Solid-state electron spin lifetime limited by phononic vacuum modes.

Longitudinal relaxation is the process by which an excited spin ensemble decays into its thermal equilibrium with the environment. In solid-state spin systems, relaxation into the phonon bath usually dominates over the coupling to the electromagnetic vacuum1-9. In the quantum limit, the spin lifetime is determined by phononic vacuum fluctuations 10 . However, this limit was not observed in previous studies due to thermal phonon contributions11-13 or phonon-bottleneck processes10, 14,15. Here we use a dispersive detection scheme16,17 based on cavity quantum electrodynamics18-21 to observe this quantum limit of spin relaxation of the negatively charged nitrogen vacancy (NV-) centre 22 in diamond. Diamond possesses high thermal conductivity even at low temperatures 23 , which eliminates phonon-bottleneck processes. We observe exceptionally long longitudinal relaxation times T1 of up to 8 h. To understand the fundamental mechanism of spin-phonon coupling in this system we develop a theoretical model and calculate the relaxation time ab initio. The calculations confirm that the low phononic density of states at the NV- transition frequency enables the spin polarization to survive over macroscopic timescales.

γδT Cells Are Essential for Orthodontic Tooth Movement.

Sustained mechanical forces applied to tissue are known to shape local immunity. In the oral mucosa, mechanical stress, either naturally induced by masticatory forces or externally via mechanical loading during orthodontic tooth movement (OTM), is translated, in part, by T cells to alveolar bone resorption. Nevertheless, despite being considered critical for OTM, depletion of CD4+ and CD8+ T cells is reported to have no impact on tooth movement, thus questioning the function of αßT cells in OTM-associated bone resorption. To further address the role of T cells in OTM, we first characterized the leukocytes residing in the periodontal ligament (PDL), the tissue of interest during OTM, and compared it to the neighboring gingiva. Unlike the gingiva, monocytes and neutrophils represent the major leukocytes of the PDL. These myeloid cells were also the main leukocytes in the PDL of germ-free mice, although at lower levels than SPF mice. T lymphocytes were more enriched in the gingiva than the PDL, yet in both tissues, the relative fraction of the γδT cells was higher than the αß T cells. We thus sought to examine the role of γδT cells in OTM. γδT cells residing in the PDL were mainly Vγ6+ and produced interleukin (IL)-17A but not interferon-γ. Using Tcrd-GDL mice allowing conditional ablation of γδT cells in vivo, we demonstrate that OTM was greatly diminished in the absence of γδT cells. Further analysis revealed that ablation of γδT cells decreased early IL-17A expression, monocyte and neutrophil recruitment, and the expression of the osteoclastogenic molecule receptor activator of nuclear factor-κß ligand. This, eventually, resulted in reduced numbers of osteoclasts in the pressure site during OTM. Collectively, our data suggest that γδT cells are essential in OTM for translating orthodontic mechanical forces to bone resorption, required for relocating the tooth in the alveolar bone.

Manual Ability Measure (MAM-16): a preliminary report on a new patient-centred and task-oriented outcome measure of hand function.

The purpose of this study was to develop an easy-to-use and psychometrically sound outcome instrument that is task-oriented and patient-centred. One hundred fifteen patients with a variety of hand impairments completed a rating scale of perceived manual ability (i.e., the Manual Ability Measure). The first 70 patients also completed two other questionnaires about physical health and psychological well-being. Rasch Analyses were conducted to transform the ordinal ratings into linear measures; Rasch statistics were used to evaluate its measurement properties at both scale and item levels. Eighty-three original items were reduced to 16 common tasks; Rasch reliabilities were good; the easy-to-difficult item hierarchy makes sense clinically. Moderate correlations were found between manual ability, physical function and general sense of well-being. The results of this preliminary study suggest that the MAM is a promising outcome measure that has adequate psychometric properties and can be used to complement other objective clinical measurements.

A new lithium alkoxide accelerated diastereoselective cyanation of ketones.

[reaction: see text] A remarkably general lithium heteroatom assisted TMSCN or TBSCN addition to aldehydes and ketones has been discovered. The process provides excellent selectivities and high rates. Conformationally constrained ketones such as camphor, fenchone, and nopinone give excellent diastereoselectivities with TMSCN. Reduction of 2 provided diastereopure amino alcohol 3 in good yield. alpha- and beta-Methyl cyclohexanones with TBSCN-LiOR afford high diastereoselectivities and yields.

Shunt-associated glomerulonephritis.

Six patients with glomerulonephritis in association with a ventriculovascular shunt were treated with three basic modes of therapy. Direct intraventricular instillation of antibiotic was used on seven occasions in five patients either as the definitive mode of therapy or as an adjunct to shunt removal. Ventricular fluid antibiotic concentrations were monitored in two patients and demonstrate that effective levels as compared to the specific minimal inhibitory concentration can only be achieved by this method. With resolution of the shunt infection, improvement in the clinical and laboratory parameters of renal function was noted. A recommended treatment protocol is outlined, including specific dosages for intraventricular antibiotics. The need for detailed and frequent post-treatment examination including serum immunoglobulin profile is stressed.

