Alginate production by plant-pathogenic pseudomonads

Eighteen plant-pathogenic and three non-plant-pathogenic pseudomonads were tested for the ability to produce alginic acid as an exopolysaccharide in vitro. Alginate production was demonstrated for 10 of 13 fluorescent plant-pathogenic pseudomonads tested with glucose or gluconate as the carbon source, but not for all 5 nonfluorescent plant pathogens and all 3 non-plant pathogens tested. With sucrose as the carbon source, some strains produced alginate while others produced both polyfructan (levan) and alginate. Alginates ranged from <1 to 28% guluronic acid, were acetylated, and had number-average molecular weights of 11.3 x 10 to 47.1 x 10. Polyfructans and alginates were not elicitors of the soybean phytoalexin glyceollin when applied to wounded cotyledon surfaces and did not induce prolonged water soaking of soybean leaf tissues. All or most pseudomonads in rRNA-DNA homology group I may be capable of synthesizing alginate as an exopolysaccharide.

Diffuse unilateral hemorrhagic retinopathy associated with accidental perinatal strangulation. A clinicopathologic report

OBJECTIVE

To report an unusual case of diffuse retinal hemorrhage associated with strangulation in a neonate with a tightly wrapped nuchal cord around his neck at birth who was noted to have eyelid and subconjunctival petechial hemorrhages upon delivery.

METHODS

Clinical diagnostic examination as well as postmortem gross and histopathologic examination of ocular and central nervous system structures was performed.

RESULTS

Funduscopic and gross pathologic examination of the eyes revealed extensive unilateral retinal hemorrhage of the right eye only. This was corroborated by histopathologic studies, which revealed unilateral diffuse hemorrhage throughout all nuclear layers of the retina with a particularly dense nerve fiber layer and sub-internal limiting membrane hemorrhage in the macula along with extraocular muscle and episcleral hemorrhage. Clinical, gross, and microscopic examination also revealed multiple areas of hemorrhage involving the right side of the brain and throughout the cerebellum.

CONCLUSION

Although retinal findings in nonaccidental trauma are common, accidental strangulation retinopathy in neonates is a rare occurrence. To the authors' knowledge, this case is the only documented histopathologic study of hemorrhagic retinopathy associated with strangulation in the literature.

Solvent effects on the molecular properties of pectins

Measurements revealed that LiAc/HAc buffer, when compared with other solvents, gave relatively low values of turbidity for five commercial pectins with various apparent molar masses and degrees of methyl esterification (DE). Therefore, HPSEC with on-line light scattering and viscosity detection was employed to compare LiAc/HAc buffer against NaNO(3) solution, a commonly used mobile phase for measuring the molecular properties of these pectins and an additional pectin prepared by microwave extraction. Microwave-extracted pectin was included in the study for its higher molar mass and DE compared with commercial pectins. Most commercial samples were more soluble and had a higher molar mass when dissolved in NaNO(3) than in LiAc/HAc buffer, whereas the microwave-extracted pectin was more soluble in LiAc/HAc buffer and had about the same molar mass. Furthermore, association fragments of pectin contained in samples were more dissociated by LiAc/HAc buffer than by NaNO(3). For the samples studied, weight-average molar masses ranged from about 41000 to 307000, weight-average intrinsic viscosities from about 0.86 to 9.76 dL/g, z-average radii of gyration from about 13 to 45 nm, and Mark-Houwink constants from about 0.62 to 0.94.

Characterization of pectin, flash-extracted from orange albedo by microwave heating, under pressure

Pectin was acid extracted from orange albedo by microwave heating under pressure. Extraction times ranged from 2.5 to 8 min. Solubilized pectin was characterized for molar mass (M), rms radius of gyration (Rg) and intrinsic viscosity [eta] by HPSEC with online light scattering and viscosity detection. M, Rg and [eta] all decreased with increasing extraction time. Nevertheless, at heating times of 2.5 and 3.0 min, M, Rg and [eta] were significantly higher than a commercial citrus pectin when the albedo:solvent ratio was 1:25 (w/v). At the heating time of 2.5 min Mw was 3.6 x 10(5), Rgz was 38 nm and [eta]w was 10.8 dL/g. Chromatography revealed that solubilized pectin distributions were bimodal in nature and that the low-molar-mass fraction increased at the expense of the high-molar-mass fraction with increasing extraction time. Scaling law exponents revealed that the high-molar-mass fraction was extremely compact in shape, whereas the low-molar-mass fraction was more asymmetric in shape. Possibly these results indicated that at short extraction times, pectin was solubilized as compact aggregated network structures that were broken down to their more asymmetric components with increased heating times.

