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Biomedical subjects

P Neumann

Publications and source records attributed to P Neumann.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Possibilities and limits of mammography with special reference to breast carcinoma--a comparison of clinical, mammography and histologic diagnoses].

This paper informs about the diagnostical accuracy of clinical examination and mammography at the women's Hospital of the Städtische Klinikum Zwickau from 1989 to 1992 when pathological changes of breasts are diagnosed. A total of 508 diagnostical biopsies was performed during this study period. The histological examination resulted in 276 benign breast lesions and in 232 breast cancers. In 432 cases there was a lump palpable in the breast that was noticed at first by more than 60% of women themselves. 288 (56.7%) correct and 220 (43.3%) false diagnoses were established following the clinical examination. This resulted in a sensitivity of 100% with a specificity of 20.3% and an overall accuracy of 56.7%. However, with the help of mammography 386 (76.6%) pathological changes of breasts were found to be correct. 118 mammograms proved to be false. Out of these 90 (17.8%) had a false-positive diagnosis and 28 (5.6%) a false-negative one. The overall accuracy of mammography was 76.6% (sensitivity 87.9%, specificity 67%).

Biopsy↗
PubMed1996

Flexion-distraction injury of the lumbar spine: influence of load, loading rate, and vertebral mineral content.

The biomechanical response of the lumbar spine to combined flexion-shear loading was determined experimentally. The injury model simulated flexion-distraction trauma to the lumbar spine. Forty-eight lumbar functional spinal units (FSUs) were subjected to dynamic loading to injury with six different load types. The reactive forces and moments and resulting deformity were determined. Static physiologic loading was performed before and after the injurious loading to assess residual injury. The biomechanical response of FSUs was dependent on the amount of load and loading rate. The vertebral bone mineral content explained most of the biologic variation of the results. An osteoporotic or severely degenerated spine will be more easily rendered unstable after trauma with lower deformity. Injury at high loading rates will create instability with lower deformity. In vitro experiments should be performed on entire spinal units and with combined loads.

Acceleration↗
PubMed1996

[Prevention of postoperative nausea and vomiting with single and repeat administration of ondansetron--review of the literature on different administration forms].

Postoperative nausea and vomiting (PONV) is still a common perioperative complication and ondansetron has proved to be an effective antiemetic substance in its prevention. The antiemetic effect of single and repetitive application was evaluated in this study. Fifty-one female patients who underwent gynaecological surgical procedures took part in a random double-blind study. Before the start of anaesthesia, 21 patients (group 1) received either a placebo (six patients), 8 mg ondansetron orally (seven patients) or 16 mg orally (eight patients). The remaining 30 patients (group 2), split into subgroups of ten, were given the same preoperative medication as group 1 plus further doses of the same strength 8 and 16 hours after the first intake of the study medication. Metoclopramide was given intravenously if patients had more than one emetic episode or if they asked for it. Nausea and vomiting were documented up to 24 hours after finishing anaesthesia. Metoclopramide had only to be given to patients who had received a placebo. Nausea was felt by 57% (4/7) of the patients after a single dose of 8 mg ondansetron and by 40% (4/10) of the patients after three doses of 8 mg. One patient (14%, 1/7) with a single dose and two patients (20%, 2/10) with a repetitive dose of 8 mg ondansetron vomited. Following a single dose of 16 mg ondansetron, no patient (0/8) had to vomit and 25% (2/8) of the patients had nausea. There were no complications reported by the patients. Ondansetron was shown to be a well-tolerated antiemetic and seems to have a higher reductive effect on PONV when given in a single dose and not repetitively. The prophylaxis of vomiting seems to be more effective than the reduction of nausea. Follow-up studies will have to clarify our findings.

Adult↗
PubMed1996

[Clinical use of antiemetic drugs for prevention and therapy of postoperative nausea and vomiting].

