Chemical and physical characterization of a novel poly(carbonate urea) urethane surface with protein crosslinker sites

A major complication which occurs with implantable polyurethane biomaterials is bioincompatibility between blood and the biomaterial surface. Development of a novel biodurable polyurethane surface to which biological agents, such as growth factors or anticoagulants could be covalently bound, would be beneficial. The purpose of this study was to synthesize a novel poly(carbonate urea) urethane polymer with carboxylic acid groups which would serve as "anchor" sites for protein attachment. Physical characteristics such as tensile strength, initial modulus, ultimate elongation, tear strength, water/alcohol uptake and water vapor permeation were then evaluated and compared to other biomedical-grade polyurethanes. Covalent linkage of the blood protein albumin to this novel surface was then examined. A biodurable polycarbonate-based polyurethane containing carboxylic acid groups (cPU) was synthesized using a two step procedure incorporating the chain extender 2,2-bis(hydroxymethyl)-propionic acid (DHMPA). Tensile strength of this cPU film was 2.7 and 2.6 fold greater than both a polycarbonate-based polyurethane synthesized with a 1,4-butanediol chain extender (bdPU) and Mitrathane (Mit) controls, respectively. The cPU polymer also possessed 7.8 and 31 fold greater structural rigidity upon evaluation of initial modulus as compared to the bdPU and Mit, respectively. Ultimate elongation for the bdPU films was slightly higher than the cPU and Mit films, which had comparable elongation properties. The force required to tear the bdPU film was 1.9 and 32 fold greater than the cPU and Mit films, respectively. Alcohol solution uptake by all of the polyurethane segments increased with increasing alcohol concentrations, with the cPU having the greatest uptake. Water uptake was minimal for all the polyurethanes examined and was not affected by altering pH. Water vapor permeation was lowest for the cPU films as compared to both bdPU and Mit. Swelling the cPU in 50% ethanol prior to evaluation slightly increased water vapor permeation through the films. Covalent linkage of the radiolabelled blood protein albumin (125I-BSA) to the cPU segments incubated with the heterobifunctional crosslinker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) was greatest in the higher percent of ethanol as compared to controls. These results serve as foundation for developing a novel poly(carbonate urea) urethane with physical characteristics comparable to other medical-grade polyurethanes while having protein binding capabilities.     

Genetic epidemiology of muscular dystrophies resulting from sarcoglycan gene mutations

BACKGROUND: The autosomal recessive limb-girdle muscular dystrophies (LGMDs) are a group of genetically heterogeneous muscle diseases characterised by progressive proximal limb muscle weakness. Six different loci have been mapped and pathogenetic mutations in the genes encoding the sarcoglycan complex components (alpha-, beta-, gamma-, and delta-sarcoglycan) have been documented. LGMD patients affected with primary "sarcoglycanopathies" are classified as LGMD2D, 2E, 2C, and 2F, respectively. METHODS: A geographical area in north east Italy (2,319,147 inhabitants) was selected for a genetic epidemiological study on primary sarcoglycanopathies. Within the period 1982 to 1996, all patients living in this region and diagnosed with muscular dystrophy were seen at our centre. Immunohistochemical and immunoblot screening for alpha-sarcoglycan protein deficiency was performed on all muscle biopsies from patients with a progressive muscular dystrophy of unknown aetiology and normal dystrophin. Sarcoglycan mutation analyses were conducted on all patient muscle biopsies shown to have complete or partial absence of alpha-sarcoglycan immunostaining or a decreased quantity of alpha-sarcoglycan protein on immunoblotting. RESULTS: Two hundred and four patient muscle biopsies were screened for alpha-sarcoglycan protein deficiency and 18 biopsies showed a deficiency. Pathogenetic mutations involving one gene for sarcoglycan complex components were identified in 13 patients: alpha-sarcoglycan in seven, beta-sarcoglycan in two, gamma-sarcoglycan in four, and none in the delta-sarcoglycan gene. The overall prevalence of primary sarcoglycanopathies, as of 31 December 1996, was estimated to be 5.6 x 10(-6) inhabitants. CONCLUSION: The prevalence rate estimated in this study is the first to be obtained after biochemical and molecular genetic screening for sarcoglycan defects.     

