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Biomedical subjects

J S Jensen

Publications and source records attributed to J S Jensen.

At least 19 recordsLinked to original sources
PubMed1995

Innovations in acrylic bone cement and application equipment.

A new bone cement was developed with the purpose of reducing the adverse biological effects during cementation of implants. This bone cement is characterized by lower exotherm, low release of monomer, low residual content of monomer, and retained physical properties. The essential innovation was substitution of half of the methylmethacrylate (MMA) in the monomer with long chain, high molecular weight, less volatile, and less soluble methacrylates (n-decylmethacrylate, isobornyl-methacrylate), as well as alteration of the accelerator system to a mix of dihydroxypropyl-p-toluidine and N,N-dimethyl-p-toluidine. The powder contains butylmethacrylate-MMA copolymers. These measures lower the glass-transition temperature, and permit more complete mixing in an integrated package, mixing, and delivery system consisting of a vacuum packed, double chamber pouch. The porosity was reduced to about 2% and the largest voids measured 0.1 mm. The polymerization exotherm was reduced to 58 degrees C. The compressive strength was 82 MPa, the four-point bending strength 55 MPa, the flexural modulus 2.24 GPa, the tensile strength 32 MPa, and the shear strength 36 MPa. The fracture toughness was 0.89 MPa square root of cm. These mechanical properties together with the fatigue life were on level with manually mixed, conventional PMMA bone cements.

Biocompatible Materials↗
PubMed1995

Nosocomial legionellosis in three heart-lung transplant patients: case reports and environmental observations.

Organ transplant recipients are at high risk of contracting Legionnaires' disease in a hospital environment contaminated with legionellae. This study describes the first cases of culture-verified Legionella infections with an established link to potable hospital water in Denmark; three patients operated on at the Cardiopulmonary Transplant Unit, Rigshospitalet, Copenhagen, became infected with legionellae. Environmental and clinical isolates of Legionella pneumophila serogroups 1 and 6 were investigated by restriction enzyme analysis and ribotyping. An ice machine located in the kitchen of the intensive care unit was implicated as a source of infection in two of the three cases.

Cross Infection↗
PubMed1995

Microalbuminuria reflects a generalized transvascular albumin leakiness in clinically healthy subjects.

1. In epidemiological studies microalbuminuria, i.e. slightly elevated urinary albumin excretion rate, predicts increased atherosclerotic vascular morbidity and mortality. This study aimed to test the hypothesis that microalbuminuria in clinically healthy subjects is associated with a systemic transvascular albumin leakiness. In animal experiments the outflux of albumin and lipids to the arterial wall are highly correlated, and both are elevated in atherosclerosis. 2. All participants were recruited at random from a population-based epidemiological study, where the upper decile of urinary albumin excretion rate was 6.6 micrograms/min. Twenty-seven patients with persistent microalbuminuria (urinary albumin excretion rate 6.6-150 micrograms/min), and 56 age- and sex-matched control subjects with persistent normoalbuminuria (UAER < or = 6.6 micrograms/min) were studied. 3. The systemic transvascular albumin leakage was measured as the fractional disappearance rate of 125I-labelled albumin from the total plasma compartment in 1 h after intravenous injection. 4. The fractional disappearance rate of albumin from the plasma compartment was higher in the microalbuminuric than in the normoalbuminuric group [5.8 (95% confidence interval 5.3-6.2; n = 27) versus 5.0 (4.6-5.5; n = 56)%/h, P < 0.05]. The positive correlation between urinary albumin excretion rate on continuous scale (logarithmically transformed) and the fractional disappearance rate of albumin from the plasma compartment [slope 0.4 (95% confidence interval 0.1-0.7; n = 83), r = 0.29, P < 0.005] was independent of age, sex, smoking status, blood pressure, body size, plasma volume, plasma albumin concentration and concentrations of blood glucose, serum insulin and serum lipids. 5. In conclusion, microalbuminuria is an independent marker of systemic transvascular albumin leakiness in clinically healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗
PubMed1995

Reduced glomerular size- and charge-selectivity in clinically healthy individuals with microalbuminuria.

