Search PubMed⌕ Search

Biomedical subjects

R Langer

Publications and source records attributed to R Langer.

At least 451 records · Page 25Linked to original sources

[Abdominal sonographic findings in patients with AIDS].

The ultrasound findings of 58 patients with AIDS and ARC were analysed retrospectively. In 55% an enlarged liver, in 62% an enlarged spleen, partially with focal lesions, and in 21% enlarged abdominal lymph nodes were diagnosed. The typical focal segmental glomerulosclerosis of the kidney was observed in one case, and cholangitis in 2 patients. Abdominal ultrasound is the first diagnostic procedure to be performed in patients with AIDS and ARC when abdominal pathology is suspected. With US-guided thin needle puncture of the lesions, a histological verification of the pathologic findings is possible.

Abdomen↗

[Diagnostic strategies in liver and pancreatic tumors using imaging procedures--nuclear medicine].

The different biokinetic behaviour of radioactive tracers which can be monitored by nuclear medicine procedures may be helpful in the diagnosis or differential diagnosis of tumours or tumour-like lesions of the liver or pancreas: autologous red blood cells in the detection of haemangiomas; iminodiacetates in delineation of focal nodular hyperplasia, resp. liver adenomas versus other tumours; colloidal albumin in differentiating focal fatty infiltration from diffuse infiltration by metastases; monoclonal antibodies in revealing liver metastases or abscesses, resp. pancreas neoplasms. In general the clinical suspected diagnosis and the result of morphologic imaging modalities determine the use of the appropriate radioactive tracers.

Adenoma↗

[Postoperative computed tomography control of allogeneic vascular prostheses].

33 CT-studies of 26 patients with alloplastic vascular prostheses were evaluated and compared with postoperative digital subtraction-angiography in 16 cases. 13 patients had no pathologic findings confirmed by further clinical development. In 4 cases bypass infection was diagnosed, which CT findings were perigraft gas (2/4), perigraft fluid (4/4), cm-enhancement (4/4) and fistulas (2/4). 10-21 d. post.-op. sterile hematomas were found in 3 patients. Further 3 cases had 5 weeks-2 post.-op. perigraft seromas. CT was method of first choice for diagnostic of perivascular alterations after bypass surgery. DSA was complementary to CT and should be performed to detect vascular complications.

Aged↗

The effect of total abdominal hysterectomy on bladder function in asymptomatic women.

The effect of total abdominal hysterectomy as treatment for benign conditions on the postoperative incidence of urinary symptoms and abnormal urodynamic findings was evaluated in 16 premenopausal women who lacked urinary symptoms preoperatively. The urodynamic evaluation was performed preoperatively, at 4 weeks, and again at 4 months after surgery. No clinical symptoms of frequency, nocturia, urgency, or urge or stress incontinence were found postoperatively. There were no significant differences from the preoperative values for cystometry, uroflometry, and urethral pressure profiles. Urinary dysfunction should not be a consequence of an uncomplicated total abdominal hysterectomy for benign conditions in women who were previously free of urinary symptoms.

Adult↗

Polyanhydride microsphere formulation by solvent extraction.

A novel process based on solvent extraction was developed to produce drug-loaded polyanhydride microspheres for controlled-release applications. The technique consists of adding a chloroform solution of polyanhydride and drug into a stirred silicone oil phase containing suspended droplets of surfactant. No chemical reaction, heating, nor contact with water was required in this process. The microspheres produced were capable of releasing various dyes for prolonged periods of time.

Anhydrides↗

[Experimental ultrasonic study of imaging of vascular implants].

An experimental in vitro study was performed, evaluating 13 bypasses and eight patches of different materials. Sonography was unsuccessful due to a total reflection of the ultrasound for the PTFE-Vitagraft, the Impra, and the Microvel Haemashield bypasses. All other studied bypass types were successfully evaluated by ultrasound. All studied patch materials did not interfere with the ultrasound examination of the vascular structures.

Blood Vessel Prosthesis↗

Selective cell transplantation using bioabsorbable artificial polymers as matrices.

To date, selective cell transplantation has involved injecting cell suspensions into tissues or the vascular system. This study describes attaching cell preparations to bioerodable artificial polymers in cell culture and then implanting this polymer-cell scaffold into animals. Using standard techniques of cell harvest, single cells and clusters of fetal and adult rat and mouse hepatocytes, pancreatic islet cells, and small intestinal cells have been seeded onto biodegradable polymers of polyglactin 910, polyanhydrides, and polyorthoester. Sixty-five fetuses and 14 adult animals served as donors. One hundred fifteen polymer scaffolds were implanted into 70 recipient animals: 66 seeded with hepatocytes; 23 with intestinal cells and clusters; and 26 with pancreatic islet preparations. The cells remained viable in culture, and in the case of fetal intestine and fetal hepatocytes, appeared to proliferate while on the polymer. After four days in culture, the cell-polymer scaffolds were implanted into host animals, either in the omentum, the interscapular fat pad, or the mesentery. In three cases of fetal intestinal implantation coupled with partial hepatectomy, successful engraftment occurred in the omentum, one forming a visible 6.0 mm cyst. Three cases of hepatocyte implantation, one using adult cells and two using fetal cells, have also engrafted, showing viability of hepatocytes, mitotic figures, and vascularization of the cell mass. To date, no pancreatic islets have survived implantation. This method of cell transplantation, which we have termed "chimeric neomorphogenesis," is an alternative to current methods and requires further study.