Traumatic aortic transections: eight-year experience with the "clamp-sew" technique

BACKGROUND: Because traumatic aortic transection is associated with high mortality rates, great debate exists about the appropriate operative technique for treatment of patients who have acute traumatic aortic transection. METHODS: To determine the safety and efficacy of the "clamp-sew" method, we retrospectively reviewed our 8-year experience treating 75 patients who had aortic injuries secondary to blunt trauma. Seventy-one of these patients were treated surgically. The clamp-sew method was used in all of these operations. RESULTS: Aortic cross-clamp time averaged 24 minutes (range, 14 to 36 minutes), with 4/71 having times in excess of 30 minutes. One patient (clamp time, 28 minutes) became paraplegic. Significant associated injuries were seen in 51/75 patients (48/71 patients with operation), including intrathoracic (35 patients), orthopedic (28 patients), intraabdominal (24 patients), and central nervous system (17 patients) damage. No patient died within 24 hours of operation. Overall 30-day mortality was 12% (9/75), with 7/9 having two or more aforementioned associated injuries. Of these 7, 5 had central nervous system injuries. Two of 9 died within 30 days without two or more associated injuries: 1 Jehovah's Witness of low hemoglobin, and 1 patient of sepsis. CONCLUSIONS: Although any of several maneuvers may be appropriate in managing traumatic aortic injuries, the simple "clamp-sew" technique is a safe and effective method for the treatment of traumatic aortic transections.     

Haldane's rule and X-chromosome size in Drosophila

The "dominance theory" of HALDANE'S rule postulates that hybrids of the heterogametic sex are more likely to be inviable or sterile than the homogametic sex because some of the epistatic incompatibilities contributing to postzygotic isolation behave as X-linked partial recessives. When this is true, pairs of taxa with relatively large X chromosomes should require less divergence time, on average, to produce HALDANE'S rule than pairs with smaller Xs. Similarly, if the dominance theory is correct and if the X chromosome evolves at a similar rate to the autosomes, the size of the X should not influence the rate at which homogametic hybrids become inviable or sterile. We use Drosophila data to examine both of these predictions. As expected under the dominance theory, pairs of taxa with large X chromosomes (approximately 40% of the nuclear genome) show HALDANE's rule for sterility at significantly smaller genetic distances than pairs with smaller X chromosomes (approximately 20% of the genome). As also predicted, the genetic distances between taxa that exhibit female inviability/sterility show no differences between "large X" vs. "small X" pairs. We present some simple mathematical models to relate these data to the dominance theory and alternative hypotheses involving faster evolution of the X vs. the autosomes and/or faster evolution of incompatibilities that produce male-specific vs. female-specific sterility. Although the data agree qualitatively with the predictions of the dominance theory, they depart significantly from the quantitative predictions of simple models of the dominance theory and the other hypotheses considered. These departures probably stem from the many simplifying assumptions needed to tractably model epistatic incompatibilities and to analyze heterogeneous data from many taxa.     

Wedge resection versus lobectomy for stage I (T1 N0 M0) non-small-cell lung cancer