Progressive dissociation of pectin

The structural organization of alkaline soluble peach pectin was investigated over size ranges extending from micrometers to tenths of nanometers. Analysis was by electron microscopy and high-performance anion-exchange chromatography (HPAEC). Superimposed and individual circular microgels in the micrometer size range were isolated from mesocarp tissue of cell walls and visualized by rotary shadowing. Dilute NaCl and 50% aqueous glycerol disaggregated these microgels into rods, segmented rods, and kinked rods, which collectively comprised the internal gel network of the microgels. Image analysis of the shadowed specimens before and after disaggregation followed by curve fitting of the smoothed distributions revealed a multimodal distribution of lengths. HPAEC revealed that the multimodal aggregates were stable for the most part to further dissociation by increasing ionic strength.

Treatment centers--the next challenge. The Counterpoint Unit at CPC Parkwood Hospital

Treatments centers have traditionally concentrated on the treatment of alcohol and various other chemical dependencies, frequently omitting treatment for nicotine dependence. Many have felt it to be too much to take away everything at once. Professionals in the treatment community are realizing more and more that nicotine dependence is another manifestation of the disease of addiction. Our philosophy challenges the old adage "don't take everything away at once," by addressing the issue of nicotine dependence. We began implementation of a nicotine-free unit at CPC Parkwood Hospital in November 1989. We are currently in the process of adopting a nicotine-free policy at Ridgeview Institute in Smyrna, Georgia. This article traces the evolution of a nicotine-free unit at CPC Parkwood Hospital.

Pectin microgels and their subunit structure

High-performance size exclusion chromatography revealed that alkaline-extracted peach fruit pectin dissolved in 0.05 M NaNO3 comprised a hierarchy of at least four aggregated, macromolecular-sized species. Each of the three largest species was found to be comparable in length to the three smallest subunits of an interconnecting gel network visualized by transmission electron microscopy of pectin, rapidly dried from solution. The interconnecting subunits of the gel network were rods or segmented rods and the integrated network formed a circular gel about 1 micron in diameter. Shadowed samples prepared from 5 and 50 mM NaCl or aqueous glycerol solutions produced images of partially dissociated subunits.

Macromolecular components of tomato fruit pectin

Chelate and alkaline-soluble pectin extracted from cell walls of pericarp tissue from mature green, turning, and red ripe (Lycopersicon esculentum Mill.) fruit (cv. Rutgers), were studied by high-performance size-exclusion chromatography. Computer-aided curve fitting of the chromatograms to a series of Gaussian-shaped components revealed that pectin from all fractions was composed of a linear combination of five macromolecular-sized species. The relative sizes of these macromolecules as obtained from their radii of gyration were 1:2:4:8:16. Dialysis against 0.05 M NaCl induced partial dissociation of the biopolymers. Apparently, the weight fraction of smaller sized species increased at the expense of larger ones. Also, the dissociation produced low-molecular-weight fragments. Behavior in the presence of 0.05 M NaCl led to the conclusion that cell wall pectin acted as if it were an aggregated mosaic, held together at least partially through noncovalent interactions.

Exopolysaccharides of the phytopathogen Pseudomonas syringae pv. glycinea

Exopolysaccharides (EPS) of the soybean pathogen Pseudomonas syringae pv. glycinea were isolated from culture filtrates and infected soybean leaves. Levan (a polyfructan with a C-2----C-6 backbone and C-2----C-1 branching) or acetylated alginate (a linear polyuronide of C-1----C-4-linked mannuronic and guluronic acids) was isolated from culture filtrates when bacterial strains were grown in a semisynthetic medium containing sucrose or glucose, respectively, as the primary carbon source. Acetylated alginate was the only EPS isolated from soybean [Glycine max (L.) Merr.] leaves inoculated with compatible (disease-inducing) strains of P. syringae pv. glycinea. The acetyl content of the P. syringae pv. glycinea alginates varied from 3 to 14%, and the amount of guluronic acid varied from less than 1 to 20%. The P. syringae pv. glycinea alginates from in vitro batch cultures were of lower molecular weight and polydispersity than those from in planta cultures, and both were of lower molecular weights than alginates produced by Pseudomonas aeruginosa.

