Biomedical subjects
Publications and source records attributed to R Langer.
Comparative radiologic/pathologic study of 45 newborns with primary and secondary pulmonary hypoplasia. 43 cases were proven at autopsy. From 9 cases with primary pulmonary hypoplasia, 7 could be identified by 3 independent observers. The roentgen criteria of primary pulmonary hypoplasia are evaluated and should serve in the future to clinically diagnose this condition.
Report of the 10th case of infantile cortical hyperostosis (ICH), diagnosed in utero. Because of a hydramnion noted in the 29th week of gestation, a 38 years old pregnant women was admitted to hospital. Ultrasound, radiographs of the unborn child and amninography were obtained. The radiographic and clinical signs of Caffey's disease are reviewed, and the literature particularly reports on prenatal onset are analyzed. The present "etiologic theories" are discussed.
PURPOSE: The purpose of our study was to evaluate the relevance of MR mammography in the diagnosis of early and late tumor recurrence after breast-conserving therapy. METHOD: Sixty-seven patients receiving breast-conserving therapy underwent 84 MR mammographies in a period between 1 month and 14 years after end of therapy. Dynamic measurements were made following application of contrast agent. The course of signal intensity changes was evaluated in focal lesions and irradiated and contralateral glandular tissue. RESULTS: All 10 malignant lesions (7 local recurrences, 1 chest wall recurrence, 2 contralateral carcinomas) showed a > 75% increase in signal intensity within th first minute after contrast agent application. In all patients examined during the first year after end of therapy (n = 29), increased enhancement in irradiated parenchyma was observed compared with the contralateral breast, but only in two patients the increase was > 75% within the first minute. CONCLUSION: Already in the first year after end of therapy, MRI can improve diagnostic accuracy in the assessment of breast cancer recurrence. More than 12 months following end of therapy, MR mammography can demonstrate tumor recurrence with a sensitivity of nearly 100% and a specificity rising to > 90% in differentiating tumor from therapy-induced changes.
Engineering new tissues by transplanting cells on polymeric delivery devices is one approach to alleviate the vast shortage of donor tissue. However, it will be necessary to fabricate cell delivery devices that deliver cells to a given location and promote the formation of specific tissue structures from the transplanted cells and the host tissue. This report describes the design and fabrication of a polymeric device for guiding the development of tubular vascularized tissues, which may be useful for engineering a variety of tissues including intestine, blood vessels, tracheas, and ureters. Porous films of poly (D, L-lactic-co-glycolic acid) have been formed and fabricated into tubes capable of resisting compressional forces in vitro and in vivo. These devices promote the ingrowth of fibrovascular tissue following implantation into recipient animals, resulting in a vascularized, tubular tissue. To investigate the utility of these devices as cell delivery devices, enterocytes (intestinal epithelial cells) were seeded onto the devices in vitro. Enterocytes were found to attach to these devices and form an organized epithelial cell layer. These results suggest that these devices may be an appropriate delivery vehicle for transplanting cells and engineering new tubular tissues.
The small bowel mesentery provides a unique structure of a large vascularized surface area to support hepatocyte transplantation. Cell-seeded polymeric matrices can be juxtaposed in a relatively atraumatic manner between leaves of mesentery such that adequate exchange of nutrients and diffusion of gases can proceed in the interim while neovascularization occurs. Hepatocytes obtained from (RHA) Wistar rats by collagenase perfusion were seeded onto non-woven filamentous sheets of polyglycolic acid 1 x 3 cm in size and 2 mm thickness to a density of 500,000 cells/cm2. Twenty-six recipient Gunn rats (UDP-glucuronyl transferase deficient) underwent laparotomy. Hepatocyte-ladened polymer sheets were placed between leaves of mesentery. Eight sheets were placed per animal and the leaves were approximated, creating a functional implant 1 x 3 x 2 cm. Biopsies between 5-99 days after implantation revealed neovascularization, moderate inflammatory reaction and the presence of viable hepatocytes in 96% (25/26). Immunoperoxidase studies using anti-albumin antibody substantiated hepatocyte specific function in implants. HPLC profiles of bile from Gunn rats transplanted with hepatocytes from congeneic (RHA) rats demonstrated the presence of bilirubin conjugates. There were no conjugation fractions seen in control gunn rats without hepatocyte transplantation. Although total serum bilirubin did not significantly decrease, conjugated bilirubin was identified in 46% (12/26) animals after transplantation with congeneic hepatocytes. We conclude that the mesentery of the small bowel provides a large vascularized surface for cell transplantation. Large numbers of metabolically active hepatocytes can engraft, vascularize, and show function. The mesentery may be a potential bed for clinical hepatocyte transplantation.