Animals↗

[Sonographic assessment of vascular bypasses in vitro].

13 bypasses and 8 patches were examined by ultrasound in vitro with a 3.5 MHz and a 10 MHz probe. Whereas only 6 bypasses were assessable by sonography, all patches could be demonstrated in vitro. In these cases, sonography could be accomplished with either of the two frequencies used. The 10 MHz probe was superior for imaging structural details. Immediate postoperative sonography of such grafts, which cannot be demonstrated accurately in vitro, is not reliable.

Blood Vessel Prosthesis↗

Ex vivo model of an immobilized-enzyme reactor.

Immobilized-enzyme reactors are beginning to be studied for a variety of therapeutic applications. To facilitate the design of these devices for different clinical situations and a diverse patient population, mathematical models may be valuable. An immobilized-heparinase (EC 4.2.2.7) reactor was selected as a model system. The device removes heparin from blood that has been anticoagulated to prevent thrombus formation. Heparinase was immobilized to cross-linked agarose particles. A mathematical model was developed to describe the clearance of heparin by the reactor ex vivo and compared to experimental clearances measured in sheep. The model accounted for enzymatic degradation as well as the binding of heparin and its breakdown products to antithrombin. The device was modeled as a steady-state continuously stirred tank reactor. Molar conservation equations within the agarose particles accounted for simultaneous diffusion and chemical reaction. The model had no adjustable parameters and was able to predict the clearance of heparin within 5-25% for three different animals and 12 different perfusions.

Animals↗

Enzymatically controlled drug delivery.

An approach for providing feedback control for polypeptide drugs in a polymeric controlled-release system uses a trigger molecule and a polymer-bound enzyme that, in the presence of that trigger molecule, will cause an acid or a base to form. When the pH inside the polymer system changes, the solubility of the drug shifts dramatically, which changes the diffusion or dissolution driving force, and hence the release rate changes correspondingly. This concept was tested using a controlled-release system of ethylene/vinyl acetate copolymer containing insulin and immobilized glucose oxidase. The enzymatic reaction of glucose to gluconic acid reduces the pH in the polymer microenvironment. Since insulin solubility increases with decreasing pH (at physiologic pH, this is true for an insulin with an isoelectric point of 7.4 or higher), the release of insulin increases in response to glucose concentration. The feasibility of this concept has been shown using trilysyl insulin with an isoelectric point of 7.4. Multiple exposures to buffered glucose solutions over several weeks caused insulin release to reversibly increase during each exposure. Polymer-implanted diabetic rats infused with glucose solutions showed a significant increase in insulin concentration in 30 min-an effect not observed in three different sets of control rats.

Animals↗

The value of simultaneous hysterectomy during Burch colposuspension for urinary stress incontinence.

The effect of concomitant hysterectomy during colposuspension on the cure rate of genuine stress incontinence was evaluated prospectively in 45 patients. Twenty-two women underwent a colposuspension only (no-hysterectomy group) and 23 had a concomitant abdominal hysterectomy and cul-de-sac obliteration (hysterectomy group). Twenty-five months postoperatively, no differences were found in the cure rate for urinary stress incontinence between the two groups (95.5 and 95.7% for the no-hysterectomy and the hysterectomy group, respectively). In the no-hysterectomy group, three patients (13.6%) had enterocele formation after surgery; this complication did not occur in any of the patients in the hysterectomy group.

Female↗

Detrusor instability following colposuspension for urinary stress incontinence.

Sixty-two patients with genuine stress incontinence (group A) and 30 women with combined detrusor instability and genuine stress incontinence (group B) had a colposuspension operation. The proportion with symptoms of detrusor instability was significantly reduced from 24% before operation to 9% after operation in group A and from 73% to 33% in group B. Urodynamically, detrusor instability developed after surgery in 17 of the 62 patients (27%) in group A whereas only 12 of the 30 women (40%) in group B had detrusor instability after surgery. No urodynamic explanation was found to explain the effect of colposuspension in relieving the symptoms of detrusor instability in some and causing them in others. Nevertheless, it is suggested that colposuspension is helpful for most patients with combined detrusor instability and genuine stress incontinence.

Adult↗

Transdermal delivery of drugs.

Transdermal drug delivery involves the continuous administration of therapeutic molecules through the skin. It has the advantage of maintaining constant drug plasma levels and improving patient compliance. Compared to the oral route, losses in bioavailability due to first-pass liver metabolism are reduced. This paper describes the theory of transdermal drug penetration, the role of the skin, in vitro testing, examination of currently available transdermal delivery systems, and recent developments in iontophoresis, prodrugs, and penetration enhancers.

Administration, Cutaneous↗

Colposuspension in patients with combined stress incontinence and detrusor instability.

Thirty women with combined urinary stress incontinence and detrusor instability were treated by a colposuspension operation for urinary incontinence. Following surgery we found a significant reduction of symptoms regarding detrusor instability, from 22/30 patients preoperatively (73.3%) to 10/30 patients (33.3%). Urodynamically, 40% of the patients had detrusor instability following surgery. Only one surgical failure was encountered (3.3%). It is suggested that patients with combined detrusor instability and stress incontinence should be operated on. This group of patients was cured as far as stress incontinence is considered, and 60% of the patients presented normal cystometric findings and more than 50% of the patients (12/22) greatly improved clinically, regarding symptoms of detrusor instability, following surgery.

Adult↗