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Biomedical subjects

N Haas

Publications and source records attributed to N Haas.

At least 145 records · Page 8Linked to original sources
PubMed1990

[Treatment of distal radius fracture--diagnosis and therapy of local concomitant injuries].

In a high percentage the accompanying local injuries in Colles' type fractures of the distal radius are related to lesions of the triangular fibrocartilage complex (TFCC) and the distal radioulnar joint (DRUG). Frequency and importance of these local injuries concerning the long-term result after distal radius fractures are described and diagnostic and therapeutical proceedings are presented.

Fracture Fixation, Internal↗
PubMed1990

[The pedestrian-automobile accident at lower velocity. Experimental studies of biomechanical and clinico-prognostic topics].

The influence of bumper configuration on injury patterns resulting from car/pedestrian collisions were analyzed. 18 experimental settings were carried out on the deceleration device of the Institute of Forensic Medicine of the Medizinische Hochschule Hannover using a middle class passenger car at collision speed of 32 km/h. Three modifications of the standard bumper design did not reduce the severity of injuries induced by collision. Comparatively promising results were given by another bumper construction consisting of an additional bumper relatively easy to deform attached to the standard variant at a level of 12 cm below. Authors discuss findings regarding injury patterns, injury mechanisms and subsequent implications. Based on trauma surgeons' experience it is suggested not only to aim on reduction of bone injuries. Major attention has to be paid on improving rehabilitation prognosis and on reducing medical treatment expenses. According to data available soft tissue damage is of major importance and needs to be quantified before taking one particular bumper construction as pedestrian friendly design.

Accidents, Traffic↗
PubMed1990

[Stabilization of open tibial fracture by an external fixator. Advantages through supplemental screw osteosynthesis].

One hundred thirty-two open tibial shaft fractures were treated by unilateral external fixation. In order to evaluate the usefulness of supplemental lag screw fixation, we compared forty-four reexamined fractures in which only external fixation was utilized with fifty-five reexamined fractures, stabilized with supplemental lag screws and external fixation. We did not find significant differences in time to full-weight bearing (17.1 vs. 15.6 weeks), time to union (18.7 vs 18.0 weeks), incidence of delayed union [as defined by time to union over 32 weeks (10.9% vs. 11.4%)], incidence of osteomyelitis (5.4% vs. 4.5%), or incidence of malunion [axial malalignment greater than 5 degrees (12.7% vs. 11.4%)]. Clinically significant differences were found demonstrating a twofold increase in refracture rate in the group with supplemental lag screws (10.9% vs. 4.5%) and requiring twice as many bone grafting procedures to achieve union (65.5% vs. 29.5) than did the group treated by external fixation alone. Therefore we do not recommend the routine use of supplemental lag screw fixation.

Adolescent↗
PubMed1989

Does magnetic resonance imaging compromise integrity of the blood-brain barrier?

It has been reported that a standard clinical procedure of magnetic resonance imaging (MRI) carried out experimentally in the rat caused temporary opening of the blood-brain barrier. Electron micrography indicated blood-to-brain movement of horseradish peroxidase, a protein tracer that does not normally permeate the barrier. In the present study, permeability-area products (PA), describing the limited permeation of blood-borne [14C]sucrose into brain parenchyma, were measured in anesthetized rats subjected either to 23 min of MRI, to osmotic barrier opening by intracarotid infusion of hypertonic arabinose, or to control conditions. Osmotic opening caused manyfold increases in PA whereas MRI produced no change. The proposal that MRI can compromise integrity of the blood-brain barrier is not supported by these findings.

Animals↗
PubMed1989

Colchicine lesions of ventromedial hypothalamus: effects on regulatory thermogenesis in the rat.

Experiments were carried out to test whether the ventromedial hypothalamus (VMH) is the site of a pathway that stimulates thermoregulatory heat production in brown adipose tissue (BAT). Adult Sprague-Dawley rats received bilateral 50 nl microinjections of colchicine solution into the VMH (0.1, 0.32, 1.0 or 3.2 micrograms per side). Beginning a day later, hyperphagia developed consistently with 0.32 microgram colchicine; and with higher doses there appeared the additional effect that for several days rats developed hypothermia when placed temporarily at 6 degrees C. The degree of hypothermia was limited by activation of nonshivering thermogenesis (NST) in BAT, as evidenced by increased shivering after propranolol injection to block NST, and by increased GDP binding measured in IBAT mitochondria after cold exposure. The findings suggest that chemical lesioning to induce the VMH hyperphagia syndrome does not produce an obligatory impairment of thermoregulation against cold unless the dose of neurotoxin and lesion area extends beyond that which underlies the overeating response. Furthermore, when tolerance to cold is thus compromised, the effect is not readily explained in terms of simply disconnecting a proposed stimulatory pathway from the VMH to BAT.