Mallory-Weiss tear. A complication of cancer chemotherapy

Since the original report by Mallory and Weiss of tears in the lower esophagus or cardia of the stomach following alcoholic debauch, there have been many other cases, associated with sundry other causes, described in the literature. Recently, a Mallory-Weiss tear was reported in a patient as a complication of cancer chemotherapy. This article describes two similar cases and suggests that the Mallory-Weiss syndrome should be included in the differential diagnosis of any patient with epigastric pain, hematemesis, or melena after chemotherapy-induced retching or vomiting.

The ocular manifestations of Wegener's granulomatosis. Fifteen years experience and review of the literature

Ocular manifestations of Wegener's granulomatosis may occur secondary to contiguous granulomatous sinusitis or as a result of focal vasculitis. Contiguous granulomatous sinus disease causes nasolacrimal duct obstruction, proptosis and ocular muscle or optic nerve involvement. Focal vasculitis unrelated to contiguous upper respiratory tract disease is manifested by conjunctivitis, episcleritis, scleritis, corneoscleral ulceration, uveitis, and granulomatous vasculitis of the retina and optic nerve. A review of 29 cases of Wegener's granulomatosis and three cases of lymphomatoid granulomatosis studied over the past 15 years at the National Institute of Allergy and Infectious Diseases (NIAID) disclosed single or multiple ocular manifestations of disease in 15 patients (47 per cent). The pattern of ocular disease, its relationship to systemic involvement, diagnostic methods and the response to therapy are discussed.

Optic atrophy following prophylactic chemotherapy and cranial radiation for acute lymphocytic leukemia

Two patients with acute lymphocytic leukemia developed progressive optic nerve and chiasmal lesions eight to nine months after the initiation of identical chemotherapy protocols that included intrathecal medication and prophylactic radiation of only 2,400 rads to the central nervous system. Both patients eventually lost all vision despite additional radiotherapy, and there was no evidence of leukemia involving the central nervous system after acute lymphocytic leukemia was diagnosed. Optic nerve biopsy in one case showed changes consistent with radiation necrosis.

Intraocular irrigating solutions and lens clarity

By in vitro incubation of rhesus monkey lenses at 37degreesC, we determined that solutions superior to intraocular irrigating solutions in common clinical use could be prepared by aspetically adding commerically available solutions of dextrose 5% in water and sodium bicarbonate to either Ringer's injection or Ringer's lactate solutions. While not as effective as glutathione-bicarbonate-Ringer's solution (G-B-R) in maintaining lens clarity, these mixtures can be prepared easily in the operating room (in contrast to G-B-r) and may improve surgical results in procedures requiring prolonged intraocular irrigation.

Optic nerve metastasis from a mediastinal carcinoid tumour

A 25-year-old man with a rapidly progressive metastatic carcinoid tumour arising in the mediastinum developed a metastasis to the optic nerve. This is the first instance in the literature of an ocular metastasis from this variant of carcinoid tumour. The ocular pathology, ultrastructure, and recent information on the derivation of this tumour, believed to originate in the thymus, are presented.

Malignant melanoma of the skin metastatic to the eye. Frequency in autopsy series

Results of histopathologic examination of the eyes of 15 consecutive patients with metastatic malignant melanoma arising in the skin demonstrated evidence of intraocular metastasis in five patients. The metastases were microscopic, epithelioid, minimally pigmented, and occurred in both the choroid and the retina. All patients were asymptomatic. Those patients with ocular metastases all had primary malignant neoplasms of the superficial, spreading variety and associated central nervous system metastases.

Demonstration of macrophage chemotactic factors in the aqueous humor during experimental immunogenic uveitis in rabbits

Factors in the queous humor capable of increasing the random migration and chemotaxis of monocytes were demonstrated during experimental uveitis in the rabbit. Injection of endotoxin-free human serum albumin into the vitreous produced a severe inflammation detectable after 7 days and maximal between 12 to 21 days. Aqueous humor was measured for chemotactic activity with a modified Boyden chamber, which permitted the use of volumes of less than 0.025 ml. Chematactic activity was measurable during the primary inflammation and remained elevated for a short period of time after clinical inflammation and anterior chamber cellular reaction had decreased. A severe reinduction uveitis could be initiated by the intravenous injection of human serum albumin after day 30. Chemotactic factors could be measured at high titers by 8 h after this intravenous challenge.