The pathophysiologic mechanism behind microalbuminuria, a potential atherosclerotic risk factor, was explored by measuring fractional clearances of four endogenous plasma proteins of different size and electric charge (albumin, beta 2-microglobulin, immunoglobulin G, and immunoglobulin G4). Twenty-eight clinically healthy individuals with microalbuminuria, defined as a urinary albumin excretion of 6.6-150 micrograms min-1, and 60 matched control subjects were studied. Fractional immunoglobulin G clearance was higher (geometric means (95% confidence intervals)) 3.0 (2.3-3.9) x 10(-6), n = 28, vs. 2.1 (1.8-2.4) x 10(-6), n = 60; P = 0.02), whereas the ratio immunoglobulin G clearance/immunoglobulin G4 clearance was lower (geometric means (95% confidence intervals)) 1.8 (1.4-2.2), n = 28, vs. 2.3 (2.0-2.5), n = 60; P = 0.03) in microalbuminuric than in normoalbuminuric individuals. Fractional beta 2-microglobulin clearance was similar in the two groups. Since total IgG and the IgG4 subclass are of similar size and configuration but electrically neutral and negative, respectively; these findings indicate that microalbuminuria is associated with decreased size- and charge-selectivity of the glomerular vessel wall. Hypothetically, such alterations may reflect generalized vascular abnormalities linking microalbuminuria to atherogenesis.

Adult↗
PubMed1995

Serum sialic acid concentration is elevated in IDDM especially in early diabetic nephropathy.

OBJECTIVES: Elevated serum sialic acid concentration is a strong predictor of cardiovascular mortality in non-diabetic subjects. Because patients with insulin-dependent diabetes mellitus (IDDM) and albuminuria have a highly increased cardiovascular morbidity and mortality, we hypothesized that IDDM patients with albuminuria would have an increased concentration of serum sialic acid. DESIGN: Cross-sectional study. SETTING: Outpatient clinic at Steno Diabetes Centre, Gentofte, Denmark. SUBJECTS: Twenty-six non-diabetic controls and 74 IDDM patients with normoalbuminuria (urinary albumin excretion [UAE] < 30 mg 24 h-1; n = 37), incipient nephropathy (UAE 30-300 mg 24 h-1; n = 20) and clinical nephropathy (UAE > 300 mg 24 h-1; n = 17), matched for sex, age and body mass index (BMI). MAIN OUTCOME MEASURES: Serum sialic acid concentration, concurrent fasting blood glucose, glycated haemoglobin (HbA1c), serum creatinine, plasma fibrinogen and erythrocyte sedimentation rate. RESULTS: Normoalbuminuric patients had a higher serum sialic acid concentration (mmol L-1) than non-diabetic controls (1.83 +/- 0.24 vs. 1.67 +/- 0.26; P < 0.02). Serum sialic acid concentration was further increased in patients with incipient nephropathy (2.02 +/- 0.37; P < 0.03) and in patients with clinical nephropathy (2.13 +/- 0.33; P < 0.002) compared with normoalbuminuric IDDM patients. Serum sialic acid correlated strongly with plasma fibrinogen (r = 0.78; P < 0.0001) and erythrocyte sedimentation rate (r = 0.62; P < 0.0001). In a multiple regression analysis including UAE, retinopathy status, fasting blood glucose, HbA1c, mean blood pressure, serum creatinine, age, BMI, duration and smoking. UAE and fasting blood glucose were the independent variables which correlated significantly with serum sialic acid concentration (P < 0.0001 and P < 0.05, respectively). CONCLUSION: Serum sialic acid is elevated in IDDM especially in albuminuric patients. Whether elevated serum sialic acid is predictive for early diabetic nephropathy and cardiovascular disease in IDDM has to be shown in the future.

Adult↗
PubMed1995

Renal and systemic transvascular albumin leakage in severe atherosclerosis.

