3D printed microchannels for sub-nL NMR spectroscopy.

Nuclear magnetic resonance (NMR) experiments on subnanoliter (sub-nL) volumes are hindered by the limited sensitivity of the detector and the difficulties in positioning and holding such small samples in proximity of the detector. In this work, we report on NMR experiments on liquid and biological entities immersed in liquids having volumes down to 100 pL. These measurements are enabled by the fabrication of high spatial resolution 3D printed microfluidic structures, specifically conceived to guide and confine sub-nL samples in the sub-nL most sensitive volume of a single-chip integrated NMR probe. The microfluidic structures are fabricated using a two-photon polymerization 3D printing technique having a resolution better than 1 µm3. The high spatial resolution 3D printing approach adopted here allows to rapidly fabricate complex microfluidic structures tailored to position, hold, and feed biological samples, with a design that maximizes the NMR signals amplitude and minimizes the static magnetic field inhomogeneities. The layer separating the sample from the microcoil, crucial to exploit the volume of maximum sensitivity of the detector, has a thickness of 10 µm. To demonstrate the potential of this approach, we report NMR experiments on sub-nL intact biological entities in liquid media, specifically ova of the tardigrade Richtersius coronifer and sections of Caenorhabditis elegans nematodes. We show a sensitivity of 2.5x1013 spins/Hz1/2 on 1H nuclei at 7 T, sufficient to detect 6 pmol of 1H nuclei of endogenous compounds in active volumes down to 100 pL and in a measurement time of 3 hours. Spectral resolutions of 0.01 ppm in liquid samples and of 0.1 ppm in the investigated biological entities are also demonstrated. The obtained results may indicate a route for NMR studies at the single unit level of important biological entities having sub-nL volumes, such as living microscopic organisms and eggs of several mammalians, humans included.

Anatomy of stroke, Part II: volumetric characteristics with implications for the local architecture of the cerebral perfusion system.

BACKGROUND AND PURPOSE: The margin of a stroke is assumed to approximate a trace of the isobar of the perfusion threshold for infarction at the time that infarction occurred. Working from this hypothesis, we have analyzed stroke topography and volume in MR images obtained at a time remote from the stroke event. We have derived parameters from these images that may give information on local perfusion competence and microvascular architecture because they influenced the contour of stroke at the time infarction occurred. METHODS: MR images were obtained months after presumed embolic middle cerebral artery stroke in 21 subjects. Volumetric analyses of image data were undertaken with respect to the tissue shape of stroke and scaling ratios of anatomic partitions involved in stroke. RESULTS: For stroke confined to a single volume, the 3-dimensional form conforms to a parabola in which the height-to-width ratios are variable. The ratio for cortex is greater than that for underlying white matter. Scaling ratios indicate a close correlation between volume of cortex and radiata destroyed and total volume of stroke, but the relative proportions vary as a function of location within the M4 territory. CONCLUSIONS: Scaling ratios for cortex and radiata to stroke volume are consistent with vascular studies that depict a modular microvascular perfusion architecture for the cortex and underlying white matter. The stroke descriptors are inferred to be related to the competence of collateral perfusion at the time that stroke occurred. This inference may be tested by serial volumetric analysis of the perfusion-diffusion examination mismatch immediately and over the longer-term evolution of stroke.

Anatomy of stroke, Part I: an MRI-based topographic and volumetric System of analysis.

BACKGROUND AND PURPOSE: The clinical diagnosis and treatment of stroke, as well as investigations into the underlying pathophysiology of the disease, hinge on inferences from the anatomy of the stroke lesion. We describe an MRI-based system of topographic and volumetric analysis that considers distribution of infarct with respect to neuroanatomic structures, superficial and deep perfusion compartments, and gray and white matter tissue types. METHODS: MRI-based 3-dimensional topographic and volumetric analysis of presumed MCA embolic stroke was performed months after the acute event in 21 subjects ranging in age from 34 to 75 years. RESULTS: The topography of infarction was greatly variable, with virtually all regions of the MCA territory involved in at least 1 stroke in the series. In 14, there was involvement of the M1 as well as the M2 through M4 territories; in 6, there was involvement of only the M2 through M4 territories; and in 2, there was involvement of only the M1 territory. The volumes varied from 3.1 to 256 cm3, corresponding approximately to a range of 1% to 90% of the total MCA territory. CONCLUSIONS: The system of topographic and volumetric analysis is generally applicable to all strokes in the forebrain where the infarct is visualized in MRI, independent of vascular territory, clinical correlates, and interval between stroke and MRI. The results emphasize the variety of topographic patterns and lesion volumes of strokes. Intended long-range applications include correlation of outcome of stroke with predictions from acute-phase diffusion- and perfusion-weighted imaging and investigations of the potential benefit of therapeutic agents.