Relationships among cortical ischemia, infarction, and hemorrhage in eclampsia.

Cerebral infarction and hemorrhage are well-known cerebrovascular complications of eclampsia. A 30-year-old woman with eclampsia developed bilateral posterior parietal and occipital hemorrhages 4 hours after computed tomography demonstrated lucencies indicative of ischemia or infarction within the same regions. The association between infarction and hemorrhage has not been previously documented by computed tomography in eclampsia. Review of the pathophysiological mechanisms and associated risk factors has prompted a more aggressive prophylactic therapeutic approach.

Intradural spinal metastasis in Ewing's sarcoma: case report and review of the literature.

Ewing's sarcoma is a rare primary osseous neoplasm of children and young adults. The use of radiotherapy and adjuvant chemotherapy has favorably influenced the outcome of patients and dramatically reduced the rate of local disease recurrence. However, distant metastasis, usually to the lung and skeletal system, continues to be a frequent preterminal event. Metastasis to the central nervous system is infrequent unless related to adjacent bone involvement. We report a case of intraneural, intradural metastasis in a young man with a previously treated Ewing's sarcoma of the ilium. Metastasis to this part of the nervous system has not been previously reported.

Compressive myelopathy associated with type VI mucopolysaccharidosis (Maroteaux-Lamy syndrome).

Spinal cord compression with resultant myelopathy is a frequent occurrence in patients with mucopolysaccharidoses. Etiological factors include developmental abnormalities of the cervical spine and infiltration of the dura mater by the accumulated products of mucopolyssacharide metabolism. Compression at the thoracolumbar junction is rare, but was found in a child with the characteristic physical and biochemical stigmata of the Maroteaux-Lamy syndrome (mucopolysaccharidosis VI). An anterolateral approach to remove the compressing bony elements resulted in symptomatic improvement. Careful radiological evaluation is required so that all surgical options can be considered. Patients with metabolic storage diseases and the capacity for normal intellectual function warrant aggressive surgical care to optimize neurological function.

Prophylactic vena cava filter insertion in patients with traumatic spinal cord injury: preliminary results.

Pulmonary embolism (PE) is a devastating complication in patients with traumatic spinal cord injury (SCI). Prophylactic measures such as venous compression hose or low-dose heparin are only partially protective in reducing the risk of venous thromboembolism and are contraindicated in some patients. Because of extended perturbations in fibrinolytic activity, catecholamine effects on platelet aggregation, increased activity of complement and acute phase reactants, abnormally high factor VIII concentrations, and persistent venous stasis with ongoing endothelial damage, the patient with an SCI remains at prolonged risk for venous thromboembolism. A retrospective 5-year review at the Medical Center Hospital of Vermont revealed seven patients with eight documented PEs (three fatal; 2.7%) in 111 SCI patients (6.3%). Six PEs (75%) occurred after discharge from the acute care facility. Median time to PE after injury was 78 days (range, 9-5993). Although comprising only 4% of all trauma admissions, SCI accounted for 31% of all PEs in the total trauma population (2525 patients). Beginning in July 1991, a new prophylaxis protocol was instituted, which included the percutaneous insertion of vena cava filters under local anesthesia in all SCI patients with paraplegia or quadriplegia. Fifteen patients have undergone the insertion of titanium filters. Impedance plethysmography was performed weekly to detect deep venous thrombosis. No complications were associated with vena cava filter insertion. No patients developed deep venous thrombosis during their acute hospitalization (median, 22 d), and no patients have developed PE after filter insertion.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal fluid antibiotic levels during treatment of shunt infections.

Twenty patients with documented cerebrospinal fluid shunt infections were treated with daily intraventricular injections of methicillin, cephalothin, or gentamicin without removal of the shunt or external ventricular drainage. Periodic determinations of intraventricular antibiotic concentration revealed significant levels in relation to the established minimum inhibitory concentration in all cases.

Oral glycerol for the treatment of traumatic intracranial hypertension.

Hyperosmolar agents are a primary therapeutic modality employed in the treatment of traumatic intracranial hypertension. Profound hyperosmolarity accompanied by systemic dehydration is a potentially serious problem when these drugs are used repeatedly for control of intracranial pressure. Because glycerol, a water-soluble alcohol, is metabolized in the liver, its dehydrating capacity may be reduced in comparison to other agents. A series of 15 patients were treated with oral glycerol (0.5 to 1.0 gm/kg) with only minor changes in serum electrolytes, glucose, and urea nitrogen. Serum osmolarity rose from a baseline of 305 mOsm/liter to 355 mOsm/liter after 10 days of therapy. Glycerol was found to be effective and safe when employed in this protocol and proved to be a valuable adjunct to the standard methods available for control of intracranial hypertension.

Extradural spinal involvement by gout. Case report.

A case of extradural gouty tophus in the lumbar region in a teen-age girl is presented as an addition to the differential diagnosis of erosive lesions of the spinal canal.

Advances in the early management of patients with head injury.

The last decade has seen continual improvement in our skills of visualizing and diagnosing the many types of human head injury. As we continue to unravel the complex biochemistry and molecular changes caused by trauma, we expect to find new methods and agents to enhance the extracellular milieu of injured but salvageable neurons and supporting cells, resulting in continued improvement in outcome for patients with severe head injury.

