Citations

Although tight regulation of intracellular pH (pHi) is critical for the survival under stress, paradoxically a slowed recovery of pHi under hypoxic injury may be cardioprotective. In this study, we investigated the recovery of pHi after hypoxia-induced intracellular acidosis in cardiomyocytes loaded with the H+-sensitive dye SNARF-1. Exposure of single cardiomyocytes to 2,4-dinitrophenol (DNP), an inhibitor of mitochondrial oxidative phosphorylation, induced significant intracellular acidification. However, within 10–12 min upon removal of DNP, cardiomyocytes restituted their intracellular H+ concentration. The presence either of 5-N-ethyl-N-isopropylamiloride (EIPA) an inhibitor of Na/H antiporter, or 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS), an inhibitor of bicarbonate-dependent exchange, did not modify the cellular response to DNP. But, combined use of EIPA and DIDS prevented the restitution of intracellular pH following removal of DNP. This study, thus, demonstrated, for the first time, that blockade of both Na/H and bicarbonate-dependent exchange is necessary and sufficient to maintain the hypoxia-induced intracellular acidification. Therefore, concomitant blockade of both pH-regulating mechanisms deserves to be further considered as a novel strategy against hypoxia-reoxygenation injury in the heart.

An Italian version of the Disability of the Arm, Shoulder and Hand (DASH) questionnaire has been devised and its reliability and validity have been assessed in a cross-sectional study of 108 consecutive patients with upper extremity pathologies. A sub-sample of 30 patients was used to assess re-test reliability. The principal DASH scale showed a high correlation with other patient-oriented measures and demonstrated good reproducibility, consistency and validity, which were similar to those for other languages’ versions of DASH. These findings suggest that the evaluation capacities of the Italian DASH are equivalent to those of other language versions of the DASH.

The mechanisms by which mammalian cells remodel the actin cytoskeleton in response to motogenic stimuli are complex and a topic of intense study. Dynamin 2 (Dyn2) is a large GTPase that interacts directly with several actin binding proteins, including cortactin. In this study, we demonstrate that Dyn2 and cortactin function to mediate dynamic remodeling of the actin cytoskeleton in response to stimulation with the motogenic growth factor platelet-derived growth factor. On stimulation, Dyn2 and cortactin coassemble into large, circular structures on the dorsal cell surface. These “waves” promote an active reorganization of actin filaments in the anterior cytoplasm and function to disassemble actin stress fibers. Importantly, inhibition of Dyn2 and cortactin function potently blocked the formation of waves and subsequent actin reorganization. These findings demonstrate that cortactin and Dyn2 function together in a supramolecular complex that assembles in response to growth factor stimulation and mediates the remodeling of actin to facilitate lamellipodial protrusion at the leading edge of migrating cells.

The degradation of extracellular matrix (ECM) by matrix metalloproteases is crucial in physiological and pathological cell invasion alike. Degradation occurs at specific sites where invasive cells make contact with the ECM via specialized plasma membrane protrusions termed invadopodia. Herein, we show that the dynamin 2 (Dyn2), a GTPase implicated in the control of actin-driven cytoskeletal remodeling events and membrane transport, is necessary for focalized matrix degradation at invadopodia. Dynamin was inhibited by using two approaches: 1) expression of dominant negative GTPase-impaired or proline-rich domain-deleted Dyn2 mutants; and 2) inhibition of the dynamin regulator calcineurin by cyclosporin A. In both cases, the number and extension of ECM degradation foci were drastically reduced. To understand the site and mechanism of dynamin action, the cellular structures devoted to ECM degradation were analyzed by correlative confocal light-electron microscopy. Invadopodia were found to be organized into a previously undescribed ECM-degradation structure consisting of a large invagination of the ventral plasma membrane surface in close spatial relationship with the Golgi complex. Dyn2 seemed to be concentrated at invadopodia.

Objective. To highlight the clinical profiles and angiographic findings of two patients with recurrent thunderclap headache (TCH) without subarachnoid hemorrhage (SAH) and to present modified diagnostic criteria for this unusual syndrome. Background. TCH may be a benign recurrent headache disorder or it may represent a serious underlying process such as SAH or venous sinus thrombosis. The pathophysiology of this disorder in the absence of underlying pathology is not well understood and its potential angiographic features are not well appreciated. Methods. Two case descriptions with illustrative angiography. Results. Both cases demonstrated the potential for reversible intracranial vasospasm without intracranial aneurysm or SAH and a benign clinical outcome. Conclusions. Primary TCH has a distinctive clinical and angiographic profile and must be distinguished from central nervous system vasculitis and SAH.

Hypnic headache syndrome is a rare, sleep-related, benign headache disorder. We report 19 new cases (84% females) with follow-up data. The mean age at headache onset was 60.5 ± 9 years (range 40–73 years). Headache awakened the patients from the night's sleep at a consistent time, usually between 1.00 and 3.00 a.m. (63%); three patients (16%) reported that identical headaches could occur also during daytime naps. Headache frequency was high, occurring more than 4 nights/week in 68% of the patients. Headache resolution occurred within 2 h in 68% of patients. Neurologic examination, laboratory studies, and brain imaging were unrevealing at the time of diagnosis. Headache severity largely remains unchanged or attenuates over time, but frequency may vary in either direction. Only one patient had spontaneous relief from headache. Four patients (24%) achieved permanent suppression of headache with medication, and two were able to abort individual headache attacks. Caffeine in a tablet or beverage was helpful in four patients. Lithium carbonate therapy caused side effects requiring cessation of treatment in four patients.