Animals↗
PubMed1989

[Distal radius fracture. Fracture stabilization with biodegradable osteosynthesis pins (Biofix). Experimental studies and initial clinical experiences].

K-wire stabilization and casting of unstable or intraarticular fractures of the distal radius has proven to be an effective method of treatment since many years. However the need of implant removal after fracture healing is a disadvantage of this method. For this reason we investigated on the use of biodegradable implants in a fracture model of the distal radius. The biomechanical testing with Polydioxanon-(PDS)-pins (Ethipin) showed too small primary stability for the use in vivo. Osteosyntheses with three Polyglycolacid-(PGA)-rods Biofix compared with three K-wires 1.6 mm on the other hand showed 82% initial stability. From May to September 1988 typical distal radius fractures in 11 patients have been stabilized with Biofix-rods. The result of primary reduction could be obtained in all cases. These first experiences suggested, that stabilization of distal radius fractures with Biofix-rods might alternatively be performed instead of K-wire pinning.

Adult↗
PubMed1989

[Management of femur shaft fracture in the growth age with the fixateur externe].

Non-operative management is still the treatment of choice today for femoral shaft fractures in children. Indications for operative intervention would include: - the child with multiple injuries, particularly with severe head injuries, in those patients with severe soft tissue damage associated with the fracture; in cases where the reduction is difficult to maintain, as in subtrochanteric fractures; and in children who are not suitable for management with traction. Since 1984, 16 children have had their femoral shaft fractures stabilized by external fixation (Monofixateur) here in the Trauma Department of the Hannover Medical School. The mean age of the patients was 10.3 years (seven to sixteen years). All cases were closed fractures with mild or moderate soft tissue damage. Eleven of the patients had a multiple injury, and four had subtrochanteric fractures. The external fixation remained in place for a mean of 63 days in those patients exclusively treated by this method. In four of the earlier cases there was a Schanz's screw infection and three of these required removal of the external fixation and treatment in a hip spica. After modifying the technique of Schanz's screw insertion, no further infections were seen. Fourteen of the sixteen children were reviewed, with a mean follow up of 21.7 months. None of the children who had been completely managed by this fixation had any clinically relevant malalignment. Six cases had leg lengthening of up to two centimetres. Leg length differences were seen more frequently and more severely in those cases where external fixation was delayed.

Adolescent↗
PubMed1989

[Anatomy of the knee joint and its clinical relevance].

The stability of the knee joint is ensured by dynamic and static structures. The most important medial structures are the medial collateral ligament, medial capsular ligament, posterior oblique ligament, semimembranous muscle, and the pes anserinus group. The main supportive structures on the lateral side include the iliotibial band, lateral collateral ligament, lateral capsular ligament, popliteal tendon, arcuate ligament, and the biceps muscle. The cruciate ligament pillar is the center of rotation. The classification of knee instability requires new orientation that places the main emphasis on the translation of the joint compartments and the description of the injured structures.

Humans↗
PubMed1989

[Injuries of the acromio- and sternoclavicular joint--surgical or conservative treatment?].

At the acromioclavicular (AC) joint we distinguish between horizontal instability caused by damage to the AC ligament from vertical instability caused by damage to the coracoclavicular liagments. The most common mechanism of injury is direct force resulting from a fall onto the point of the shoulder. The injury is classified according to the amount of damage brought about by a given force. Horizontal and vertical instability have to be evaluated by special radiographic views. Types I and II are treated by a sling worn for a few days and the application of ice bags. In type III injuries the patient's age, job and acitve pursuits determine whether or not surgery is indicated. In type IV-VI injuries we always perform the operation. We use a resorbable cerclage between the clavicle and the coracoid process and suture all torn ligaments. In the sternoclavicular joint too, the ligamentous stability is of the utmost importance. The sternoclavicular ligament limits the ante- and retroversion of the clavicle, while the costoclavicular ligament limits the upward movement. The direction of subluxation or luxation has to be evaluated by means of an oblique view X-ray with a cephalic tilt of the tube through 40 degrees or by a computed tomogram. In the case of an acute injury closed reduction should always be attempted. Open recuction should only be performed in cases of persistent posterior luxation, because of the numerous complications that are possible in such cases.

Acromioclavicular Joint↗
PubMed1989

[Biochemical and mathematical studies of the pre-bending and pre-stressing of the small fragment DC plate].

