Double-crowned valved stents for off-pump mitral valve replacement.

OBJECTIVE: An animal model has been designed to assess the feasibility of off-pump mitral valve replacement using valved stents. METHODS: Glutaraldehyde-preserved homograft was sutured inside a prosthetic tube (Dacron). Then, two self-expandable nitinol Z-stents were sutured on the external surface of the prosthesis in such a way to create two self-expanding crowns for fixation. In adult pigs and under general anesthesia, the left atrium was exposed through a left thoracotomy and atrio-ventricular roadmapping was performed with intravascular ultrasound (IVUS) and fluoroscopy. The double-crowned valved stents were loaded into a delivery sheath. The sheath was then introduced into the left atrium and the valved stents was deployed in mitral position in such a way that the part in between the two stents was at the level of the mitral annulus. Intracardiac Unltrasound (ICUS) was used to assess the valve function. Hemodynamic parameters were gathered as well. Animal survived for no more than 3h after the valve deployment and gross anatomy examination of the left heart was carried out. RESULTS: The mean height of the valved stents was 29.4+/-0.2 mm, with an internal diameter of 20.4+/-1.0mm, and an external diameter of 25.5+/-0.8 mm. The procedure was successfully carried out in eight animals. In vivo evaluation showed a native mitral annulus diameter of 24.9+/-0.6 mm, and a mean mitral valve area of 421.4+/-17.5 mm2. ICUS showed a mild mitral regurgitation in three out of eight animals. Mean pressure gradient across the valved stents was 2.6+/-3.1 mmHg. Mean pressure gradient across the left ventricular outflow tract (LVOT) was 6.6+/-5.2 mmHg. The mean survival time was 97.5+/-56.3 min (survival time range was 40-180 min). One animal died due to the occlusion of the LVOT because of valved stents displacement. Postmortem evaluation confirmed correct positioning of the valved stent in the mitral position in seven out of eight animals. No atrial or ventricular lesions due to the valved stents were found. CONCLUSIONS: Off-pump implantation of a self-expandable valved stent in the mitral position is technically feasible. Further studies will assess if this procedure is also feasible in humans.     

Evaluation of postsurgical crestal bone levels adjacent to non‐submerged dental implants

In most of the studies on long-term radiographic evaluations of crestal bone levels adjacent to dental implants, no baseline radiographs taken immediately post-surgically had been obtained.The aim of this study was to test the reproducibility of a simple radiographic method for linear measurements of changes in bone levels and to evaluate changes in crestal bone levels adjacent co non-submerged ITI® implants 1 year following the surgical procedure. From 128 patients enrolled in a clinical and radiographic longitudinal study 40 patients also had radiographs taken immediately postsurgically. They were, however, not obtained as “identical” images. The radiographs were mounted onto slides and projected on a screen. Mesially and distally from 57 implants triplicate linear measurements of the distance implant shoulder to bone crest were taken, using known dimensions of the implants as internal reference distances. The median difference of 213 (out of 228 possible) duplicate measurements was 0.00 mm (ranging from ?1.72 mm to +1.47 mm when comparing the second co the third reading). Some 81% of the double measurements were within ±0.5 mm and the precision was 0.30 mm. In the immediate postoperative radiographs the median mesial bone level was located at 2.07 mm (distally 2.19 mm) from the implant shoulder. A statistically significant amount of bone loss in the first year was observed mesially (median=?0.78 mm) and distally (0.85 mm)(Wilcoxon matched pairs signed rank test ±0.001). No statistically significant influence of the implant location, the implant length, type of the implant (screw; cylinder) was observed (Kruskal-Wallis P>0.05).The age of the patients was not correlated significantly to the amount of bone loss observed. In conclusion, methodological limitations existed when evaluating linear bone changes in non-identical radiographs using reference dimensions of the implants. The amount of postsurgical bone loss estimated in other studies was confirmed when using an immediate postoperative radiograph as a baseline.     