Microalbuminuria was recently proposed as a novel atherogenic risk factor. The pathophysiological link between microalbuminuria and atherosclerosis may be mediated through an increased generalized transvascular leakage of albumin. To investigate this hypothesis, urinary albumin excretion and clearance and systemic transvascular albumin leakage (TERalb) were measured in 23 patients with severe clinical atherosclerosis and 25 healthy controls. In addition, renal clearances of three other endogenous plasma proteins (IgG, IgG4, and beta 2-microglobulin) and of creatinine were measured. Measurements of urine and serum proteins were done by enzyme-linked immunosorbent assays. TERalb was measured by the fractional disappearance rate of 125I-albumin from the total intravascular compartment in 1 hour after intravenous injection. Glomerular filtration rate was estimated as creatinine clearance. Urinary albumin excretion (geometric means [95% confidence intervals], 10.5 [6.1 to 18.3] versus 5.7 [4.7 to 6.9] micrograms/min; P < .05), fractional urinary albumin clearance (2.8 [1.6 to 4.8] x 10(-6) versus 1.3 [1.0 to 1.6] x 10(-6); P < .05), and TERalb (6.0 [5.5 to 6.5] versus 5.1 [4.5 to 5.8] %/h; P < .05) were higher in patients than in control subjects. Glomerular charge selectivity (ratio of IgG clearance to IgG4 clearance) was lower in patients than in control subjects (1.5 [1.1 to 2.0] versus 2.3 [2.0 to 2.6]; P < .05). These alterations were independent of blood pressure, glomerular filtration rate, tubular function, and smoking status. It is concluded that atherosclerotic vascular disease is associated with renal and systemic transvascular leakiness for albumin. Theoretically, such leakiness may in addition allow for an increased lipid insudation into the large vessel wall, thereby linking microalbuminuria to atherogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗
PubMed1993

Mycoplasma genitalium: a cause of male urethritis?

BACKGROUND: Male urethritis may be caused by mycoplasmas. Since Mycoplasma genitalium has previously been isolated from the urethra of two men with non-gonococcal urethritis (NGU), it was the aim of the study further to elucidate its role by measuring the prevalence of this organism in men with NGU. MATERIAL AND METHODS: The polymerase chain reaction was used. Two different sequences of the gene coding for the main adhesin MgPa were amplified. Urethral, rectal, and throat samples from 99 male sexually transmitted disease (STD) patients with and without urethritis were studied. RESULTS: M genitalium DNA was demonstrated in 17/99 (17%) of the urethral swabs, but in none of the rectal and throat swabs. Significantly more patients with urethritis (13/52) were positive for M genitalium DNA than were patients without urethritis (4/47) (p < 0.03). In those with urethritis M genitalium DNA was found more often in Chlamydia trachomatis negative NGU (12/34) than in those with chlamydial NGU (1/14) (p = 0.05). Attempts to culture M genitalium from the PCR positive specimens were unsuccessful. CONCLUSION: M genitalium DNA was found significantly more often in male STD patients with non-chlamydial NGU than in men with chlamydial urethritis (p = 0.05) and in men without urethritis (p = 0.003), suggesting that M genitalium may be a cause of NGU. M genitalium DNA was not demonstrated in any of the throat or rectal swabsindicating that the urogenital tract is probably the primary site of infection or colonisation of this species.

Base Sequence↗
PubMed1992

[Surgery of penile deviation by Ebbehøj's method].

A questionnaire investigation to evaluate the results of surgery for penile angulation by plicature of tunica albuginea by Ebbehøj's method is presented. In 31 patients with congenital penile angulation, 24 (77%) were satisfied with the functional result and 20 (65%) with the cosmetic result of the operation. In 14 patients with Peyronie's disease, eight (57%) were satisfied with the functional result and six (43%) with the cosmetic result of the operation. This is in accordance with previously published surveys of the results of surgery using this method. However, a high prevalence of late sequelae was observed, especially penile shortening and pain. In conclusion, the method yields acceptable functional and cosmetic results and is easy to perform. However, optimal surgical technique is imperative to reduce the prevalence of late sequelae which also necessitate detailed preoperative information and restrictive indications for surgery.

Adult↗
PubMed1992

[Treatment of superficial bladder tumors with intravesical BCG].

