Assessment of pseudarthrosis in pedicle screw fusion: a prospective study comparing plain radiographs, flexion/extension radiographs, CT scanning, and bone scintigraphy with operative findings

Tribal warfare is a way of life in the highlands of Papua New Guinea. In earlier times direct confrontation with bushknives and axes, and shooting with bows and arrows were common. In recent years there have not been as many instances of direct confrontation with bushknives and axes, but the use of bows and arrows is on the rise. Since 1993, guns have been increasingly used, with devastating results. In 1993, 18 deaths were reported from tribal warfare in one area of the Southern Highlands Province, especially from gunshots, while in 1994, 24 deaths were reported from another area. A five-year review of tribal fight admissions to Mendi Hospital, from 1990 to 1994, showed an increase in the number and proportion of gunshot wounds; there were none in 1990-1992 but they constituted 18% of tribal fight injuries in 1993 and 33% in 1994.     

Ex vivo staining of metastatic lymph nodes by class I major histocompatibility complex tetramers reveals high numbers of antigen-experienced tumor-specific cytolytic T lymphocytes

Characterization of cytolytic T lymphocyte (CTL) responses to tumor antigens has been impeded by a lack of direct assays of CTL activity. We have synthesized reagents ("tetramers") that specifically stain CTLs recognizing melanoma antigens. Tetramer staining of tumor-infiltrated lymph nodes ex vivo revealed high frequencies of tumor-specific CTLs which were antigen-experienced by surface phenotype. In vitro culture of lymph node cells with cytokines resulted in very large expansions of tumor-specific CTLs that were dependent on the presence of tumor cells in the lymph nodes. Tetramer-guided sorting by flow cytometer allowed isolation of melanoma-specific CTLs and confirmation of their specificity and their ability to lyse autologous tumor cells. Our results demonstrate the value of these novel reagents for monitoring tumor-specific CTL responses and for generating CTLs for adoptive immunotherapy. These data also indicate that strong CTL responses to melanoma often occur in vivo, and that the reactive CTLs have substantial proliferative and tumoricidal potential.     

A rate-splitting approach to the Gaussian multiple-access channel

It is shown that any point in the capacity region of a Gaussian multiple-access channel is achievable by single-user coding without requiring synchronization among users, provided that each user “splits” data and signal into two parts. Based on this result, a new multiple-access technique called rate-splitting multiple accessing (RSMA) is proposed. RSMA is a code-division multiple-access scheme for the M-user Gaussian multiple-access channel for which the effort of finding the codes for the M users, of encoding, and of decoding is that of at most 2M-1 independent point-to-point Gaussian channels. The effects of bursty sources, multipath fading, and inter-cell interference are discussed and directions for further research are indicated     

Metabolic studies on haloperidol and its tetrahydropyridine analog in C57BL/6 mice

The neuroleptic agent haloperidol (HP) is biotransformed in humans to a pyridinium metabolite, HPP+, that displays neurotoxic properties resembling those of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-derived neurotoxic pyridinium metabolite MPP+. We report here that HP and its tetrahydropyridine dehydration product 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]-1,2,3,6- tetrahydropyridine (HPTP) are metabolized in vivo by the MPTP-susceptible C57BL/6 mouse to several pyridinium metabolites including HPP+ and the 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-hydroxybutyl]pyridinium species RHPP+, the pyridinium species corresponding to reduced haloperidol (RHP), a major circulating metabolite of HP. Atmospheric pressure ion-spray (API) mass spectral data also suggest the formation of fluorophenyl ring-hydroxylated derivatives of these two pyridinium metabolites. Furthermore, HPLC tracings reveal the presence of HPP+, RHPP+, and two phenolic pyridinium metabolites in brain tissue extracts of HPTP, but not HP, treated mice. The neurotoxic potential of MPTP-type pyridinium species suggests that these metabolites may contribute to some of the neurological disorders observed in humans undergoing chronic HP treatment.     

Acute, severe cardiomyopathy as main symptom of late-onset very long-chain acyl-coenzyme A dehydrogenase deficiency

A 5-year-old boy with late-onset very long-chain acyl-CoA-dehydrogenase (VLCAD) deficiency presented with acute cardiomyopathy, myopathy, gross myoglobinuria and normoglycaemia. The clinical course after diagnosis was favourable. CONCLUSION: late-onset VLCAD deficiency may present as acute cardiomyopathy.     

Phosphonates Meet Metal−Organic Frameworks: Towards CO2 Adsorption

Here we report a new highly microporous zirconium phosphonate material synthesized under solvothemal conditions. The specific Brunauer-Emmett-Teller (BET) surface area of the “unconventional metal−organic framework” (UMOF) is measured to be ∼900 m²/g, after following an appropriate activation protocol. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) shows that the material bears a free −OH functionality on the phosphonate linker that may interact with CO₂. CO₂ adsorption isotherms were collected and a measured heat of adsorption of 31 kJ/mol was obtained. In addition, adsorption isotherms of CO₂, N₂, and CH₄ at 298 K combined with Ideal Adsorbed Solution Theory (IAST) show that the material can be expected to display high selectivities for uptake of CO₂ versus N₂ or CH₄.     

