Ischemic mitral valve regurgitation: the new challenge for magnetic resonance imaging.

Ischemic mitral valve regurgitation (IMVR) refers to mitral regurgitation in patients with ischemic heart disease (IHD) in the presence of a structurally normal mitral valve. IMVR contributes significantly to morbidity and mortality in patients with IHD. The thresholds for clinical management, surgical intervention, and the choice of surgical procedure continue to evolve and independent determinants for surgical success in the pre- and post-operative evaluation of IMVR are still controversial. Although echocardiography has been valued as the gold standard in the evaluation of IMVR, new technologies such as magnetic resonance imaging (MRI) may be seen as applicable to the investigation of this complex pathology. MRI may allow for detection of parameters that could help clinicians and surgeons to better assess IMVR and eventually guide appropriate treatment whenever necessary. The present article discusses the main parameters that should be routinely investigated while adopting MRI technology to assess patients with IMVR. The review is the result of a multidisciplinary approach to this complex etiopathogenic entity and involves expertise spanning from radiology, cardiology, to cardiac surgery.     

Characterization of granulosa cell subpopulations from avian preovulatory follicles by multiparameter flow cytometry

The objective of the present study was to characterize the granulosa cell populations from individual hen (Gallus domesticus) preovulatory follicles at defined stages of follicular maturation using multiparameter flow cytometry. Granulosa cells were fixed and stained with three fluorochromes that selectively bind to DNA (Hoechst 33342, blue), RNA (pyronin Y, red), or protein (fluorescein isothiocyanate, green). A flow cytometer equipped with a three-laser excitation system was used to analyze three colors of fluorescence from stained cells. Forward angle light scatter and axial light loss measurements were made on each cell to determine relative cell size. In addition, the ratios of RNA to protein and DNA to protein were measured. The major findings obtained from correlated measurements of cell cycle (DNA), protein, RNA, cell size, and ratios were: 1) the percentage of proliferating cells decreased while cell size increased during follicular maturation; 2) two subpopulations of granulosa cells were identified within each follicle based on relatively high and low protein contents; the fraction of cells in the high protein subpopulation increased, and the fraction of cells in the low protein subpopulation decreased during follicular maturation; 3) the high and low protein subpopulations also differed in cell cycle distribution, RNA content, and cell size; and 4) the distribution of cells into the two subpopulations and the degree of proliferation were influenced by stage of the ovulatory cycle, primarily in the most mature follicles. The results demonstrate the dynamic heterogeneity of the granulosa cell populations from individual ovarian follicles and show the influences of follicular maturation and stage of the ovulatory cycle on cell growth and metabolism.     

Respiration in NREM and REM sleep after upper airway surgery for obstructive sleep apnoea

SUMMARY  To verify whether upper airway surgery in obstructive sleep apnoea syndrome affects differently respiration in NREM and REM sleep, 22 patients were studied by polysomnography before and three months after surgical treatment. On the average, treatment improved respiration during both sleep states, but no significant interaction was found between sleep state and effect of surgical treatment. According to the response to treatment, three groups of patients were identified: the first group ( N = 6), with an improvement in apnoea-hypopnoea index (AHI), percentage of sleep time spent in apnoea and hypopnoea (time in AH) and mean oxyhaemoglobin saturation (SaO₂) in both NREM and REM sleep; the second group ( N = 5), with an improvement in AHI only in NREM sleep, associated with improvement in mean SaO₂ in both sleep states; the third group ( N = 11), without any improvement in AHI and time in AH, either associated ( N = 5) or not ( N = 6) with an improvement in mean SaO₂ in both sleep states. An increase in the percentage of hypopnoeas out of the total AHI after treatment could partly account for the apparent discrepancy between AHI and mean SaO₂ behaviour in the subjects of the second group, but not in the patients of the third group who improved their mean SaO₂. Mixed apnoeas occurred before surgery in six subjects; they remained numerous after surgery only in two subjects who did not show any SaO₂ improvement. In conclusion, the degree of improvement in respiration after upper airway surgery was similar in every patient in NREM and REM sleep.     

Nylon-fiber-induced neutrophil fragmentation

We have investigated the effects of mechanical elution of neutrophils from nylon-wool fiber (NWF) using the scanning electron microscope and biochemical analysis of elution fractions. We have determined that mechanical removal of neutrophils from nylon-wool fiber disrupts neutrophils adherent to nylon-wool fiber and augments release of granules, release of peripheral cytoplasmic fragments, and release of lactic dehydrogenase, a soluble cytoplasmic enzyme. Mechanical shearing of the adherent cell, and not adherence per se, causes the fragmentation. The extent of fragmentation is proportional to the NWF surface area available to neutrophils and is maximal at the temperature for optimal adherence and spreading. Agents that decrease cell spreading (n-ethylmaleimide and cold) diminish fragmentation. Cytochalasin B, an agent that destabilizes the neutrophil cortex, increases fragmentation. Fragmentation may be an important contributing cause of the abnormal morphology, function, and in vivo survival of nylon-wool-fiber procured human neutrophils. The prevention of fragmentation would appear to be necessary to insure the procurement of optimally functioning cells. Elution of NWF-adherent neutrophils in the cold might be a practical way to diminish neutrophil damage during clinical filtration leukapheresis.     

Expiratory timing in obstructive sleep apnoeas

Diaphragmatic electromyogram was recorded during NREM sleep in 4 patients affected by obstructive sleep apnoea (OSA) syndrome in order to evaluate the behaviour of expiratory time (TE) in the course of the obstructive apnoea-ventilation cycle. The two components of TE, i.e. time of post-inspiratory inspiratory activity (TPIIA) and time of expiratory phase 2 (TE2) were separately analysed. TPIIA showed a short duration, with only minor variations, within the apnoea, while its duration was more variable and longer in the interapnoeic periods: the longest TPIIA values were associated with the highest inspiratory volumes in the same breaths. This behaviour seemed regulated according to the need of a more or less effective expiratory flow braking, probably as a result of pulmonary stretch receptors discharge. Conversely TE2 showed a continuous gradual modulation, progressively increasing in the pre-apnoeic period, decreasing during the apnoea and increasing in the post-apnoeic period: these TE2 variations seemed related to oscillations in chemical drive. These data show that TE in the obstructive apnoea-ventilation cycle results from a different modulation in its two components and suggest that both mechanical and chemical influences play a role in its overall duration.