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Biomedical subjects

M Richter

Publications and source records attributed to M Richter.

At least 235 records · Page 13Linked to original sources
PubMed1992

Unilateral and bilateral corticotomies for correction of maxillary transverse discrepancies.

Surgically-assisted rapid maxillary expansion in adults has been proved effective in overcoming the strong resistance of the maxillary complex after growth is completed, particularly after the second decade of life. The aim of this study was to describe the dental and the skeletal expansion and relapse, as well as the amount of tipping of the two maxillary bones and first permanent molars, during a rapid maxillary expansion procedure combined with unilateral and bilateral corticotomies. The sample consisted of four adult patients, two presenting with bilateral and two with unilateral cross-bite. Records were taken before and after rapid maxillary expansion, at the end of retention and at least 12 months post-retention. In the cases of bilateral cross-bite the same amount of skeletal expansion was observed on both sides. The angular changes measured at the upper first molars indicated important tipping on both sides, which tended to relapse moderately during the retention and post-retention period. Following unilateral surgery, the operated side showed more than twice the amount of skeletal expansion than the non-operated side. The angular changes presented twice as much tipping and relapse on the operated side. The results of this study demonstrate that unilateral cross-bites in adults can be corrected with unilateral corticotomy and rapid maxillary expansion using the contralateral non-operated side as anchorage. Stability appeared satisfactory in all cases.

Activator Appliances↗
PubMed1992

Pulsed-field gel electrophoresis for epidemiologic studies of Campylobacter hyointestinalis isolates.

Campylobacter hyointestinalis was isolated from five members of the same family who had previously consumed raw milk. Pulsed-field gel electrophoresis of genomic DNAs from the five strains, after digestion with restriction endonuclease SalI, revealed that three strains had identical genome patterns and therefore appeared to be related, whereas the other two had completely different genome patterns and appeared to be unrelated. We report here for the first time the isolation of C. hyointestinalis from family members who had consumed raw milk. Our study also demonstrates the usefulness of pulsed-field gel electrophoresis for epidemiologic studies of this unusual campylobacter.

Bacteriological Techniques↗
PubMed1992

Preoperative and postoperative hemostatic profiles of dogs undergoing ovariohysterectomy.

Hemostatic profiles were evaluated in 15 healthy dogs immediately before and 24 hours after celiotomy for routine ovariohysterectomy. Prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin degradation products, antithrombin III activity, platelet count, and hemogram were measured. There were no significant changes in prothrombin time, activated partial thromboplastin time, fibrin degradation products, antithrombin III activity, or platelet count. Fibrinogen concentration was significantly higher following surgery. Postoperative leukocyte differential counts were typical of stress leukograms, and were characterized by leukocytosis, neutrophilia, lymphopenia and eosinopenia. Mild decreases in packed cell volume, red blood cell count and hemoglobin concentration were consistent with minor blood loss during surgery or fluid retention and hemodilution postoperatively. It was concluded that celiotomy and routine ovariohysterectomy in healthy dogs did not alter hemostatic profiles 24 hours after surgery. Abnormal postoperative hemostatic profiles should not be attributed to surgery alone; other causes of abnormal hemostatic profiles should be investigated.

Animals↗
PubMed1991

[Headache, hypertension].

Headache and hypertension were the main clinical symptoms in this slim 77-year-old lady. Because the hypertension presented as paroxysmal and was combined with palpitations, dizziness, and sweating the suspicion of a phaeochromocytoma arouse. The vanillyl mandelic acid in the urine was elevated. As further investigation revealed that this elevation was due to medication with L-dopa because of Parkinson-syndrome. A proper history of the patients' medication or alternative laboratory tests prevent false conclusions.

Adrenal Gland Neoplasms↗
PubMed1991

Age-related enhancement and suppression of a T-cell-dependent antibody response following stressor exposure.

The effects of uncontrollable footshock on the peak splenic plaque-forming cell (PFC) response and serum antibody titers to sheep red blood cells (10(6) cells ip) were assessed in 3-month-old and 9-month-old male CD-1 mice. Exposure to uncontrollable footshock provoked an immunosuppression in mice of both age groups. The critical period for the induction of the suppression (i.e., 72 hr after inoculation) did not differ between the 3-month-old and 9-month-old mice; however, the suppression could be provoked more readily in the older animals. In the 9-month-old mice, the variations of immune activity were dependent on the severity of the stressor and the time of stressor application. Specifically, in contrast to the suppression induced by footshock, a relatively mild stressor such as exposure to a novel environment effectively increased the PFC response. A marked enhancement of the PFC response and antibody titers was evident in older animals that were shocked immediately or 24 hr after inoculation. The possibility exists that stressor application in older mice may influence regulatory processes that are associated with an immune response and that the nature of these regulatory mechanisms may vary with the time after antigenic challenge.

Aging↗
PubMed1991

Identification of the major fibroblast growth factors released spontaneously in inflammatory arthritis as platelet derived growth factor and tumour necrosis factor-alpha.