Chronic or recurrent meningitis. Neurosurgical perspectives.

Chronic meningitis is not a commonly encountered clinical problem in the day-to-day patient care responsibilities of neurosurgeons. It is, however, important for the neurosurgeon to be familiar with the clinical problems, diagnostic challenges, and therapeutic options required to establish a definitive diagnosis. This article concentrates on specific entities causing chronic or recurrent meningitis that may require neurosurgical participation.

Cardiac surgery in patients over the age of 80 years.

The risk-benefit relationship of open heart surgery in octogenarians is not well established. Eighty consecutive patients over the age of 80 who underwent cardiac operations under cardiopulmonary bypass were evaluated. Twenty-five patients were in functional class IV, 42 in class III, and 13 in class II. Forty-four patients had only coronary artery bypass grafts (CABG), 12 only aortic valve replacement (AVR), 6 only mitral valve replacement (MVR), 12 CABG and AVR, 4 CABG and MVR, 1 CABG and aneurysmectomy, and 1 had resection of left atrial myxoma. Operative mortality (within 30 days) was 12.5% for the group. Mortality was related to bleeding, left ventricular failure, primary ventricular fibrillation, pulmonary failure, and renal failure. Mortality was higher in patients with (1) advanced functional class, (2) mitral valve replacement, (3) postoperative hemorrhage, and (4) associated pulmonary disease. While a generally conservative approach is recommended for octogenarian patients, many with life-threatening cardiac disease, especially those free of major multisystem illnesses, should not be denied the benefit of surgical treatment.

The effect of hypotension and hypoxia on children with severe head injuries.

Survival of children (< 17 years) with severe head injuries (Glascow Coma Scale [GCS] score < 8) has been shown to be better than that of adults. The addition of hypotension (HT) or hypoxia (H) has a deleterious effect on outcome in adults but no information is currently available about their effects in children. Over a 5-year period, 58 children with GCS scores < 8 were admitted and prospectively evaluated at this institution. Patients were divided into two groups on the basis of systolic blood pressure (SBP) and arterial blood gasses. Patients exhibiting HT, defined as a SBP < 90 mm Hg, and patients demonstrating H with a PaO2 < 60 mm Hg were compared with normoxic, normotensive children. Survival was increased fourfold in patients with neither H nor HT as compared with children with either H or HT (P < .001). To validate these observations we reviewed the data from the National Pediatric Trauma Registry for similar patients and included our cohort in the analysis. In total, 509 children had sufficient data for analysis and were studied. Hypoxia alone was not associated with increased mortality in normotensive patients (P = .34). Hypotension significantly increased mortality in these children even without concomitant H (P < .00001). If both HT and H were found together, mortality was only slightly increased over those children with HT alone (P = .056). These data confirm that HT with or without H causes significantly increased mortality in head-injured children to those levels normally found in adults (P = .9), alleviating any age-related protective mechanisms normally afforded.(ABSTRACT TRUNCATED AT 250 WORDS)

The epidemiology of injury in a rural state: 5,322 cases over 6 years.

Presently, descriptions of rural trauma are complications of national sample statistics and local data from states projected to rural areas. This study reviews all hospital discharges (36,866) for children (aged 0 to 18 years) from January 1985 through December 1990 in an entirely rural state. Fourteen percent of admissions (5,322) were due to traumatic injury and 63% of these occurred in boys. Injury rates were age dependent with children 15 to 18 years experiencing an incidence of 110/10,000; 10 to 14 years 55/10,000; 5 to 9 years 39/10,000; 1 to 4 years 35/10,000; and < 1 year 39.5/10,000. Mean age for the entire population was 11.4 +/- 5.7 years. Thirty-five percent of children had more than one major site of injury. Sixty-three percent of admissions were for blunt trauma and only 4.8% were penetrating. The remainder were due to burns, hanging, ingestion, and other toxic agents. Falls constituted the most prevalent cause of injury in this population occurring in 25.9%, motor vehicle accidents 22.9%, struck by an object 9.6%, suicide attempts 8.5%, poisoning 4.7%, fire 1.2%, drowning 0.7%, and farm machinery 0.3%. The vast majority of motor vehicle accidents involved the child as an operator or occupant of the vehicle. Less than 10% involved a pedestrian being struck and less than 5% involved a child being struck while on a bicycle. Less than 6% of all injuries involved a bicycle. Child maltreatment was recorded in less than 2% of this population. Only 3.3% of injured children required transfer to another acute care facility (1/3 because of a motor vehicle accident and 1/4 because of a fall).(ABSTRACT TRUNCATED AT 250 WORDS)

Sustained ventricular tachycardia associated with influenza syndrome in a young girl--a case report.

Ventricular arrhythmias in children with no demonstrable heart disease are rare. In a thirteen-year-old girl, a typical influenza syndrome was complicated by sustained ventricular tachycardia. Exercise tests, echocardiography, electrophysiological studies, and endomyocardial biopsy were negative. Viremia, fever, or medications may be responsible for this unusual complication.