Hemorrhagic transformation of brain infarct: predictability in the first 5 hours from stroke onset and influence on clinical outcome.

OBJECTIVE: To identify, in the first 5 hours of acute brain infarct, clinical and radiologic predictors of subsequent hemorrhagic transformation (HT), and to evaluate its influence on the clinical course. BACKGROUND: The identification of early predictors of HT might be important to plan antithrombotic or thrombolytic treatments. PATIENTS: One hundred fifty consecutive patients with cerebral anterior circulation infarct systematically underwent a first CT within 5 hours of onset. During the first week after stroke, we performed a repeat CT or autopsy to look for HT. Outcome measures were early neurologic deterioration within the first week of onset and 30-day case fatality rate and disability. RESULTS: HT was observed in 65 patients (43%): 58 (89%) had a petechial HT and seven (11%) a hematoma. Among initial clinical an CT findings, the only independent predictor of HT was early focal hypodensity. Its presence was associated with subsequent HT in 77% of cases (95% CI, 68 to 86%), whereas its absence predicted the absence of subsequent HT in 94% of cases (95% CI, 89 to 99%). No baseline clinical or CT characteristic differentiated patients with petechial HT from those with hematoma. Antithrombotic and antiplatelet agents did not influence the occurrence of either type of HT. The frequency of early neurologic deterioration and of 30-day death or disability in HT patients was twice as high as in those without HT. However, a large-sized infarct and the presence of mass effect at the repeat CT or autopsy were the only factors independently linked to both the outcome events, irrespective of the development of HT. Clinical evolution of HT patients given antithrombotics was comparable with that of HT patients not receiving these drugs. CONCLUSIONS: HT of a brain infarct is a common event that occurs independently of anticoagulation and can be reliably predicted as early as 5 hours from stroke onset by the presence of focal hypodensity at CT. Apart from the infrequent cases of massive hematoma, HT does not influence prognosis, whereas a poor outcome in HT patients is correlated with a higher frequency of large edematous infarcts in this subgroup. The clinical course and final outcome of HT in anticoagulated patients does not differ from that of non-anticoagulated HT patients.

Fungal infections in patients undergoing bone marrow transplantation: an approach to a rational management protocol.

Candida sp. and Aspergillus sp. are the most common fungal pathogens causing infection in bone marrow transplant recipients and represent an increasing cause of morbidity and mortality. At this time there is no generally accepted rule for the antifungal management of these complications. Antifungal drugs in immunocompromised patients are usually administered for prophylaxis, for therapy of specific infections or for empirical or preemptive therapy. The present article reports schedules of administrations and pediatric and adult dosages of the main antifungal drugs presently available, (fluconazole, itraconazole, amphotericin B deoxycholate, lipid formulations of amphotericin B and flucytosine), together with their spectrum of action and main toxicities. Thereafter, the available information about prevention and treatment of fungal infections in bone marrow transplant recipients is summarized. Briefly, fluconazole remains the drug of choice for prevention of Candida infections in bone marrow transplant recipients, while itraconazole has been seldomly used for this indication, due to erratic oral absorption. However, new itraconazole formulations are being studied, that might disclose new clinical perspectives, due to improved bioavailability. The duration of prophylaxis is still an open issue. Resistance to the new azoles may become a problem in the near future. For this reason, it is likely that the approach to the use of these new drugs should be similar to the one commonly used for antibacterial drugs, i.e. based on pathogen-related, drug-related and host-related factors. Mainly due to lack of diagnostic tools, very little studies have been performed for prevention of aspergillosis. Available data seem to show that there might be a role for low-dose intravenous amphotericin B, which has shown to be effective for secondary prophylaxis. Itraconazole and intranasal amphotericin B have been studied, as well. Although fluconazole and itraconazole (in the rare instances in which the oral route is reliable) can also have therapeutic indications, both for empirical and for specific therapy, amphotericin B (with or without flucytosine) remains the main therapeutic option. New antifungal drugs and new supportive strategies (i.e. role of hematopoietic growth factors) are in the research pipeline and will hopefully disclose new perspectives in the near future.

Thrombolysis acute ischemic stroke.

Thrombolysis is an attractive but potentially dangerous they for cerebral ischemia: it is capable of dissolving an arterial thrombus, but can also transform a pale infarct into a hematoma and/or may cause severe oedema and herniation. The safety and efficacy of the treatment critically depend on the timing of intervention ad on patient selection. In recent studies on ischemic stroke, spontaneous hemorrhagic transformation of an infarct seems to be related to the size of the lesion, and can be reliably predicted as early as five hours from stroke onset by the presence of focal hypodensity in the CT scan. That is why in the European Co-operative Acute Stroke (ECASS), a randomised, double blind trial on intravenous rt-PA in hemispheric stroke, patients showing, on the admission CT scan, extended early hypodensity, involving more than one third of the territory of the middle cerebral artery, were excluded from the day. Other ongoing trials on thrombolytic agents are expected to provide further indications on how to identify those patients most likely to benefit and least likely to experience adverse effects from this treatment.

