Group-velocity-dispersion-compensated propagation of short pulses in dispersive media

An optical scheme based on a single angularly dispersive element is proposed for canceling group-velocity dispersion for pulse propagation in dispersive media. It is demonstrated experimentally that a pulse duration of 100 fs is preserved throughout the travel of a 248-nm-pulse through a 75-mm-long fused-silica slab.

Outdoor experimental ponds (mesocosms) designed for long-term ecotoxicological studies in aquatic environment

Outdoor artificial ponds (mesocosms) of 12 m3 were designed for long-term ecotoxicological studies. Sediment, macrophytes (Typha angustifolia and Elodea canadensis), and free and caged freshwater snails [Lymnaea palustris (Müller)] and wood lice (Asellus aquaticus L.) were collected in nearby natural ecosystems and introduced in the mesocosms. Sixty goldfish (Carassius auratus L.) were caged in each pond. Introduced species developed and reproduced in every mesocosm. Animal species (mainly insects and amphibians) spontaneously colonized the ponds, developed, and reproduced. The resulting communities qualitatively resemble those living in natural lentic systems in the surrounding area. Homogenity in physical and chemical conditions and in abundance of phytoplanktonic, periphytic, and macroinvertebrate communities between the different mesocosms was assessed during the stabilization period (8 months). Except for periphyton biomass, no divergent evolution was observed between the ponds. Mesocosm water was slightly eutrophic, alkaline (mean pH: 8.47 +/- 0.09), and moderately hard and mineralized. The homogenous and realistic environmental conditions and high ecological representativity of the outdoor experimental ponds were suitable for extensive ecotoxicological studies. Considerations on the choice and origin of introduced species and on possible interactive effects of the transfer of organisms from natural environments, maintainance conditions, and pollutant exposure are discussed.

Epidermal growth factor receptor and c-erbB-2 expression in normal breast tissue during the menstrual cycle

EGF receptor (EGF-R) and c-erbB-2 are homologous tyrosine kinase transmembrane receptors. They are involved in controlling proliferation, and probably differentiation, of normal breast epithelial cells, and their expression has been linked to the prognosis of breast cancer. Their physiological roles in normal breast tissue remain to be elucidated, as most studies to date have involved breast cancer cell lines. We studied the location of EGF-R and c-erbB-2 in 100 samples of normal breast with standard immunohistochemical methods and double-labelling techniques. EGF-R was mainly expressed on the stroma and myoepithelial cells, whereas c-erbB-2 expression was exclusively epithelial. An image analyser was used to quantitate variations in their expression during the menstrual cycle. EGF-R and c-erbB-2 expression on epithelial cells was stronger during the luteal phase than the follicular phase (p < 0.01 for EGF-R). The pattern of expression was also compared with that in 28 breast cancers and 7 fibroadenomas.

Autologous tissue cardiac valve for aortic valve replacement: technical aspects and early results

BACKGROUND

The known complications of heterograft bioprostheses and homograft valves have renewed the interest in the use of autologous material. A new technique to construct a tissue prosthesis for aortic valve replacement using the patient's pericardium harvested at the time of operation was developed. The glutaraldehyde-tanned pericardium is mounted on a stent requiring no suturing. Intraoperative testing assures adequate valve function.

METHODS

The autologous tissue cardiac valve was implanted in 50 patients in the aortic position between March 1994 and May 1995. Echocardiograms were performed in all patients before hospital discharge, at 3 months (41 patients), and at the end of first postoperative year (12 patients). The mean age was 69.8 +/- 5 years (range, 58 to 82 years). Eighty-four percent of patients presented with aortic stenosis and 16% had a combined lesion. Additional cardiac procedures were performed in 21 patients.

RESULTS

Aortic cross-clamp time was 72 +/- 19 minutes, and bypass time was 97 +/- 28 minutes. There were three in-hospital deaths, and 2 patients died within the first postoperative year. Predischarge echocardiography demonstrated excellent hemodynamics, with a mean gradient of 20 +/- 8 mm Hg and no or trivial aortic insufficiency in 45 patients. One patient had moderate aortic insufficiency. At first follow-up 36 patients (90%) were in New York Heart Association class I and 4 patients were in class II. Echocardiography showed no evidence of valve failure or degeneration (mean gradient, 17 +/- 5mm Hg; aortic insufficiency = grade 0 [trivial] in 35 patients, grade II in 3 patients, and grade III in 1 patient). Similarly, no degeneration or valve failure with increasing aortic insufficiency was seen in the patients studied at the end of the first postoperative year.