The incidence of postoperative nausea and vomiting (PONV) has not decreased significantly for decades. This study was done to evaluate whether there is a standard method or a preferred substance in German hospitals in the prophylaxis and treatment of PONV. Twenty-one randomly selected hospitals were asked to give details about substances, doses and application times and forms in PONV prophylaxis and treatment. Most of the patients with a high risk of emesis were treated prophylactically with droperidol. Dosage and time of application were different in each hospital. Metoclopramide was the second most frequently used substance for both prophylaxis and treatment. Dimenhydrinate, triflupromaxzine, promethazine and acupuncture were used less commonly in prophylaxis. Alizapride and ondansetron were used to treat PONV in only two hospitals. Summarising, this study found no routine standard in the prophylaxis and therapy of PONV. Droperidol and metoclopramide were the most frequently used antiemetics. An overview of the antiemetics involved is given.

Antiemetics↗
PubMed1995

Traumatic instability of the lumbar spine. A dynamic in vitro study of flexion-distraction injury.

STUDY DESIGN: This in vitro study determined the effect on the lumbar spine of a dynamic flexion-distraction loading simulating a lap seatbelt injury. The proportion by which the forces and the moments contributed to the injury of the lumbar spinal segment in such a situation was analyzed. The remaining stability of the injured lumbar motion segment was determined together with the threshold for lumbar spine instability in such an injury. OBJECTIVES: Based on the experimental results in this study, radiographic guidelines for instability criteria in lumbar and thoracolumbar dislocations in the sagittal plane without concomitant compression fracture of the middle column were proposed. SUMMARY OF BACKGROUND DATA: A number of check-lists and guidelines were suggested for the diagnosis of spinal instability after trauma, but no conclusive system was established. Those systems were mostly based on experiments performed on spinal segments after sequential ablation of ligaments and facet joints followed by static, unidirectional physiologic loading. We believed that there was a need for more profound knowledge of spinal injury and for instability criteria of lumbar spinal injuries based on more realistic experimental data simulating the clinical situation. In our injury model, we decided to study the biomechanic outcome of a flexion-distraction injury similar to seatbelt type injury seen in frontal motor vehicle collisions. METHODS: Twenty lumbar functional spinal units were first loaded statically with a physiologic flexion-shear load to determine angulations and displacements under noninjurous conditions. Dynamic flexion-shear loading to injury with two different load pulses was then applied. Static physiologic load was then again applied to determine any permanent residual deformation. RESULTS: The viscoelastic effect of loading rate on translatory and angular displacements and the values for translatory and angulation displacements at first sign of injury (yield) and at failure were determined. CONCLUSIONS: Radiographic guidelines for instability criteria in lumbar and thoracolumbar fracture-dislocations without concomitant posterior vertebral body compression are proposed: 1. Instability exists if there is a kyphosis of the lumbar motion segment > or = 12 degrees (impending instability) or > or = 19 degrees (total instability) on lateral radiographs. 2. Relative increase in interspinous process distance > or = 20 mm (impending instability), > or = 33 mm (total instability) on anteroposterior radiographs.

Accidents, Traffic↗
PubMed1995

Volunteer low-risk outpatient surgery for uninsured patients in San Francisco. The Ambulatory Surgery Access Coalition.

OBJECTIVE: To provide uncompensated elective low-risk outpatient surgery for uninsured patients through a coalition of volunteer physicians, nurses, and hospitals. DESIGN: Description of the process of establishing the Ambulatory Surgery Access Coalition (ASAC), the political and administrative obstacles encountered, and the clinical results of treatment of the first 25 patients in the pilot project. SETTING: The ASAC includes the Kaiser Foundation Hospital, San Francisco, Calif, the University of California, San Francisco, the San Francisco General Hospital (SFGH), the San Francisco Department of Public Health, the San Francisco Consortium of Community Clinics, the Northern California Chapter of the American College of Surgeons, and the San Francisco Medical Society. A pilot program of uncompensated outpatient surgery was performed at the Kaiser Foundation Hospital. PATIENTS: Twenty-nine patients were referred to the ASAC between January 1 and November 1, 1994. Twenty-six patients were judged to be candidates for surgery, and 25 patients met the criteria for the ASAC program. One patient was referred to SFGH for treatment because of a perceived increased risk for hospitalization after surgery. RESULTS: Twenty-one patients underwent herniorrhaphy; three, excision of large inclusion cysts; and one, anal fistulotomy. Seventeen procedures were done under local anesthesia, seven under general anesthesia, and one under spinal anesthesia. None of the patients required hospital admission. No wound infections occurred. CONCLUSION: The ASAC successfully provided uncompensated low-risk outpatient surgery to 25 low-income uninsured patients in San Francisco. The coalition hopes, first, to include other San Francisco hospitals and surgical specialties, and second, to serve as a model for other communities throughout the country.