Rheumatoid arthritis is characterized by chronic inflammation and proliferation of a number of important elements within the joint including the synovial fibroblasts. Elevated levels of a number of cytokines such as Il-1, IL-2, IL-6, interferon-gamma (IFN-gamma), transforming growth factor-beta and tumour necrosis factor-alpha (TNF-alpha) have been detected in the synovial fluid of patients with rheumatoid arthritis and other inflammatory arthritides. It seems likely that local release of such mediators may be responsible for the proliferation and overgrowth of connective tissue elements in these disorders. In order to ascertain whether there was evidence to suggest local production or release of fibroblast growth factors in the joint in inflammatory arthritis, and to determine their identity, cells were obtained from the synovial fluid of 15 patients with chronic inflammatory arthritides. All subjects' synovial fluid cells spontaneously released growth factor activity for fibroblasts. This was present in large amounts, being detectable in culture supernatants diluted to a titre of at least 1/625. By a series of depletion experiments using solid-phase bound antibodies to cytokines, it was possible to demonstrate that this activity was due to TNF-alpha and platelet-derived growth factor (PDGF). Thus, this study showed for the first time that functionally active PDGF was released from synovial fluid cells. Both PDGF and TNF-alpha appeared to contribute in approximately equal amounts to this fibroblast growth factor activity, and were synergistic in effect. Thus this study provides evidence for the local production and release of these two cytokines and suggests that together they are the dominant factors in fibroblast proliferation within the synovial cavity.

Arthritis, Rheumatoid↗
PubMed1991

A non-cytotoxic suppressor of immunoglobulin synthesis and secretion by B cells of normal humans and patients with rheumatoid arthritis and systemic lupus erythematosus.

A factor secreted by thymocytes of immunized rabbits totally suppressed both the initiation of, and ongoing synthesis and secretion of, lectin (PWM)-induced synthesis of IgM and IgG immunoglobulins by the circulating B lymphocytes of normal humans, and of twenty consecutive patients with rheumatoid arthritis and twelve consecutive patients with systemic lupus erythematosus. The suppressor factor, referred to as human Ig synthesis/secretion suppressor factor or HISSF, is not HLA restricted in its activity and is not cytotoxic to the circulating human mononuclear cells (B cells, T cells, Null cells and monocytes). It was demonstrated that T cells precultured with HISSF were transformed into suppressor cells which, when added to fresh cultures of autologous B cells, suppressed the synthesis and secretion of IgM and IgG. On the basis of its suppressive and non-cytotoxic properties in vitro, HISSF may be an effective immunosuppressant in the treatment of patients with autoimmune diseases.

Animals↗
PubMed1991

[Treatment of two cases of periodic sleep apnea by maxillo-facial surgery].

Juvenile temporomandibular bony ankylosis may generate micro- and retroposition of the mandible. Collapse of the upper airway during sleep due to muscle atonia awakens the patient, leading to compensative diurnal hypersomnia. In severe cases, alveolar hypoventilation may result in anoxic seizure, sudden death or development of life threatening cor pulmonale. The corrective surgical procedure for adult is an anterior sagittal osteotomy and in the growing child, costochondral grafting is proposed. Pre and post operative polysomnograms with recording of oxygen saturation are objective measures of good surgical results.

Ankylosis↗
PubMed1991

Anticoagulant and antithrombotic action of the synthetic thrombin inhibitor D-phenylalanyl-L-prolyl-L-arginine nitrile.

Anticoagulant and antithrombotic effects of a synthetic thrombin inhibitor of the tripeptide type, D-phenylalanyl-L-prolyl-L-arginine nitrile (1), were studied in vitro and in vivo. The anticoagulant action was investigated in common test assays such as thrombin time, activated partial thromboplastin time, prothrombin time and thrombelastography. In human plasma 1 caused a concentration-dependent prolongation of coagulation times and influenced the recalcification measured by thrombelastographic recording. In different models of experimental thrombosis in rats the antithrombotic effectiveness of 1 was shown. I.v. infusion of the thrombin inhibitor reduced or prevented the formation of stasis-induced venous thrombi and of arterial thrombi after electrically induced damage of the vessel wall as well as prolonged the time of a thrombotic occlusion of an extracorporeal arterio-venous shunt. At low doses 1 was also effective in thrombin-induced microthrombosis.

Animals↗
PubMed1991

Functional preprosthetic orthodontics and prosthetic reconstruction with resin-bonded fixed partial dentures.

When a resin-bonded fixed partial denture is planned in the maxillary anterior region, special attention must be paid to occlusal diagnosis. Specific instrumental diagnosis is necessary to define the functionally important factors: the anterior teeth, the occlusal plane, the temporomandibular joint, and their three-dimensional relation. The optimal treatment in an anterior-guided occlusion is a complete integration of the retainers in the given tooth form without altering the original inclination of the palatal guiding surfaces of the anterior teeth. In many cases, preprosthetic orthodontics is indicated because of functional and esthetic reasons. The objective is to achieve an anterior tooth position that allows the retainers of a resin-bonded fixed partial denture to be incorporated with the designed inclination of the guiding surfaces, using noninvasive preparation techniques. Preprosthetic orthodontic treatment planning, possible problems, and limiting factors as well as the subsequent prosthetic reconstruction have been described in detail. The interdisciplinary treatment has to be planned individually for each patient, depending on the functional diagnosis and the clinical and anatomic situation.

Adult↗
PubMed1991

[Edentulous mandible. Contraindications for placement of dental implants].

Between 1987 and 1990, 30 patients with edentulous mandibles have been treated by implantological means. 11 of these patients suffered also from one or more associated disease. The surgical procedure has been carried out without any complication occurrence. One of these patients presented an early osteolysis located in the implant bearing area. From a total number of 42 patients, 12 have been excluded from the implant treatment; 6 of them on psychiatric ground. In conclusion, the absolute and temporary contra-indications are distinguished.

Aged↗