Hepatic resections for metastases]

Between January 1981 and December 1990, 79 liver resections were performed for hepatic metastases in 73 patients. Eight of these patients had a repeat resection (2 patients had their first resection performed before 1981). This figure represented 35% of 228 liver resections performed during this period. Mean age was 56.5 years (23 to 81 years). There were 38 men and 35 women. Fifty-four resections were performed for colorectal metastases and 25 resections for secondaries of other origins. There were 45 major hepatectomies (57%), defined by the resection of at least 3 Couinaud segments, and 34 minor resections (less than three segments). In 12 patients, liver resection was associated with excision of the primary tumor. Complications were observed in 25 patients (32%), pulmonary complications being the most frequent. Five re-explorations were necessary: 3 for postoperative bleeding, one for an abdominal abscess and one for intestinal obstruction. Mean postoperative stay was 18 days. There was no mortality for the first liver resections in 71 patients. One death was encountered among the second resections in 8 patients, with a global mortality of 1.3%. Follow-up was obtained for all patients but one (lost to follow-up at 5 years). Actuarial survival for the 50 patients operated on for colorectal secondaries was 98% at 6 months, 83% at 1 year, 46% at 2 years, 24% at 3 years and 15% at 5 years. In non-colorectal secondaries, the survival depended on the nature of the primary tumor but was very different from one patient to another.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hypothyroidism and hyperprolactinemia as a possible cause of androgenetic alopecia in the female

31 female patients suffering from androgentic alopecia were examined by means of the TRH test with regard to hypothyroidism and hyperprolactinemia. Before, as well as 20 and 40 minutes after, application of thyroxine releasing hormone (TRH), the serum concentrations of the hypohyseal thyroxine stimulating hormone (TSH) and prolactin (PRL) were measured by radioimmunoassay (RIA). In 7 of the patients (23%), we found increased TSH levels after stimulation with TRH--indicative of hypothyroidism. In 9 of the patients (29%), we observed increased PRL levels after TRH stimulation, indicating prolactinemia. TSH and PRL can interact with androgen metabolism at various levels. Thyroxine may influence the unbound, metabolically active testosterone via the sex hormone binding globulin (SHBG). Prolactine, which is stimulated by TRH, promotes the suprarenal cortisol and androgen production. In 48% of the patients, we found either hypothyroidism or hyperprolactinemia. This suggests that both conditions may contribute to the clinical picture of female androgenetic alopecia, as they interfere with the androgen metabolism.     

A theory of family,economy, and gender

Historically, the requirements of population replacement have interacted with modes of subsistence technology to shape the differential distribution of power and prestige by sex. Two assumptions undergird Huber's argument: in all societies, producers have more power than consumers; those who control the distribution of valued goods beyond the family have the most power. Evidence comes from societies based on foraging, the hoe, the plow, herding, and industrial technologies. Huber concludes that changes in the work people do have altered the stratification and family systems of plow societies. Declines in mortality and fertility and changes in lactation customs have reduced the time that women spend pregnant or nursing. Increases in educational levels and employment rates enable women to provide sizable shares of family income. These trends have increased the centrality of individual goal attainment in the Western ideational system. Now women, along with men, have been swept into the occupational streams of the industrial revolution, though not quite into the mainstream. Still in question is the extent to which women will hold a fair share of top positions. This will hinge on responsibility for housework and childcare early in a woman's career, a time when most single parents or couples lack resources to command full-time quality care for the daily needs of their children. Ambitious women can avoid much conflict by remaining childless, but that is the point; ambitious men need not make that choice. Women cannot become men's social equals until the most talented women can aspire as realistically as their male counterparts to contribute in proportion to their talents. Thus, the overlap of family, economy, and gender, reshaped by continuing technological change, continues to affect women's status. Industrialization 1st turned the cost-benefit ratio of children upside down. Then wives were drawn into the labor force, raising the opportunity cost of their time, and thereby the cost of children. Now, below-replacement fertility in the West has highlighted the problem of population maintenance. Parenthood may have to be made more attractive by limiting the hours of responsibility. Such measures would be expensive but they would raise women's status in the family and in society in ways that were unimaginable a few decades ago.     