CONCLUSIONS

These results demonstrate that an autologous tissue cardiac valve can be manufactured in the operating room without significant additional operating time. Intraoperative testing minimizes the risk of primary failure with aortic insufficiency. Short-term results are encouraging with good hemodynamic performance of the valve and no signs of degeneration. However, long-term durability needs to be demonstrated.

Genotypes of the vitamin-D-receptor gene and bone mineral density in Caucasoid postmenopausal females

OBJECTIVE

To evaluate the relation of bone mineral density (BMD) to inherited polymorphisms within the gene coding for the vitamin D receptor (VDR) in postmenopausal women.

METHODS

DNA samples from 163 post-menopausal women and from 112 controls were genotyped for common allelic determinants within the VDR gene as defined by the restriction enzyme sites for BsmI, ApaI, and TaqI. BMD was evaluated at the lumbar spine (L2-L4) by dual energy X-ray absorptiometry. Single restriction enzyme site polymorphisms as well as their joint genotypes were evaluated for their association with BMD in postmenopausal women.

RESULTS

The three restriction site polymorphisms showed a close association indicating linkage disequilibrium (P < 0.0001). There was no relationship between any of the single restriction site polymorphisms and BMD. The distribution of the five most common joint genotypes among postmenopausal women and controls was similar. There was no relation of BMD and any of the five most common VDR genotype groups. Females more than 5 years after menopause had a significantly lower BMD than those less than 5 years after menopause (P < 0.001). This age-related decrease of BMD was also decernible within genotype groups.

CONCLUSION

In our population, the postmenopausal period has a major influence on BMD, but BMD is not controlled significantly by any of the common allelic variations within the VDR gene.

Capillary electrophoresis and supercritical chromatography, complementary and alternative techniques for the determination of urinary metabolites of styrene

Two analytical methods without an extraction step were developed using capillary electrophoresis and supercritical fluid chromatography in order to determine phenylglyoxylic (PGA) and mandelic (MA) acids in urine, with minimum treatment and manipulation of biological samples. The urine was diluted ten-fold in acetonitrile and directly injected into the analytical systems after centrifugation. Analysis was performed by capillary electrophoresis on alkyl bonded phase capillary columns with sodium formiate (4 x 10(-2) M)-isopropanol (9:1, v/v) as a buffer, and by supercritical fluid chromatography on a Diol bonded phase silica column with ethanol-water-methanesulphonic acid (97.5:2.4:0.1, v/v) as coeluent of CO2. Detection of PGA and MA was performed by ultraviolet detection at 255 and 210 nm, respectively. The methods are in agreement, and are easily able to detect 5 mg/g creatinine for PGA, and 15 mg/g creatinine for MA, which are one twentieth of the lowest biological exposure index values.

Evidence for recent growth of the HIV epidemic among African-American men and younger male cohorts in Los Angeles County

To estimate the recent course of the human immunodeficiency virus type 1 (HIV) epidemic among men within birth cohorts, ethnic groups, and HIV-risk groups in Los Angeles County, backcalculation methods were combined with log-linear models and census data to reconstruct HIV incidence in subgroups from AIDS surveillance data. Results were compared with directly measured HIV seroprevalence in public sexually transmitted disease (STD) clinics in Los Angeles. Models of HIV incidence indicate that the initial epidemic pattern among men who have sex with men, including a decline in incidence since the mid-1980s, does not apply to all post-1960 birth cohorts. Later peaks were observed in younger birth cohorts and among injection drug users, especially among African-American men, with no evidence of a peak before the 1990s among men born after 1960. Our results indicate that HIV continued to spread near peak rates into the 1990s among younger birth cohorts, especially among young African-American men who have sex with men. Because of the lengthy incubation period from HIV infection to AIDS incidence, our results imply that the AIDS epidemic has not yet peaked in these cohorts and may continue to grow through the present decade in several subgroups. The large variation in HIV incidence and prevalence across birth cohorts and other subgroups needs to be addressed in future community intervention plans.

