Climate change as the dominant control on glacial-interglacial variations in C3 and C4 plant abundance

Although C4 plant expansions have been recognized in the late Miocene, identification of the underlying causes is complicated by the uncertainties associated with estimates of ancient precipitation, temperature, and partial pressure of atmospheric carbon dioxide (PCO2). Here we report the carbon isotopic compositions of leaf wax n-alkanes in lake sediment cores from two sites in Mesoamerica that have experienced contrasting moisture variations since the last glacial maximum. Opposite isotopic trends obtained from these two sites indicate that regional climate exerts a strong control on the relative abundance of C3 and C4 plants and that in the absence of favorable moisture and temperature conditions, low PCO2 alone is insufficient to drive an expansion of C4 plants.

Zwitterionic and acidic glycosphingolipids of the Drosophila melanogaster embryo

Defining glycosphingolipid structures in species amenable to genetic manipulation, such as Drosophila melanogaster, provides a foundation for investigating mechanisms that regulate glycolipid expression. Therefore, eight of the 12 major glycosphingolipids, accounting for 64% of lipid-linked carbohydrate in Drosophila embryos, were purified after separation into acidic and zwitterionic pools. The zwitterionic lipids possess phosphoethanolamine (PEtn) linked to one or more GlcNAc residues and comprise a family of serially related structures. The longest characterized glycolipid, an octaosylceramide, designated Nz28, has the structure: GalNAcbeta, 4(PEtn-6)GlcNAcbeta,3Galbeta,3GalNAcalpha,4Ga lNAcbeta, 4(PEtn-6)GlcNAcbeta,3Manbeta,4GlcbetaCer. Heptaosyl (Nz7), hexaosyl (Nz6), pentaosyl (Nz5) and tetraosyl (Nz4) forms of Nz28, sequentially truncated from the nonreducing terminus, possess only one PEtn moiety. The major acidic lipid, designated Az29, possesses two PEtn moieties and a glucuronic acid linked to a Gal-extended Nz28. Two other acidic glycolipids, Az9 and Az6, exhibit one PEtn moiety and the same hexose and N-acetylhexosamine composition as Az29 and Nz6, respectively. The fully extended Drosophila core oligosaccharide differs from that of other dipterans in the linkage at a single glycosidic bond, a distinction with significant structural and biosynthetic consequences. Furthermore, acidic species account for a larger proportion of total glycosphingolipid, and PEtn substitution of GlcNAc is more complete in the Drosophila embryo. Divergent characteristics may reflect interspecies variation or stage-specific glycosphingolipid expression in dipterans.

Surgical management of spinal cord compression from plexiform neurofibromas in patients with neurofibromatosis 1

OBJECTIVE

Plexiform neurofibromas with sizable intraspinal extensions and resultant spinal cord compromise pose challenging management problems, because these lesions may involve multiple nerves and engulf adjacent vascular and visceral structures. In this report, we review our experience with the surgical treatment of these lesions.

METHODS

Patients were identified by a detailed review of hospital medical records and the database of our multidisciplinary neurofibromatosis clinic. Ten patients had large plexiform neurofibromas that extended intraspinally, producing a combination of myelopathy and radiculopathy. Two patients exhibited single-level intraspinal growth, and eight showed multilevel involvement. Four patients showed bilateral plexiform neurofibromatous growth intraspinally, with "hourglass" compression of the spinal cord. Operative approaches and outcomes were reviewed in detail.

RESULTS

Gross total resection of the symptomatic intraspinal tumor component was achieved for nine patients. The management of the extraspinal component was individualized, depending on the pattern and extent of involvement of the surrounding structures. Nine patients experienced complete recovery of neurological function postoperatively; the remaining patient demonstrated significant functional improvement. With a median follow-up period of 4 years, only one patient has developed recurrent intraspinal compression, in this case from tumor involvement by the same plexiform lesion at a lower spinal level. Two patients treated early in the series using standard laminectomy approaches developed significant kyphotic deformities, necessitating subsequent fusion. Based on these initial results, osteoplastic laminotomy techniques were used in the last five cases, allowing anatomic reconstruction of the involved levels; none of these latter patients has developed significant kyphosis, with a median follow-up period of 3 years.

CONCLUSION

Radical resection of intraspinal tumor components in patients with neurofibromatosis 1 and large plexiform neurofibromas can help to preserve excellent neurological function. Technical factors in the management of these lesions are presented.

Implementation of computerized social work data base/assessments

The Department of Veterans Affairs, Social Work Service has designed, developed and implemented the Social Work Information Management System (SWIMS) which provides for the collection and reporting of both administrative and clinical information. This paper describes the implementation of one component of SWIMS, the automated Social Work Data Base/Assessment. The discussion details the implementation process and discusses issues encountered in the implementation of a computerized documentation system.