Ambulatory Surgical Procedures↗
PubMed1995

Colorimetric analyses of various light sources for the D-15 color vision test.

Colorimetric analyses were performed in both normal trichromatic and dichromatic color spaces to determine whether several light sources were suitable illuminants for the Farnsworth-Munsell Panel D-15 (D-15) color vision test. Results for fluorescent lamps showed that lamps with a correlated color temperature (CCT) of 7200 degrees K and a general color rendering index (GCRI) of at least 90 are acceptable substitutes for illuminant C. Predictions for filtered tungsten light indicated that lights with a color temperature near 5000 degrees K are unsuitable because of nonuniformities in the glass daylight filter transmittance. Conclusions based on these analyses are conservative because, with exception of the GCRI, color adaptation effects were not taken into account.

Adaptation, Ocular↗
PubMed1994

Effect of strain rate and bone mineral on the structural properties of the human anterior longitudinal ligament.

The effect of strain rate and bone mineral content on the biomechanical properties of the human lumbar anterior longitudinal ligament-bone complex was studied. Tensile structural properties were determined for 54 such preparations subjected to distraction rates ranging from 0.1-230 mm/sec. The ultimate load as well as the stiffness of the bone-ligament complex increased more than 50% over this strain rate range. A high correlation between bone mineral and structural properties of the ligament-bone complex was also noted. These findings suggest that, in development and construction of spine models for prediction of injury risks, one should consider the effect of different loading rates as well as the inherent properties (i.e., bone mineral content) of the biological material.

Adult↗
PubMed1994

Aging, vertebral density, and disc degeneration alter the tensile stress-strain characteristics of the human anterior longitudinal ligament.

The mechanical properties of the human lumbar anterior longitudinal ligament were investigated, and the influence of aging, disc degeneration, and vertebral bone density on these properties was determined. Tensile mechanical properties of the vertebra-anterior longitudinal ligament-vertebra complex were determined for 16 segments from cadavera of individuals who had been 21-79 years old (mean, 52.1 years) at the time of death. Regional strain patterns associated with three sites across the width and three sites along the length of the anterior longitudinal ligament were measured with use of a video-based motion analysis system. In the young, normal anterior longitudinal ligament, the elastic moduli of the insertion and substance regions of the ligament were similar (approximately 500 MPa). During aging (21-79 years), the elastic modulus of the substance region increased 2-fold, whereas the elastic modulus of the insertion decreased 3-fold; this resulted in an approximately 5-fold difference in elastic modulus between these regions in the older spine. The strength of the bone-ligament complex decreased approximately 2-fold (from 29 to 13 MPa) over this same age range. The outer portion of the anterior longitudinal ligament consistently had the highest peak tensile strains (11.8 +/- 2.7%) in all of the specimens examined. Preparations with nondegenerated discs and high bone density were significantly stronger (66%) and failed in the ligament substance; in contrast, segments from older individuals with degenerated discs and lower bone density failed in the ligament insertion regions.

Adult↗
PubMed1993

Autoradiographic localization of prazosin and rauwolscine binding sites in the human kidney.