We have investigated and quantified the degree of fibrovascular tissue ingrowth in cylindrical poly(vinyl alcohol) (PVA) foams of 12.5 mm diameter, 5 mm thickness, and 71% porosity implanted in the mesentery of rats over a period of 25 days. Fibrovascular tissue penetrated the center of PVA foams 5 days postimplantation yet the void fraction available for cell seeding was 55% and the volume average pore diameter was 190 (+/- 39) microns. By 10 days postimplantation the void fraction had decreased to 32% and the volume average pore diameter was 121 (+/- 20) microns. As time elapsed fibrovascular tissue continued to expand and fill the remaining pore space. At 15 days postimplantation the void space was impractical for cell seeding and continued to decrease through the remainder of the study. Our data suggest that hydrogel foams with a polydispersed pore morphology can be prevascularized with adequate space for cell seeding as the volume of tissue penetrating the foam is limited by the smaller pores in the foam structure; however, available void space for cell seeding decreases with time.
The progress toward the development of a single dose tetanus vaccine has been limited by the poor stability of the protein antigen, tetanus toxoid (TT), during its encapsulation in, and release from, biodegradable polymer microspheres. To investigate alternative microencapsulation approaches that may improve the stability of TT under these conditions, a two-step microencapsulation method has been devised to form microcapsules which consist of: (a) forming microcores of TT in a hydrophilic support matrix by spray-congealing, followed by (b) coating the microcores with poly(lactide-co-glycolide) (PLGA) by an oil-in-oil solvent extraction method. Several protein stabilizers including gelatin (with or without poloxamer 188), dextran, sodium glutamate, and polyethylene glycol were examined as potential core-materials. Among them, gelatin was superior in its ability to impart stability to TT against heat and moisture-induced inactivation. Microcores of this latter stabilizer and TT were encapsulated in PLGA using the foregoing technique, which exposed the dry antigen to minimal water in order to prevent its irreversible inactivation during exposure to the organic solvent. The microencapsulation method resulted in minimal loss of antigenically active TT (approximately 10-20%). Microscopic analysis of the microcapsules following preparation showed the microcores to be fully encapsulated. However, microcapsules containing TT and gelatin released the active antigen nearly completely within one day. Fluorescence confocal microscopy revealed that the swelling of the hydrophilic core-material was responsible for the burst-release behaviour. Manipulation of the polymer coating could not slow down this 'explosion' of the microcapsules. TT-containing PLGA microcapsules have been prepared using a novel microencapsulation method, which retains an extremely high fraction of antigenically active TT. Hence, these mechanistic approaches may be useful in the development of effective single-dose vaccines.
BACKGROUND: Fallopian tube torsion is a cause for acute low abdominal pain that is difficult to diagnose. The purpose of this article is to review the available data on and to update clinicians regarding its diagnosis and treatment in the era of laparoscopic surgery. METHODS: We searched in MEDLINE and EMBASE and reviewed the lists of references. The keywords used were "laparoscopy," "fallopian tube," and "torsion." RESULTS AND CONCLUSION: Fallopian tube torsion is an uncommon cause for acute low abdominal pain in women. Because it has no pathognomonic clinical symptoms or findings on imaging or laboratory studies, a history of current or past pelvic pathologic conditions or surgery, as well as pregnancy, should draw the attention of the attending physician to its occurrence. Early laparoscopy is the reference standard in the diagnosis and treatment.