[Sepsis related to a permanent central venous catheter in children with neoplastic disease: practical implications of a continuous surveillance of the etiology]. / Sepsi correlate a catetere venoso centrale a permanenza in bambini affetti da malattia neoplastica: implicazioni pratiche di una sorveglianza continua dell'eziologia.

Indwelling central venous catheter-related bacteremias are an important complication in patients with cancer. In general they are due to Staphylococcus aureus and Candida, while bacteremias caused by Gram-negatives are less common and often related to infusate contaminans. We describe a survey of etiological surveillance of Broviac catheter-related infections at G. Gaslini Children's Hospital of Genoa, Italy. In the period 1989-1992 an increase of Broviac catheter-related bacteremias due to Gram-negatives was demonstrated as compared with previous years (1985-1988). At home parental management was suspected as an important risk factor, since this complication was frequently due to infusate contaminants and no epidemic cluster or positive surveillance culture was observed in the Hospital. Therefore at home management was changed, especially regarding heparin storage. The subsequent, prospective follow-up from July 1993 to December 1995 showed a significant decrease in catheter-related bacteremias due to Gram-negatives (P = 0.003, chi-square test). In conclusion, a strict control on at home catheter management procedures must be maintained in order to reduce the risk of indwelling central venous catheter-related infections in children with cancer.

Multiple myeloma and paget disease with abnormal skull lesions and intracranial hypertension.

We report a 73 years old man with a diagnosis of Paget Disease (PD) and symptomatic Multiple Myeloma (MM). Coexistence of MM and PD has rarely been described. PD mimics many of the features of bone destructive process in MM, making differential diagnosis more complicated. In addition, the presence of serious muscolo-skeletal and metabolic complications in both diseases makes management of patients difficult, worsening the prognosis.The comparison of these two diseases has led to the characterization of a common molecular mechanism represented by the receptor activator of nuclear factor-kB ligand (RANKL)/Osteoprotegerin signaling pathway. The improved comprehension of these mechanisms led to the development of new pharmacologic agents (bisphosphonates, cytokines inhibitors) effective for the treatment of these bone diseases.

Clinical and prognostic correlates of stroke subtype misdiagnosis within 12 hours from onset.

BACKGROUND AND PURPOSE: Pure motor hemiparesis and sensorimotor stroke syndromes are not accurate predictors of lacunar infarct when described in the first 12 hours of stroke onset. We evaluate here whether this inaccuracy of clinical diagnosis might have influenced the planning of patient management either in routine practice or in therapeutic trials. METHODS: A consecutive hospital series of 517 first-ever ischemic hemispheric stroke patients presented lacunar or nonlacunar syndromes at the first examination within 12 hours of the event. A distinction was subsequently made, by means of a CT scan or autopsy performed within 15 +/- 2 days of stroke, between patients affected by lacunar or nonlacunar infarcts. We compared stroke risk factors, considered to be indicative of potential pathogenetic mechanisms, and the clinical outcome of lacunar infarct versus nonlacunar infarct patients and those of lacunar syndrome versus nonlacunar syndrome patients. RESULTS: Two hundred nineteen patients (42%) presented a lacunar syndrome and 298 (58%) a nonlacunar syndrome, while 170 (33%) had lacunar infarcts and 347 (67%) nonlacunar infarcts. Lacunar infarct patients were more frequently associated with hypertension and a previous transient ischemic attack and less frequently with atrial fibrillation when compared with their nonlacunar infarct counterparts, whereas no differences were apparent between lacunar syndrome and nonlacunar syndrome patients. Logistic regression analysis showed that hypertension and a previous transient ischemic attack on the one hand and atrial fibrillation on the other were strongly correlated with the diagnosis of lacunar infarct and nonlacunar infarct, respectively, while no risk factor was correlated with the diagnosis of lacunar syndrome. Twenty-two percent of lacunar infarct patients and 68% of nonlacunar infarct subjects had a poor outcome (death plus disability of survivors) as opposed to 40% of lacunar syndrome and 63% of nonlacunar syndrome patients. Logistic regression selected age, severity of neurological deficit at entry, cardiopathies, diabetes, and lacunar infarct, but not lacunar syndrome, as predictors of outcome. CONCLUSIONS: The inaccurate clinical diagnosis of lacunar infarct made in the first 12 hours of stroke might lead to no distinction being made between stroke subgroups with potentially different pathogenetic mechanisms and prognostic estimates, thus negatively influencing the planning of patient management.