Pedicle screw fixation for arthrodesis of the lumbosacral spine in the elderly. An outcome study

STUDY DESIGN: An analysis of the outcome and effectiveness of instrumented arthrodesis of the lumbosacral spine in elderly patients conducted using a review of records, assessment of fusion via plain radiographs, and a two-part questionnaire. OBJECTIVE: To ascertain the outcome and efficacy of instrumented arthrodesis of the lumbosacral spine in patients 60 years of age and older. BACKGROUND DATA: From 1987 to 1991, 38 patients of at least 60 years of age underwent instrumented arthrodesis of the lumbosacral spine using the Wiltse or Selby pedicle screw fixation system (Advanced Spine Fixation Systems, Inc., Irvine, CA). Patients were considered for surgery only after attempts at conservative management, including physical therapy, medication, injection blocks, and home exercises, had proven unsuccessful. METHODS: Follow-up examinations were performed 3 months, 6 months, 1 year, and 2 years after surgery. Fusion was assessed using plain radiographs, including flexion-extension films. Inpatient and outpatient records were reviewed, and a two-part questionnaire was used to establish the effect of surgery on function and lifestyle. Thirty patients responded to the questionnaire. Follow-up observation of the patients ranged from 25 to 56 months. The mean age was 73.8 years (range, 60-90 years). RESULTS: The mean co-morbidity was 1.7. Based on the authors' method of evaluation of fusion, the fusion rate was 92%. Fifty-seven percent of the patients reported excellent or good results, 26% reported fair results, and 17% reported poor results. Functional gains of 50% or more were reported by 71% of the respondents. Female patients had significantly more complications than male patients, but reported comparable outcomes. CONCLUSION: Despite the increase in age, co-morbidity, and associated risk of perioperative complications inherent in this population, an outcome comparable with that of younger patients is reported.     

Hepatic Δ9, Δ6, and Δ5 desaturations in non-insulin-dependent diabetes mellitus eSS rats

Both diabetes mellitus type 1 and diabetes mellitus type 2 are widespread diseases that alter carbohydrate and lipid metabolism. e Stilmann-Salgado (eSS) rats are experimental animals that spontaneously evolve to a state similar to that of young people affected by non-insulin-dependent diabetes mellitus (NIDDM; type 2). Using 6-mon-old eSS rats that, according to the literature [Martinez, S.M., Tarrés, M.C., Montenegro, S, Milo, R., Picena, J.C., Figueroa, N., and Rabasa, S.R. (1988) Spontaneous Diabetes in eSS Rats, Acta Diabetol. Lat. 25, 303–313], had already developed insulin resistance, we investigated the changes evoked on Δ9, Δ6, and Δ5 liver desaturases. The abundance of mRNA and enzymatic activities were measured, as well as the FA composition of liver microsomal lipids. Compared to control rats, the mRNA content and activity of SCD-1 (stearoyl CoA-desaturase, isoform of the Δ9 desaturase) were significantly higher, urase, isoform of the Δ9 desaturase) were significantly higher, whereas the mRNA and activities of Δ6 and Δ5 desaturases were not significantly modified. Correspondingly, the proportion of 18∶1n−9 and the ratios of 18∶1n−9/18∶0 and 16∶1/16∶0 in lipids were significantly increased, whereas the proportion of 20∶4n−6 was unaltered. These effects were found while glycemia was constant or increased. The results are completely opposite those described in insulin-dependent diabetes mellitus (type 1), in which a depression of all the desaturases is found. They suggest that in eSS rats, the activities of the desaturases were not modified by an insulin-resistance effect. Moreover, we suggest that the enhancement of SCD-1 activity might be considered as another typical sign of the NIDDM syndrome, because it has also been found in other animal models of NIDDM, for example, the ones evoked by the sucrose-rich diet and in the Zucker rat.     

Generalized time sharing: a low-complexity capacity-achievingmultiple-access technique

It is shown that the encoding/decoding problem for any asynchronous M-user memoryless multiple-access channel (MAC) can be reduced to corresponding problems for at most 2M-1 single-user memoryless channels. This is done via a method called generalized time sharing that is closely related to a previously developed method called rate-splitting multiple access. These methods reduce the seemingly hard task of finding good multiple-access codes and implementable decoders for such codes to the much better understood task of finding codes and decoders for single-user channels. As a by-product, some interesting properties of the capacity region of M-user asynchronous discrete memoryless channels are derived     

Rate-distortion theory applied to automatic object recognition

We consider the problem of recognizing CAD models at arbitrary orientations observed via the projective transformation on an imaging sensor with noise. Bounds on codebook size are established through the rate-distortion curve for a distortion measure derived from the Hilbert-Schmidt norm for elements of the orthogonal group