In the human kidney, binding sites for the alpha 1-adrenoceptor antagonist 3H-prazosin and the alpha 2-adrenoceptor antagonist 3H-rauwolscine were localized and quantified by in vitro autoradiography. 3H-prazosin binding was found predominantly in the renal cortex. In the medulla, tubular structures were also specifically labelled. No binding sites, however, were detected in association with glomeruli or large blood vessels. 3H-rauwolscine labelled the medullary vascular bundles intensively, but no binding sites were associated with glomeruli or other cortical structures. Thus, the binding pattern for 3H-prazosin is quite similar in both human and rat renal cortex. There are, however, distinct differences between human and rat kidneys in the distribution of the alpha 2-adrenergic binding sites visualized with the antagonist 3H-rauwolscine.

Animals↗
PubMed1993

A method for studying the biomechanical load response of the (in vitro) lumbar spine under dynamic flexion-shear loads.

A method was developed to study the biomechanical response of the lumbar motion segment (Functional Spinal Unit, FSU) under a dynamic (transient) load in flexion. In order to inflict flexion-distraction types of injuries (lap seat-belt injuries) different load pulses were transferred to the specimen by means of a padded pendulum. The load response of the specimen was measured with a force and moment transducer. The flexion angulation and displacements were determined by means of high-speed photography. Two series of tests were made with ten specimens in each and with two different load pulses: one moderate load pulse (peak acceleration 5 g, rise time 30 ms, duration 150 ms) and one severe load pulse (peak acceleration 12 g, rise time 15 ms, duration 250 ms). The results showed that the moderate load pulse caused residual permanent deformations at a mean bending moment of 140 Nm and a mean shear force of 430 N at a mean flexion angulation of 14 degrees. The severe load pulse caused evident signs of failure of the segments at a mean bending moment of 185 Nm and a mean shear force of 600 N at a mean flexion angulation of 19 degrees. Significant correlations were found between the load response and the size of the specimen, as well as between the load response and the bone mineral content (BMC) in the two adjacent vertebrae. Comparisons with lumbar spine response to static flexion-shear loading indicated that the specimens could withstand higher bending moments before injury occurred during dynamic loading, but the deformations at injury tended to be smaller for dynamic loading.

Acceleration↗
PubMed1993

The ultimate flexural strength of the lumbar spine and vertebral bone mineral content.

Flexion-distraction injuries (lap seat-belt injuries resulting from car accidents) were simulated by exposing 16 lumbar functional spinal units (FSUs) to a combined quasistatic load of bending and shearing in the sagittal plane. The load response of the FSU was measured by means of a force and moment transducer. Displacements and angulations were measured and calculated by means of dial gauges and photographs taken after each loading step. The mean angulation between the vertebrae just before total rupture was 20 degrees. The ultimate values of bending moment, shear force, and bending stiffness were correlated with the bone mineral content (BMC), and so were the horizontal and vertical displacements determined around the yield point on the load-displacement curve.

Accidents, Traffic↗
PubMed1993

Structural properties of the anterior longitudinal ligament. Correlation with lumbar bone mineral content.

The relationship between the amount of bone in the lumbar spine and ligamentous properties has not been studied. This article reports the tensile structural properties of bone-ligament-bone preparations of the anterior longitudinal ligament from 15 human lumbar spine segments. Significant correlations were found between the vertebral bone mineral content expressed as BMC (g/cm) and BMA (g/cm2) and BMD (g/cm3) and the structural properties of the vertebral bone-anterior longitudinal ligament-bone complex determined at yield and failure. These findings suggest that the amount of bone tissue in the spine may be functionally related to structural properties of the spinal ligaments.

Adult↗
PubMed1992

Mechanical properties of the human lumbar anterior longitudinal ligament.