Hybridization of 2,659 Clostridium perfringens isolates with gene probes for seven toxins (alpha, beta, epsilon, iota, theta, mu, and enterotoxin) and for sialidase

OBJECTIVE

To genetically characterize Clostridium perfringens isolates for association of pathologic type with various diseases.

DESIGN

Prospective study.

SAMPLE POPULATION

2,659 C perfringens isolates from various nonhuman animals species, human beings, and foods.

PROCEDURE

Colony hybridization with DNA probes for 7 toxin (alpha, beta, epsilon, iota (subunits a and b), theta, mu, and enterotoxin) genes and 1 sialidase gene were performed to group the isolates by pathologic type.

RESULTS

Enterotoxin-negative type-A isolates were the most common (2,575/2,659), were isolated from all sources, and were separated into 5 pathologic types. In cattle and horses with enterotoxemia, essentially only these pathologic types were identified. The enterotoxin-negative isolates of types C or D each had a single pathologic type. Type-C isolates were isolated only from swine with necrotic enteritis and type-D isolates from small ruminants with enterotoxemia, except that 1 type-D isolate was also found from a healthy fish. Type-B or -E isolates were not found. Among the 47 enterotoxin-positive isolates, 5 isolates from sheep or deer were type D and the other 42 were type A. These 42 isolates were grouped into 3 pathologic types: 1 type was isolated from samples of almost all origins, but the other 2 types were found in only 5 fish, 4 human beings, and 1 dog.

CONCLUSIONS AND CLINICAL RELEVANCE

Genetic characterization of these isolates allowed identification of 11 different pathologic types. This approach may be useful in molecular diagnosis and prophylaxis of clostridial disease.

[Use of centromedullar nailing as treatment in open tibial fractures stage IIIb in the tropics]

The authors report a retrospective study of 7 cases over a three-years-period. This study concerns patients treated in a tropical area in which the cutaneous tolerance of an external fixator is bad.Debridement was performed as an emergency without consideration of possible closure of the wounds. The bone was always covered at the end of the operation by a muscular pedicled flap.The fixation was performed by a reamed nail in 5 of the 7 cases.A primary consolidation was achieved in 58% of the cases.The mean time to consolidation was 7 months.

[Results of surgical treatment of metastases of renal carcinomas in 65 operated cases]

Several reports have assessed that the prognosis of metastatic renal cell carcinoma was better if patient's general condition was good, if primary tumor had been resected, if the time between nephrectomy and metastasis was long, if metastases are only pulmonary and bone marrow was not involved. The bone metastases of renal cell cancer have a bad reputation because of their haemorragic caracteristics and their resistance to radiotherapy.In the Orthopaedic and Traumatologic Department of the University hospital in Strasbourg, the authors had operated on 65 metastatic renal cell cancers. There were 55 patients (41 were men and 14 female), aged of 60 (range 41-84). Eight of them had 2 operations and 1 had 3 metastatic localisations.In 23% the metastases were present at the time of primary tumor diagnosis; in 17% the metastasis was even a signal metastasis. There were pathologic fractures in half of the cases (33 cases) and in the other half the metastasis had not fractured. The commonest site was the femur (40 of the 65 cases). The second site was the humerus (15 cases). There were also 7 vertebrae, 6 of them with neurologic deficit.The authors performed closed osteosynthesis in 27 cases (15 intramedullary nails, 7 Ender nails, 4 bipolar pinnings, 1 gamma nail), arthroplasty in 19 cases (6 standard prosthesis and 13 reconstruction prostheses) and an open osteosynthesis in 12 cases. They performed also 3 vertebrectomies by an anterior approach and 4 posterior decompressions and stabilisations.The average post operative survival was 15 months (range 0-109). Six patients died in the first post-operative month. Three non specific complications were observed: 2 prosthetic dislocations and one infected nail failure. 6 tumor extensions were observed on 2 prostheses, 3 intramedullary nails and 1 open osthesynthesis.The results were good for pain in 83% of the patients, the functional result good or fair in 78%.The efficacy of adjuvant medications was discussed, based on the literature data. Two groups of metastatic renal cell cancer were studied: the first with multiple metastases and a high speed progressive disease, the other with single metastasis and a low speed progressive disease. The surgical indications should be different in the two groups.