BACKGROUND: The role of nonanatomic wedge resection in the management of stage I (T1 N0 M0) non-small-cell lung cancer continues to be debated against the present gold standard of care--anatomic lobectomy. METHODS: We analyzed the results of 219 consecutive patients with pathologic stage I (T1 N0 M0) non-small-cell lung cancer who underwent open wedge resection (n = 42), video-assisted wedge resection (n = 60), and lobectomy (n = 117) to assess morbidity, recurrence, and survival differences between these approaches. RESULTS: There were no differences among the three groups with regard to histologic tumor type. Analysis demonstrated the wedge resection groups to be significantly older and to have reduced pulmonary function despite a higher incidence of treatment for chronic obstructive pulmonary disease when compared with patients having lobectomy. The mean hospital stay was significantly less in the wedge resection groups. There were no operative deaths among patients having wedge resection; however, a 3% operative mortality occurred among patients having lobectomy (p = 0.20). Kaplan-Meier survival curves were nearly identical at 1 year (open wedge resection, 94%; video-assisted wedge resection, 95%; lobectomy, 91%). At 5 years survival was 58% for patients having open wedge resection, 65% for those having video-assisted wedge resection, and 70% for those having lobectomy. Log rank testing demonstrated significant differences between the survival curves during the 5-year period of study (p = 0.02). This difference was a result of a significantly greater non-cancer-related death rate by 5 years among patients having wedge resection (38% vs 18% for those having lobectomy; p = 0.014). CONCLUSION: Wedge resection, done by open thoracotomy or video-assisted techniques, appears to be a viable "compromise" surgical treatment of stage I (T1 N0 M0) non-small-cell lung cancer for patients with cardiopulmonary physiologic impairment. Because of the increased risk for local recurrence, anatomic lobectomy remains the surgical treatment of choice for patients with stage I non-small-cell lung cancer who have adequate physiologic reserve.     

Is life stress more likely to provoke depressive episodes in women than in men?

One of the most consistent findings in psychiatric research is that rates of major depression are at least twofold higher among women than among men. Although there is considerable agreement in the literature that life events play a role in producing, triggering, or maintaining episodes of depression, less is known about the relationship among gender, life events, and depression. In the present study, we compared the rates, focus ("interpersonal" vs. "non-interpersonal"), and timing of stressful life experiences reported in rigorous interviews of male and female patients with unipolar recurrent depression and nondepressed contrast subjects. Consistent with hypotheses, female patients were more likely to experience stressful life experiences than their male counterparts; rates of stressful life experiences did not differ between female and male controls. Unexpectedly, rates of interpersonal stress did not differ among males and females regardless of patient or control status. We also found no significant differences in the timing of pre-onset events: stressful events were generally concentrated in the period immediately preceding onset for both men and women. Thus, although these data suggest that life stress may play a larger role in the provocation of recurrent episodes of depression for women than for men, there do not seem to be sex differences in the extent to which interpersonal vs. noninterpersonal events and difficulties are associated with depression onset or in the temporal distribution of events. Implications of these results are discussed in the context of research on other putative factors contributing to gender differences in rates of depression.     

Some aspects of the lateralization of echoed sound in man. I. The classical interaural-delay based precedence effect

The precedence effect in two-click stimuli was investigated by measuring observers' sensitivity to interaural time delays (ITDs) as a function of interclick interval (ICI). A two-interval two-alternative forced-choice discrimination paradigm was used in two stimulus configurations: type I, a dichotic click with a given ITD preceded a diotic click; and type II, a dichotic click followed a diotic click. Threshold ITDs were measured in each configuration for a finely sampled distribution of ICIs that ranged from 0.1 to 25.6 ms. Performance was characterized by the "threshold elevation factor" (TEF) which normalized each of the observers' type I and type II ITD thresholds relative to their ITD threshold for a single dichotic click. The finer sampling of ICIs revealed two novel results: First, for two observers, sensitivity to ITD in the later arriving ITD (type II) oscillated in a consistent and systematic way with changes in ICI. Second, when the ICI reached 12.8 ms, ITD thresholds in the type I and type II configurations were equal but nearly a factor of 2 greater than for a single dichotic click. Some aspects of the data are consistent with the phenomenon of binaural adaptation.     

New gene assignments using a complete, characterized sheep-hamster somatic cell hybrid panel