Osteoid osteoma: percutaneous excision using a CT-guided coaxial technique

OBJECTIVE

We describe a coaxial technique for percutaneous, CT-guided removal of osteoid osteoma in children.

SUBJECTS AND METHODS

The study included eight children aged 3 years to 15 years 9 months who had signs and symptoms of osteoid osteoma. The diagnoses were confirmed by CT scans. Seven of nine lesions were removed manually with a coaxial technique and a trephine. Power tools were added to the technique in the other two cases. Removal of the nidus was confirmed by postprocedural CT scans and by histologic examination.

RESULTS

All CT-guided excisions were technically successful, and only one minor complication occurred. One recurrence at 13 months was successfully treated percutaneously.

CONCLUSION

CT-guided coaxial removal of osteoid osteoma is a safe and effective treatment. Increasing experience and the use of power tools in selected cases helps to shorten the procedure.

Cell surface ligands for rotavirus: mouse intestinal glycolipids and synthetic carbohydrate analogs

Rotaviral binding to receptors on epithelial cells in the small intestine is thought to be a key event in the infection process and may be carbohydrate-mediated. Strain SA11 of rotavirus bound in vitro both to glycolipids isolated from mouse small intestine and to authentic glycolipids using thin layer chromatography overlay and microtiter well adsorption assays. Neutral mouse intestinal glycolipids which bound rotavirus were GA1 (Gal beta 1----3GalNAc beta 1---4Glc beta 1----4Glc beta 1----1-ceramide) and pentaosylceramides with terminal N-acetylgalactosamine, while acidic lipids which bound rotavirus included cholesterol 3-sulfate and two compounds termed bands 80 and 81. Digestion with ceramide glycanase suggested that bands 80 and 81 have lactosyl ceramide cores and an unidentified acidic moiety(s). No sialic-acid-containing glycolipids tested were active in viral binding. Band 81, which may have a ganglio core, bound rotavirus with greatest avidity, followed by GA1. Of authentic glycolipids assayed, only GA1 and GA2 (GalNAc beta 1----4Gal beta 1----4Glc beta 1----1-ceramide) displayed rotaviral binding. A phosphatidylethanolamide dipalmitoyl-containing neoglycolipid analog of GA2 bound rotavirus with avidity similar to native GA2. Substitution of beta 1----4-linked GlcNAc or beta 1----3-linked GalNAc for terminal GalNAc of GA2 neoglycolipid supported rotaviral binding, while other substitutions abrogated it. These findings suggest that a carbohydrate epitope similar to that of GA2 is sufficient for in vitro rotaviral binding, although binding may be enhanced by galactose and/or an acidic moiety in a secondary epitope.

Synthesis of the antibiotic cortalcerone from D-glucose using pyranose 2-oxidase and a novel fungal enzyme, aldos-2-ulose dehydratase

Using two enzymes purified from the white-rot fungus, Polyporus obtusus, 5% solutions of D-glucose have been quantitatively converted in vitro into D-arabino-hexos-2-ulose (D-glucosone) and subsequently into a compound having antimicrobial activity. The antibiotic has been shown by nuclear magnetic resonance and mass spectroscopy to be chemically identical to a previously described fungal metabolite known as cortalcerone. Based on kinetic analysis of the synthetic process, a pathway for the biosynthesis of cortalcerone is proposed, involving both chemical rearrangement and enzymically catalyzed steps. Two enzymes, pyranose 2-oxidase and a previously uncharacterized D-arabino-hexos-2-ulose-utilizing enzyme, may be sufficient for the biosynthesis of cortalcerone from glucose in vivo. The D-arabino-hexos-2-ulose-utilizing enzyme dehydrates certain aldosuloses and has been named aldos-2-ulose dehydratase. The enzyme, which appears to be a dimer of 95-kDa subunits, has been purified 450-fold. Additional properties of aldos-2-ulose dehydratase are described, including its apparent ability to catalyze two different steps in the proposed biosynthetic pathway for cortalcerone.

Carbohydrate ligands for endothelial-leukocyte adhesion molecule 1

The acute inflammatory response requires that circulating leukocytes bind to and penetrate the vascular wall to access the site of injury. Several receptors have been implicated in this interaction, including a family of putative carbohydrate-binding proteins. We report here the identification of an endogenous carbohydrate ligand for one of these receptors, endothelial-leukocyte adhesion molecule 1 (ELAM-1). Radiolabeled COS cells transfected with a plasmid containing the cDNA for ELAM-1 were used as probes to screen glycolipids extracted from human leukocytes. COS cells transfected with this plasmid adhered to a subset of sialylated glycolipids resolved on TLC plates or adsorbed on polyvinyl chloride microtiter wells. Adhesion to these glycolipids required calcium but was not inhibited by heparin, chondroitin sulfate, keratan sulfate, or yeast phosphomannan. Monosaccharide composition, linkage analysis, and fast atom bombardment mass spectrometry of the glycolipids indicate that the ligands for ELAM-1 are terminally sialylated lactosylceramides with a variable number of N-acetyllactosamine repeats and at least one fucosylated N-acetylglucosamine residue.