Loss of heterozygosity of the RB gene is a poor prognostic factor in patients with osteosarcoma

PURPOSE

The usual therapy of osteosarcoma is neoadjuvant chemotherapy, followed by surgery, then by postoperative chemotherapy. There is no prognostic factor to predict, at diagnosis, the histologic response and final outcome. Inactivation of the retinoblastoma-susceptibility gene RB is associated with the pathogenesis of several human cancers. In primary osteosarcomas, loss of heterozygosity (LOH) at the RB locus has been found in greater than 60% of cases. The aim of this study was to determine the potential early prognostic value of LOH of RB gene on the biopsy material at diagnosis.

PATIENTS AND METHODS

Forty-seven patients with primary osteosarcoma, treated in four French institutions, were studied. LOH was studied by polymerase chain reaction (PCR) of an informative RB DNA polymorphism.

RESULTS

Assessment of LOH at the RB gene could be completed on 34 heterozygous patients only. LOH was found in 24 cases (70%). The event-free survival (EFS) rate at 60 months is 100% for patients without LOH, 43% for all patients with RB LOH, and 65% for nonmetastatic patients with RB LOH. The difference in EFS is highly significant at P = .008 and P = .024, respectively. Histologic response after preoperative chemotherapy did not show significant correlation with LOH status.

CONCLUSION

RB gene LOH appears to be an early predictive feature for osteosarcomas that indicates a potential unfavorable outcome. RB LOH study might shortly help to identify high-risk patients earlier. If this is verified, therapy could then be adapted earlier to the individual's real risk of relapse.

[Clinical experience with a novel surgical technique: laparoscopy-assisted vaginal hysterectomy]

A new surgical technique, the laparoscopically assisted vaginal hysterectomy (LAVH) is evaluated through the clinical course of a group of patients operated for hysterectomy in the years 1993-1995. Although the groups of patients being operated for LAVH, vaginal or abdominal hysterectomy have not been randomized, we conclude that the laparoscopic assistance allows the vaginal approach of hysterectomies that should have been otherwise operated by laparotomy. Medical and financial advantages of this technique are discussed.

[Using fasciocutaneous flaps in open leg fractures stage III]

The use of pedicular fascio-cutaneous flaps to cover Gustilo III fractures of the leg is based on the vascular anastomotic system of the fascia. This system is provided by aterial branches from the deep muscles in the proximal third of the leg and by direct fascio-cutaneous branches in the distal third. The different fascio-cutaneous flaps are described with particular attention to specific indication in tibial fractures.

[Risk factors for acute hypersensitivity reactions in hemodialysis]

The aim of this prospective study was to evaluate the prevalence of anaphylactoid reactions (AR) in patients dialysed with cellulose or synthetic membranes and the possible link with ACE inhibitors. Survey was conducted for six months (Jan, 1 to July, 1 1993). Thirty dialysis units treating 1573 patients (899 M and 674 F) were participating to the study. At the end of the period under study, only 1536 patients were included in the analysis. Prevalence of AR was calculated from 122 694 hemodialysis sessions. Thirty-three AR in 21 patients (1.3%) (8 M, 13 F), of which 8 severe AR in 5 patients (0.25%) were observed. Annual incidence of AR was 0.17 per 1000 sessions with cellulose membranes and 4.2 per 1000 sessions with synthetic membranes. Relative risk of the occurrence of AR was 10 to 20 times higher with synthetic membranes than cellulose membranes, and 3 to 4 times higher in patient treated with ACE inhibitors than in those no treated. Prevalence of AR with AN69 membrane (3.2%) was not significatively different from that with other synthetic membranes (1.6%). However, treatment with ACE inhibitors increased strongly the risk of AR in AN69 patients (7.2%) in comparison to patients treated with other synthetic membranes (1.6%) ( < 0.1). Prevalence of severe AR was 0.25% in total dialysed population, 0.5% in patient treated with synthetic membranes, 1.1% in AN69 patient and 4.9% in AN69 patients treated with ACE inhibitors. Relative risk of AR is at least 20 times higher in dialysed patients with ACE inhibitors (1.7%) than other dialysed patients without ACE inhibitors (0%). Seventy-two percent of AR occurred in 2/30 dialysis units, thus demonstrating the role of a "un effect". That suggest the role of a "third factor" in the occurrence of AR.