OBJECTIVE: To assess the ability of the International Association for the Study of Pain Complex Regional Pain Syndrome (CRPS) diagnostic criteria and associated features to discriminate between CRPS patients and patients with painful diabetic neuropathy. DESIGN: Prospective assessment of signs and symptoms in a series of CRPS and diabetic neuropathy patients. SETTING: University of Washington Multidisciplinary Pain Center. PATIENTS: A consecutive series of 18 CRPS patients and 30 diabetic neuropathy patients. INTERVENTIONS: Patients completed a 10-item patient history questionnaire assessing symptoms of CRPS prior to medical evaluation. The evaluating physician completed a 10-item patient examination questionnaire assessing objective signs of CRPS. OUTCOME MEASURES: The analyses conducted were designed to test the ability of CRPS signs and symptoms and associated features to discriminate between CRPS patients and diabetic neuropathy patients. RESULTS: Data analysis suggested that CRPS decision rules may lead to overdiagnosis of the disorder. Diagnosis based on self-reported symptoms can be diagnostically useful in some circumstances. The addition of trophic tissue changes, range of motion changes, and "burning" quality of pain did not improve diagnostic accuracy, but the addition of motor neglect signs did. Test of a CRPS scoring system resulted in improved accuracy relative to current criteria and decision rules. CONCLUSIONS: Poorly understood disorders lacking prototypical signs/symptoms and diagnostic laboratory testing must rely on the development of reliable diagnostic guidelines. The results of this study should assist in the further refinement of the CRPS diagnostic criteria.     

Delivery of multiple CD8 cytotoxic T cell epitopes by DNA vaccination

Development of CD8 alphabeta CTL epitope-based vaccines requires an effective strategy capable of co-delivering large numbers of CTL epitopes. Here we describe a DNA plasmid encoding a polyepitope or "polytope" protein, which contained multiple contiguous minimal murine CTL epitopes. Mice vaccinated with this plasmid made MHC-restricted CTL responses to each of the epitopes, and protective CTL were demonstrated in recombinant vaccinia virus, influenza virus, and tumor challenge models. CTL responses generated by polytope DNA plasmid vaccination lasted for 1 yr, could be enhanced by co-delivering a gene for granulocyte-macrophage CSF, and appeared to be induced in the absence of CD4 T cell-mediated help. The ability to deliver large numbers of CTL epitopes using relatively small polytope constructs and DNA vaccination technology should find application in the design of human epitope-based CTL vaccines, in particular in vaccines against EBV, HIV, and certain cancers.     

Field cancerization: why late "recurrent" ovarian cancer is not recurrent

OBJECTIVE: Late "recurrence" of ovarian cancer may result from either regrowth of dormant tumor cells or from development of a new cancer caused by the phenomenon of field cancerization. Clinically, some recurrent ovarian cancers show the same therapeutic sensitivities to chemotherapy and surgery as did the primary disease, whereas others are refractory to all therapy. We hypothesize that recurrent ovarian cancers are distinguishable on the basis of a molecular genetic fingerprint and that some are actually new primary cancers of the peritoneum rather than recurrent ovarian cancer. STUDY DESIGN: We constructed molecular genetic fingerprints of 13 paired primary and late recurrent ovarian cancers to study their clonal relationships. The tumor pairs were analyzed for p53 mutations and allelotypes, patterns of X-chromosome inactivation, loss of heterozygosity, and microsatellite instability at 12 different loci on 6 different chromosomes. Techniques used included single-strand conformational polymorphism mutation screening and polymerase chain reaction-based sequence analysis of the p53 locus, restriction digestion of the androgen receptor locus to determine X-chromosome inactivation, and polyacrylamide gel electrophoresis of highly polymorphic dinucleotide, trinucleotide, and tetranucleotide repeats. RESULTS: The average age at initial diagnosis for this cohort was 54.7 years (range 45.3 to 65.5). Mean interval to recurrence was 42.7 months (range 28 to 62). Molecular fingerprints were characterized for 4 to 8 informative loci per tumor pair. The fingerprints of 10 (77%) differed significantly, strongly suggesting that a second primary cancer had developed. The remaining 3 tumor pairs demonstrated identical allelotypes consistent with regrowth of dormant tumor cells. CONCLUSION: Our results are consistent with the "field cancerization" hypothesis of ovarian carcinogenesis but could also be explained by a polyclonal tumor origin, which contrasts with the currently accepted monoclonal theory of ovarian carcinogenesis. Late development of a new primary cancer may herald the proband as a member of a familial cancer phenotype. These studies provide a molecular genetic rationale that both explains and prognosticates the clinical course of recurrent ovarian cancer.