A new technique incorporating a motion analysis system and a materials testing machine was used to investigate regional differences in the tensile mechanical properties of the lumbar spine anterior longitudinal ligament (ALL). Bone-ALL-bone specimens were prepared from young human cadaveric motion segments with no disc or bony pathology. Each specimen was distracted until failure at a constant crosshead displacement rate of 2.5 mm s-1 (approximately 1.0% strain per second). Strains were evaluated from digitized video recordings of markers attached to the ALL at 12 sites along its length and width, including the ligament substance and insertions. The 'overall' strain in the ligament was calculated from the outermost pairs of markers along the ligament length. The average tensile strength, the 'overall' tensile modulus and the 'overall' strain of the ALL at failure were 27.4 MPa (S.D. 5.9), 759 MPa (S.D. 336) and 4.95% (S.D. 1.51), respectively. Large and significant variations in the strains were present along the width and length of the ALL. Peak substance strains were over twofold greater than peak strains at the ligament insertion sites, whereas across the ligament width, peak strains in the outer portion of the ligament were over 40% greater than in the central region. Failure consistently occurred in the ligament mid-substance and ultimate strains at the ligament failure site averaged 12.1% (S.D. 2.3). These results indicate that the strains are highly nonuniform in the normal ALL.

Adult↗
PubMed1992

Prevalence of antibodies to Borrelia burgdorferi in serum and cerebrospinal fluid samples from patients with neurological disorders in Berlin.

Paired serum and cerebrospinal fluid (CSF) samples from 800 patients of a neurological department were tested for antibodies to Borrelia burgdorferi. A flagellum enzyme-linked immunosorbent assay was used for antibody screening. All serum/CSF pairs with any elevated antibody response were also tested by Western blotting a method for confirmation. 65 patients (8.1%) had serum IgG antibodies in ELISA and 22 of these patients (2.8%) were confirmed by Western blot. 20 patients (2.5%) had elevated antibody titres in CSF by ELISA and 12 (1.5%) reacted in the Western blot. Clinical features of Bannwarth's syndrome were present in 12 patients (1.5%) and 4 patients (0.5%) showed other manifestations of Lyme borreliosis. All patients with Bannwarth's syndrome were seropositive by both methods and 10 had elevated antibody activity in the CSF proved by the two methods. The combination of a sensitive ELISA for screening and a sensitive and specific Western blot for confirmation reduced the number of false positive results but kept its standard in detecting antibodies in patients with active disease.

Adult↗
PubMed1992

The mechanism of initial flexion-distraction injury in the lumbar spine.

The threshold for flexion-distraction injuries was determined on lumbar functional spinal units exposed to a combined flexion-shear load in the sagittal plane. The specimens could resist a bending moment of 121 Nm and a shear force of 486 N at the first sign of a permanent deformation of the osteoligamentous components, which occurred at 78% of the assumed ultimate strength of each specimen. The flexion angulation was 16 degrees. The bone mineral content determined in adjacent vertebrae by means of dual photon absorptiometry was an accurate predictor of structural properties of the entire functional spinal unit even at the first sign of a substantial structural injury and not only at ultimate failure as previously demonstrated.

Bone Density↗
PubMed1992

[Correlation between neurologic disease and Borrelia burgdorferi antibodies in 800 paired serum/cerebrospinal fluid samples].

Paired serum and cerebrospinal fluid (CSF) samples from 800 patients of a neurological clinic were tested for antibodies to Borrelia burgdorferi. A flagellum enzyme-linked immunosorbent assay was used for antibody screening. All serum/CSF pairs with any elevated antibody response were also tested by a Western blot, a method for confirmation. 65 patients (8.1%) had serum IgG antibodies on ELISA screening and 22 of these (2.8%) were confirmed by Western blot. 20 patients (2.5%) had elevated antibody titers in CSF by ELISA and 12 of these (1.5%) reacted to the Western blot. Clinical features of Bannwarth's syndrome (BS) were present in 12 patients (1.5%) and four patients (0.5%) showed other manifestations of Lyme borreliosis. All patients with Bannwarth's syndrome were positive in serum by both methods and 10 had elevated antibody activity in the CSF proven by the two methods. The combination of a sensitive ELISA for screening and a sensitive and specific Western blot for confirmation reduces the number of positive results but is sensitive in detecting active disease.

Antibodies, Bacterial↗