Thirty three patients with carcinoma in situ (CIS) or/and numerous recurrences of superficial bladder tumor were treated with intravesical BCG after transurethral resection. 63% of patients with CIS were free of recurrence after two years, two underwent cystectomy and one died because of progression. Patients with Ta and concomitant CIS responded well to BCG, while the patient with T1 tumor and CIS was free from recurrence for 15 months. Dysplasia of grade II disappeared after BCG. 62% of patients with Ta tumor were without recurrence after one year, but after two years 86% of the patients had recurrences. Patients with T1 tumor were free from recurrence for eight months, after which 25% had progression. The side effects of BCG were transient: urinary frequency in 48%, malaise in 39%, dysuria in 36%, haematuria, bladder pain and fever in 24%. 15% of the patients required isoniazid treatment. It is concluded that intravesical BCG is beneficial in CIS and superficial bladder tumors.

Administration, Intravesical↗
PubMed1992

Is diabetic nephropathy an inherited complication?

For yet unidentified reasons less than 50% of patients with insulin-dependent mellitus develop diabetic nephropathy. Genetic factors have been suggested as risk markers for development of nephropathy in diabetes. To further evaluate this hypothesis we studied the prevalence of nephropathy in diabetic siblings of diabetic patients with and without nephropathy. From a representative sample of 619 patients with insulin-dependent diabetes, we identified 20 patients with and 29 patients without nephropathy having diabetic siblings. Diabetic nephropathy (defined as urinary albumin excretion greater than 300 mg/24 hr) was found in 7 out of 21 siblings to patients with nephropathy and 3 out of 30 siblings to normoalbuminuric patients (P less than 0.04). No significant differences between the two groups of siblings with respect to age, diabetes duration, sex distribution, blood pressure or glycosylated hemoglobin A1c-levels were found. A significant correlation within sib-pair of glycosylated hemoglobin A1c was found (r = 0.47; P less than 0.001). We conclude that familial clustering of diabetic nephropathy does occur. This clustering may either be due to genetic inheritance or to sib-similarities due to shared environment, as indicated by the correlation of glycosylated hemoglobin A1c within sib-pairs.

Albuminuria↗
PubMed1992

Breathing zone concentrations of methylmethacrylate monomer during joint replacement operations.

By use of a methylmethacrylate (MMA) Dräger tube and bellow bump, the breathing zone concentrations of MMA monomer were measured for the operating surgeon during cementation of the components of hip and knee joint prostheses. The highest recordings (50-100 p.p.m.) were encountered during cementation of the acetabular cups with conventional polymethylmethacrylate cement. Such exposure could be eliminated by the use of personal protection equipment, local punctual field suction or change to a MMA/n-decylmethacrylate/isobornylmethacrylate bone cement.

Air Pollutants, Occupational↗
PubMed1992

Enzyme immunoassay for detection of immunoglobulin M (IgM) and IgG antibodies to Mycoplasma pneumoniae.

An enzyme immunoassay (EIA) for detection of immunoglobulin M (IgM) and IgG antibodies to Mycoplasma pneumoniae was developed. The EIA was evaluated on the basis of results in the M. pneumoniae complement fixation (MPCF) test and the cold agglutinin test. Serum samples from 430 patients with respiratory infections of known or unknown etiology, from 91 healthy children and adults and from 20 patients with rheumatoid factor, were investigated. By the criteria chosen for positive diagnostic EIA values, we found that the combined measurement of specific IgM and IgG gave a specificity of 99.7% and a sensitivity of 97.8%. If only IgM antibodies were measured, the specificity was 100% and the sensitivity was 88%. For IgG alone the specificity was 99.7%, but the sensitivity was only 46% because of the high EIA cutoff value chosen for IgG. We found no false positives among serum samples from patients with non-M. pneumoniae respiratory infection of known etiology, and there were no false IgM positives due to rheumatoid factor. In some cases the IgM EIA results became positive earlier in the course of illness than the MPCF titer. While children and teenagers responded predominantly with IgM antibodies, patients older than 40 years often had an IgG response only (56% of cases), probably because of reinfection. We conclude that this EIA is a good alternative to the combined MPCF and cold agglutinin tests in the diagnosis of M. pneumoniae infection.

Adolescent↗
PubMed1992

Unsatisfactory results after repeated revision of hip arthroplasty. 61 cases followed for 5 (1-10) years.