Thiol-containing cross-linking agent with enhanced steric hindrance

Ricin A chain immunotoxins disulfide cross-linked with conventional, sterically unhindered reagents have unsatisfactorily short circulating life times in vivo. (Acetylthio)succinic anhydride, a thiolating reagent with partial steric hindrance of the sulfur atom, does not remedy this situation. Sulfosuccinimidyl N-[3-(acetylthio)-3-methylbutyryl]-beta- alaninate, a new cross-linker in which the carbon alpha to the sulfur is doubly methylated, creates disulfide bonds 2 orders of magnitude more resistant to reduction than unhindered disulfides. Nevertheless, this deactivated thiolating agent rapidly and reliably cross-links ricin A chain and antibodies to create immunotoxins with in vitro cytotoxicities comparable to those of 2-iminothiolane-coupled conjugates.

Foot growth in children age one to five years

As part of the protocol on the Development of the Child's Arch, foot growth studies were monitored prospectively in 107 children from 1 year of age till 5 years of age. Under 15 months of age, growth necessitated a 1/2 size footwear change in less than 2 months; from 15 months to 2 years of age, 1/2 size increase occurred every 2 to 3 months; from 2 to 3 years of age, 1/2 size change every 3 to 4 months; and from 3 to 5 years of age, 1/2 size change every 4 months. Although foot growth in boys and girls is parallel, boys' feet tend to average one size longer and one size wider. Width growth remained proportional to length growth throughout the study.

Development of the child's arch

The purposes of the project were to monitor the development of the lower extremities and the longitudinal arch of the foot and to determine whether or not arch support footwear (three types) affected development of a neutral arch in toddlers 11 to 14 months of age until age 5 years. A total of 125 beginner walkers were recruited through the pediatrics department during a period of 1 1/2 years and divided by lot into four different footwear groups (one nonarch supportive). The group was studied for 4 years by physical examinations, x-ray films, and pedotopography (a Moire fringe technique of photography). At initial examination all of the apparently normal toddlers had pes planus by all clinical, roentgenographic, and photographic measurements. There were no cavus feet at that time or at 5 years of age. Arches developed regardless of the footwear worn but development was faster during the first 2 years (until age 3 years) with arch support footwear. The rapidity of arch development until 5 years of age continued in those children who wore longitudinal arch cookies. Ossification of the sustentaculum tali begins at approximately 5 years of age but is not complete for at least another 1 to 2 years. Hyperpronation was present in 77.9% and genu valgum in 92.3% of the 5-year-old children. These conditions are apparently the norm at this age in both boys and girls.

Bronchoscopic use of the neodymium-yttrium-aluminium-garnet laser for lesions of the trachea and bronchus

The neodymium-yttrium-aluminium-garnet laser has proved to be a useful therapeutic tool for the management of endobronchial lesions. Between October 1, 1986 and October 31, 1987, 31 patients received 41 laser treatments at the Peter MacCallum Cancer Institute mainly for bronchial obstruction, haemoptysis or persistent cough. Good symptomatic relief was obtained in the majority of patients with no operative mortality and a moderate morbidity. When the endobronchial lesion is malignant, concurrent radiotherapy is needed to prevent the early recurrence of the cancer.

DMSO is a substrate for chloroperoxidase

Dimethyl sulfoxide has been used as a nonaqueous organic solvent in haloperoxidase reactions. However, it has been found that this solvent is not inert under chloroperoxidase reaction conditions, forming the halosulfoxide, the sulfone, and the halosulfone. The biological significance of this finding is briefly discussed.

The effect of oxpentifylline ('Trental') on fibrinolytic activity and plasma fibrinogen levels

Twenty healthy volunteers were treated for 3 months with oxpenifylline (200 mg 3-times a day) or a placebo in a controlled double-blind randomized trial. The volunteers taking the oxpenifylline showed a significant increase in their fibrinolytic activity, as assessed by the dilute blood clot lysis time and fibrin plate lysis area, and a significant reduction in their plasma fibrinogen levels. No change was found in the control group. These findings suggest that oxpentifylline may be valuable in the treatment of small vessel occlusive disease associated with lowered fibrinolytic activity and raised fibrinogen levels.