preparation on the basis of its acute and chronic toxicity. Other toxicological effects such as irritation, corrosion, sensitization, mutagenesis, teratogenesis, and carcinogenesis are not considered.

Animals↗