61 cemented second revision total hip arthroplasties and 18 cemented third revision total hip arthroplasties were studied with emphasis on causes of failure, complications, risk of further revision, and clinical and radiographic results of surviving, not further revised patients. Aseptic loosening was the major reason for both second and third revisions followed by recurrent dislocations. Of 61 second revisions, 21 failed again. Postoperative dislocation was the major complication, encountered in 10/61 after second revisions and in 4/18 third revisions. 10 second revisions were reoperated on without exchange of components, but for causes related to the implant. The clinical and radiographic outcome of surviving, not further revised patients was favorable, but must be seen in the light of the high rate of further revisions. In 33 of 53 second revisions and in 5 of 13 third revisions left for evaluation, the outcome was considered unsatisfactory. We conclude that reoperations for failed arthroplasties should be the prerogative of highly experienced centers.

Aged↗
PubMed1992

Mixing does not improve mechanical properties of all bone cements. Manual and centrifugation-vacuum mixing compared for 10 cement brands.

Contemporary mixing methods--centrifugation, vacuum mixing with or without precompression--were compared with manual mixing by testing strength characteristics in accordance with a proposed revision of the international standard for bone cements as applied to 10 cement brands. Simplex brands and low-viscosity cements were the strongest, and were not improved by any of the vacuum-mixing procedures. Centrifuging was found unsuitable for low-viscosity cements. Without attaining the strength of the former, the cements best suited for auxiliary mixing methods were CMW-1 and Palacos brands, which improved 6-11 percent by either of the methods. The Sterivac system was generally found unacceptable, because about 20 percent of a cement package was retained in the mixing gear, and the application of precompression had no additional effect on compressive and bending strengths.

Acrylic Resins↗
PubMed1992

The effect on cortical bone of reaming and filling of canine tibial diaphysis with inert bone wax.

In canine studies the effect of intramedullary reaming on tubular bone was investigated in 4 dogs. Intramedullary reaming was further compared with reaming and intramedullary filling with bone wax in 6 dogs. Bone blood perfusion was measured by a microsphere technique and bone remodelling activity by 99mTc-MDP uptake. From histological sections bone necrosis and remodelling activity were estimated. The biological response increased with the surgical trauma. If the medullary cavity was only reamed, endosteal apposition was the predominant reaction. Obturation of the medullary cavity resulted in more vigorous subperiosteal and cortical reaction. It is concluded that the remodelling processes differ significantly between reamed bone and bone where the medullary cavity is reamed and blocked. Thus when testing bone cement the studies should include a control operation with obturation of the medullary canal in a way simulating bone cement.

Animals↗
PubMed1991

Functional analysis of a specialized prey processing behavior: winnowing by surfperches (Teleostei: Embiotocidae).

Several surfperches (Embiotocidae), including the black surfperch, Embiotoca jacksoni, exhibit a specialized prey handling behavior known as winnowing, in which ingested food and non-nutritive debris are separated within the oropharyngeal cavity. Prey items are swallowed, and unpalatable material is ejected from the mouth. Winnowing is believed to play an important role in the partitioning of food resources among sympatric embiotocids. We present a mechanistic model for this separative prey processing based on high-speed video analysis, cineradiography, electromyography, and buccal and opercular cavity pressure transducer recording. Winnowing by embiotocids is characterized by premaxillary protrusions repeated cyclically with reduced oral gape. Protrusion is accompanied by depression of the hyoid apparatus and adduction of the opercula. Alternating expansion and contraction of the buccal and opercular cavities generate regular pressure waveforms that indicate bidirectional water flow during processing. Separation of food from debris by Embiotoca jacksoni occurs in three phases. The prey-debris bolus is transported anteriorly and posteriorly within the oropharyngeal cavity and is then sheared by the pharyngeal jaws. Mechanical processing is complemented by the rinsing action of water currents during hydraulic prey transport. The feeding apparatus of Embiotoca jacksoni is functionally versatile, although not obviously specialized relative to that of nonwinnowing surfperches. Protrusion of the premaxillae and depression of the hyoid apparatus are critical to both prey capture and subsequent prey processing. The pharyngeal jaws exhibit kinematic patterns during separation of food from debris distinct from those observed during mastication of uncontaminated prey. This behavioral flexibility facilitates resource partitioning and the coexistence of E. jacksoni in sympatric embiotocid assemblages.

Animals↗