[High grade osteosarcoma of the lower limb. Complications and results of the treatment of 20 patients]

Over 11 years we treated 30 osteosarcomas: 20 of them were high grade non metastatic osteosarcomas of the lower limb, which were treated by neoadjuvant chemotherapy (Rosen T10, or OS 87 protocol of the French Society for Pediatric Oncology).

MATERIAL AND METHODS

There were 12 males and 8 females; the mean age was 19 years (range 12-51). The site of the tumor was the femoral neck (1 case), femoral diaphysis (2 cases), distal femur (12 cases), proximal tibia (4 cases), distal tibia (1 case), 3 were IIA and 17 IIB according to Enneking system. Conservative treatment was performed in 17 cases: there were 12 knee prostheses, 4 allografts and 1 knee arthrodesis with allograft.

RESULTS

a) Surgical complications: Mechanical complications occurred in 10 patients. The function was preserved 8 times. In 2 patients the knee became stiff. An infection occurred in 3 patients: a conservative treatment was possible in 2 of them with a fair result. In the third case, an above-the-knee amputation had to be done. b) Functional results were studied according to Enneking rating. 14 arthroplasties (12 done as first surgical treatment and 2 after mechanical complication) had a 68, 19 score. c) Oncologic results: 8 patients were good respondents and 12 patients were bad respondents to chemotherapy according to Huvos grading. One local relapse was observed which could be treated by mean of a second chemotherapy and a prosthetic reconstruction. The patient is still alive and disease-free at 7 years (9 years after the diagnosis of the osteosarcoma). 5 patients had distant metastasis (lung, bones, and brain). One out of 5 was good respondent and 4 out of 5 are presently dead. Using Kaplan Meier statistical analysis, the overall survival wzs 76.8 per cent and the event-free survival was 67.4 per cent at 80 months.

CONCLUSION

We preferred a simple prosthetic reconstruction without osseous sleeve or an intercalary allograft if possible: these procedures allow the patient very rapid autonomy to have despite a prolonged chemotherapy.

Perioperative myocardial injury with different modes of antegrade and retrograde cardioplegic delivery

The effect of three cardioplegic protocols on perioperative myocardial injury was studied in 62 coronary artery bypass grafting (CABG) patients randomized into three groups with either antegrade or retrograde cold blood cardioplegia, or coronary sinus occlusion during antegrade supply. During the aortic cross-clamp time anterior and posterior septal temperatures were recorded, indicating the distribution of cardioplegic solution within the myocardium. Serum creatine kinase (CK), CK-isoenzyme MB and myoglobin as well as 12-lead electrocardiograms (ECG) were analyzed. Statistical analysis showed no effect of the cardioplegic protocol, whereas the patient's preoperative status, aortic cross-clamp time and intraoperative myocardial temperature had significant (P < 0.05) effects on immediate postoperative CK and CK-MB enzyme release. Creatine kinase-MB peak values were significantly increased in patients with major vessel disease and reduced left ventricular function (92 +/- 53 U/l versus 67 +/- 25 U/l). Both CK and CK-MB values were significantly higher in patients with aortic cross-clamp times of more than 1 h than in patients with shorter clamping times (661 +/- 188 and 78 +/- 40 U/l versus 500 +/- 200 and 57 +/- 24 U/l). Patients with 22 +/- 3 degrees C myocardial temperature before terminal cardioplegia had significantly elevated CK as compared to patients with temperatures of 15 +/- 2 degrees C (665 +/- 185 U/l versus 510 +/- 211 U/l). However, enzyme peak values had only poor predictive power for postoperative ECG changes, suggesting that enzyme peaks were not necessarily a sign of perioperative ischemia. Patients with major vessel disease and reduced myocardial function, with aortic cross-clamp time of more than 1 h and/or inadequate intraoperative myocardial cooling may be highly susceptible to global ischemia and operative procedures, and therefore show elevated peak enzyme levels shortly after surgery. In contrast, elevated myoglobin peaks within 1 h after aortic declamping were significantly correlated to perioperative signs of transient ischemia (P < 0.02).