For three consecutive years, beginning in 1986, we evaluated cardiovascular disease (CVD) risk factors of medical students as part of the teaching program in a Preventive Cardiology Academic Award. Entering students in three consecutive classes were screened on the first day of orientation to medical school. The first year, we evaluated 108 students (71 men and 37 women), the second year, 99 students (75 men, 24 women), and the third year 108 students (67 men and 41 women). During the single four-hour period, we obtained data on personal and family history of CVD risk factors, type A behavior, knowledge of CVD, attitudes toward CVD prevention, measures of depression and anger, blood pressure, blood pressure reactivity, physical activity, and diet. Blood was drawn for lipid analysis. Height and weight were measured, and a physical fitness step test was administered. Pulmonary function was measured during the third year. We used a four-tiered approach to preventive cardiology education. During the assessment session, abnormalities, such as elevated blood pressure or abnormal pulse, were discussed with the student. In the second tier, the data were analyzed and returned to all students during teaching sessions, enabling them to compare their levels with the class and the national averages. For the third tier, students with high-risk values, defined as low-density lipoprotein cholesterol level > or = 150 mg/dL, a total cholesterol or triglyceride level > or = 200 mg/dL, or blood pressure > or = 140/90 mmHg, were seen by faculty physicians who suggested remedial interventions in separate sessions.(ABSTRACT TRUNCATED AT 250 WORDS)
The purpose of this study was to obtain directional angiogenesis of small blood vessels and capillaries to an implant made from a resorbable polymer for hepatocyte transplantation. It was intended to mimic the native acinar structure of the liver in form to facilitate replication of the cells and organ growth. The implant device structure was designed for injection to minimize surgical trauma. Hollow microspheres with an open porous wall structure and one large central opening were made from poly(d,1-lactic-co-glycolic acid) (85:15 lactic:glycolic). This polymeric scaffold was seeded with hepatocytes and implanted into the abdominal wall muscle of syngeneic Fisher rats. Specimens explanted up to 56 days postoperatively showed hepatocyte survival and the development of a directional blood supply, a phenomenon known as "angiopolarity." This study should help in addressing the issue as to whether vascular cell implants with posttransplantation organ growth should be attempted.
Twenty-nine cases of cervical incompetence were found among 98 women diagnosed as having a congenital uterine anomaly on hysterosalpingography, a high incidence of 30%. The highest incidence was found in the bicornuate uterus group--38%. The incidence of premature delivery and late abortion was higher in this group than in the rest of the patients with uterine anomalies (55% and 68%, vs. 45% and 32%). An obvious improvement in obstetrical performance was noted after cerclage. In the cervical incompetence group, term deliveries increased from 26% to 63%. Premature deliveries and late abortions dropped from 74% to 37%. Even in the patients with anomalous uterus without proven diagnosis of cervical incompetence, term deliveries increased from 64% to 96%, and pregnancies terminating prematurely dropped from 35.6% to 4%, following cerclage. No doubt exists as to the need for cerclage in cases of cervical incompetence. We also believe it should be performed prophylactically in cases of bicornuate uterus. The concept of routine prophylactic cerclage in all cases of uterine anomalies should be considered.
Our study includes 15 posttransplant angiographies in 10 patients after liver transplantation and 3 cases with embolisation of the splenic artery because of a splenohepatic steal syndrome. The results of the angiographies are demonstrated and discussed. In cases with non-conclusive ultrasound or CT findings, angiography is the method of choice, if an arterial anastomotic complication or a chronical rejection is suspected.
Eleven patients after liver transplantation underwent 17 radiological interventions. Most of the cases were encapsulated fluid collections with episodes of fever. Radiological interventions make re-operations unnecessary in the majority of the cases. Our data are compared with those of other publications.
Regional cerebral blood flow (rCBF) was evaluated quantitatively by 99mTc hexamethyl propyleneamine oxime and single photon emission CT (SPECT) during the interictal phase in 52 patients with focal epilepsy. The results were compared with those obtained by electroencephalography (EEG), CT, and magnetic resonance (MR) imaging. Twenty-four of the 52 patients had one area of local hypoperfusion whereas 7 patients showed an area of local hyperperfusion. In 20 of the 52 patients, both reduced and elevated rCBF values were found. One patient had a normal perfusion pattern. The SPECT findings correlated well with the foci shown by EEG, both with regard to the sides affected and the locations of the regions of altered perfusion. The MR images showed focal lesions in only approximately one-half of the patients examined, and CT in even fewer.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Two model enzymes, heparinase and bilirubin oxidase, were immobilized via cyanogen bromide, tresyl chloride, epoxide, or carbodiimidazole activated natural and synthetic matrices. The supports released enzymes for 4-20 hr in vitro at 37 degrees C. The most stable linkage was formed by tresyl chloride and oxirane activated supports. No immune response was detected 11 or 21 days after single i.v. injection to New Zealand white rabbits. Acute exposure to the enzyme produced a weak positive response.