The effects of prebending and prestressing in compressional osteo-synthesis with application of the AO small-fragment DC plate on the bones of the forearm were examined. The necessary prestress force, the angle of prebending and the resulting center of compression in the fracture site were experimentally examined. These experiments were performed on fresh cadaver bones using the ulna and the radius. Additionally, after applying small-fragment DC plates with varying angles of prebending and varying forces of prestressing on perpendicular shaft osteotomies, stability tests were carried out. A theoretical analysis of the experiments performed was computed using the finite element method.

Biomechanical Phenomena↗
PubMed1989

[The surgical treatment of injuries of the cervical spine].

The authors' ideas on the management of acute and chronic cervical spine injuries are presented. Unstable fractures and dislocations of the lower cervical spine should be reduced as soon as possible. Most frequently, the authors use the anterior approach and the Smith-Robinson technique with the addition of a H-shaped plate. Posterior fusion is mainly indicated for the release of irreducibly locked facets. Unstable odontoid fractures, especially those in group II according to Anderson and d'Alonzo, are stabilized by internal fixation with a screw. Between 1971 and 1987, 263 patients with lesions of the cervical spine were treated operatively: of these, 169 had acute and 32 chronic injuries; 47 patients had primary tumors or metastases; 15 suffered from arthritis, spondylodiscitis or congenital deformity. The findings in 92 patients (group I) with acute and 24 (group II) with chronic injuries at follow-up are reported. Among the 53 patients in group I with neurologic failure, an improvement was noted in 45 (85%); in 30 cases there was complete restoration of function and 72% of the injured patients became symptom-free. In 71% of those with acute and 58% of those with chronic injuries normal mobility was observed. Regardless of neurologic failure, 89% of patients in group I were able to work after 5 months. The rate of pseudarthrosis was 2%. The risks involved in anterior interbody fusion in the cervical spine are small when a careful and standardized operation technique is used. This allows early functional treatment and shortens the rehabilitation time.

Adolescent↗
PubMed1989

[Results of treatment of 202 fresh tibial shaft fractures, managed with unilateral external fixation (monofixateur)].

From 1982 to 1986, a total of 202 lower leg fractures (70 closed, 132 open fractures) were treated with a monoexternal fixation device, and 148 cases were included in the follow-up study. The mean healing time was 15.4 weeks for closed fractures and 18.4 weeks for open fractures. Infection was occurred in 3.4% of the patients followed up (5.1% open fractures, as 0% closed fractures), aseptic delayed in 8.8%, and pin tract infection in 2.5%. The group of patients with open fractures treated with additional lag screws (n = 74) showed a higher rate of refractures (10.9% vs 4.5%) and bone grafting (65.5% vs 29.5%) than the control group without lag screws (n = 58). The healing times (15.8% vs 15.5 weeks) and rates of non-union (10.9% vs 11.4%) were similar in both groups. Among 14 cases of secondary intramedullary nailing, osteitis occurred in 2. In the dynamized group (n = 53) healing time was reduced to 16.0 weeks, as against 18.0 weeks in the n-dynamized group (n = 95).

Adolescent↗
PubMed1988

The beta-tubulin gene family of Arabidopsis thaliana: preferential accumulation of the beta 1 transcript in roots.

The genome of Arabidopsis thaliana (L.) Heynh. was shown to contain a beta-tubulin gene family consisting of at least seven distinct genes and/or pseudogenes. Genomic clones of five different beta-tubulin genes and/or pseudogenes have been isolated and partially characterized. The complete nucleotide sequence of one A. thaliana beta-tubulin gene, designated beta 1, has been determined. A comparison of the predicted amino acid sequence of the A. thaliana beta 1-tubulin with the predicted sequences of beta-tubulins of animals and protists indicated that this plant beta-tubulin shows a high degree of homology with other beta-tubulins. However, the beta 1-tubulin contains a novel single amino acid insertion at position 41. The A. thaliana beta 1-tubulin gene is transcribed, as shown by RNA blot hybridization and S1 nuclease analyses. A 3'-noncoding gene-specific probe was used to examine the expression of the beta 1-tubulin gene in leaves, roots, and flowers by blot hybridization analyses of total RNA isolated from these tissues. The results showed that the transcript of the beta 1 gene accumulates predominantly in roots, with low levels of transcript in flowers, and barely detectable levels of transcript in leaves. A second genomic clone was shown to contain two essentially identical beta-tubulin coding sequences in direct tandem orientation and separated by 1 kb.

Amino Acid Sequence↗