Studies of the mechanism of tolerance induced by short-term immunosuppression with cyclosporine in high-risk corneal allograft recipients. I. Analysis of CTL precursor frequencies

Transplantation of unmatched allogeneic corneas into highly vascularized recipient eyes under the cover of short-term immunosuppression with cyclosporine enables permanent engraftment. The aim of this study was to further elucidate the mechanism(s) underlying this tolerant state. In eight "high-risk" cornea recipients the clone sizes of donor-specific and third-party reactive cytotoxic T cell precursors were assessed by limiting dilution analyses before and at three and six months after transplantation. Acquired allograft tolerance in these patients was not accompanied by clonal reduction of donor-specific CTL-p, whereas in the case of an irreversible rejection the donor-specific CTL pool size was significantly enlarged. This donor-specific CTL-p increase could already be seen two months before clinical manifestation. These patterns differed from that of tolerant renal transplant patients, in whom marked and donor-specific reduction of CTL-p was observed. During rejection identical patterns with increasing donor-specific CTL-p frequencies were seen in both groups of patients. We conclude that induction of tolerance by short-term CsA to unmatched cornea grafts is not caused by clonal reduction of the effector precursor cell pool.     

Altered responsiveness to stress and NMDA following prenatal exposure to cocaine

Pregnant Sprague--Dawley rats were treated once daily with 40-mg/kg cocaine or saline from gestation days (GD) 12 to 21. A third group of pregnant dams was used as a pairfed control. Male and female offspring were examined for stress endurance response as determined by the cold-water swim test on postnatal days (PND) 21, 30, 40, and 60. Male and female offspring exposed to cocaine in utero were found to have diminished tolerance and altered hormonal response to stress. Moreover, prenatal cocaine exposure has been associated with significant increases in severity of N-methyl-D-aspartate (NMDA; 35 mg/kg) behavioral responses (tail twitches, wetdog shaking, and convulsion) as compared to control. Examining the experimental groups for pain sensitivity using the tail-flick and the hot-plate methods indicated that prenatal cocaine exposure altered pain sensitivity. NMDA receptor binding studies showed an increase in receptor density in the hippocampus and hypothalamus of the cocaine-treated group. These results indicate that gestational cocaine exposure is associated with long-term alterations in response to stress, NMDA receptor, and pain sensitivity in the rat offspring.     

Electrophysiologic studies on the pallido- and cerebellothalamic projections in squirrel monkeys (Saimiri sciureus)

Summary Thalamic projections of the pallidum and the deep cerebellar nuclei were studied by unitary recordings as well as field potential analysis in the thalamus of squirrel monkeys (Saimiri sciureus) under sodium pentobarbital anesthesia.Stimulation of the pallidum produced a positive field potential preceded by incoming afferent fiber volleys in the thalamus. Spontaneous discharges of thalamic neurons were suppressed during this positive potential, and intracellular recordings from the thalamic neurons revealed that the time course of this field potential corresponded to that of the hyperpolarizing potential. The hyperpolarization was presumed to be a monosynaptic inhibitory postsynaptic potential by the short synaptic delay (about 0.5–0.7 ms) and responsiveness to high frequency stimulation (over 150 Hz). The positive field potential on stimulation of the external pallidal segment was distributed in L.po (VA) and the reticular thalamic nucleus around L.po, whereas that on stimulation of the internal segment was in V.o.a (the anterior basal part of VL) and in Z.o (upper part of VL). The projection of the external segment appeared to be less dense than that of the internal segment.The projection of deep cerebellar nuclei was situated in V.o.a, V.o.p (posterior part of basal part of VL), V.o.i (VLm), the intralaminar nucleus (CL), and some part of V. im (the rostral part of VPLo). Projections of the interpositus and dentate nuclei were distributed in a more anterior part than those of the fastigial nucleus. A certain topographical arrangement of the projections of these three nuclei was found in V.o.p, V.o.i and V.im. No significant overlap was detected between projections of the pallidum and the deep cerebellar nuclei within the thalamus.