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Biomedical subjects

J W Reed

Publications and source records attributed to J W Reed.

At least 73 records · Page 4Linked to original sources
PubMed1990

Genetic analyses of Rhizobium meliloti exopolysaccharides.

We have recently obtained strong genetic evidence that the acidic Calcofluor-binding exopolysaccharide (EPS I) of Rhizobium meliloti Rm1021 is required for nodule invasion and possibly for later events in nodule development. Thirteen loci on the second megaplasmid have been identified that are required for, or affect, the synthesis of EPS I. Mutations in certain of these loci completely abolish the production of EPS I and result in mutants that form empty Fix- nodules. exoH mutants fail to succinylate their EPS I and form empty Fix- nodules. We have identified two unlinked regulatory loci, exoR and exoS, whose products play negative roles in the regulation of expression of the exo genes. We have recently discovered that R. meliloti has a latent capacity to synthesize a second exopolysaccharide (EPS II) that can substitute for the role(s) of EPS I in nodulation of alfalfa but not of other hosts. Possible roles for Rhizobium exopolysaccharides in nodulation are discussed.

Carbohydrate Sequence↗
PubMed1989

Penetrating keratoplasty for herpes zoster keratopathy.

We reviewed retrospectively the records of 12 patients with herpes zoster keratopathy who had undergone penetrating keratoplasty. Preoperatively, seven patients (58%) had noninflamed eyes with visually significant corneal scarring or edema. Five patients (42%) had progressive neurotrophic corneal ulceration, and four of those had corneal perforation. Tarsorrhaphies were placed in ten patients and appeared to be beneficial in preventing postoperative breakdown of the corneal surface. At an average follow-up time of 36 months, ten of the 12 grafts (83%) remained clear, with nine patients (75%) having a visual acuity of 20/80 or better.

Aged↗
PubMed1989

Hypertensive therapy for diabetic patients.

The treatment of patients with both diabetes mellitus and hypertension must take into account the increased risk of vascular complications. If an adequate trial of non-pharmacological therapy does not prove effective, drug therapy, tailored to the individual patient, is instituted. In this event, monotherapy should be the primary goal.

Diabetes Complications↗
PubMed1988

Genetic analysis of a cluster of genes required for synthesis of the calcofluor-binding exopolysaccharide of Rhizobium meliloti.

Rhizobium meliloti produces an acidic, Calcofluor-binding exopolysaccharide which plays a role in nodulation of alfalfa plants by this bacterium. We constructed and mapped 102 transposon insertions in a 48-kilobase (kb) region previously shown to contain several exo genes. Mutations affecting production of the Calcofluor-binding exopolysaccharide were clustered in a 22-kb region and fell into 12 complementation groups. Strains carrying mutations in seven of the complementation groups (exoA, exoB, exoF, exoL, exoM, exoP, and exoQ) produced no Calcofluor-binding exopolysaccharide and induced non-nitrogen-fixing nodules on alfalfa. Mutants in an eighth complementation group, exoH (Leigh et al., Cell 51:579-587, 1987), produce an altered exopolysaccharide and also induce the formation of non-nitrogen-fixing nodules. Mutants in the remaining four complementation groups produced less Calcofluor-binding material than the wild type. Mutants carrying mutations in two of these complementation groups (exoK and exoN) formed apparently normal, nitrogen-fixing nodules, while mutants in the other two groups (exoG and exoJ) formed normal nodules less efficiently than the wild type.

Benzenesulfonates↗
PubMed1988

Indirect estimation of maximal oxygen uptake for study of working populations.

A total of 345 shipyard workers (aged 23 to 47) volunteered to perform progressive exercise on a cycle ergometer (15 W/min increments) up to the symptom limited maximum. The results were used to obtain maximal oxygen uptake (nO2 max), the oxygen uptake at a respiratory exchange ratio of unity (nO2 at R1.0), and cardiac frequency at an oxygen uptake of 45 mmol/min (fC45). In this group 156 men (45% of initial population) attained nO2 max as defined, 108 (31%) withdrew or did not exercise maximally, and 49 (14%) had transient electrocardiographic abnormalities. For the 156 men extrapolation of the relation of cardiac frequency on oxygen uptake to the predicted maximal cardiac frequency resulted in overestimation of nO2 max by 9.6%. nO2 Max per kg body mass was negatively correlated with body mass. nO2 Max (mean value 130.6 mmol/min) was described in terms of age, fat free mass, smoking (yes or no), and level of habitual activity (rated 1 to 4): the standard error of the estimate (SEE) was 17.3 mmol/min (R2 0.42); the equation was suitable for reference values. For estimating the nO2 max of individual men an empirical relation based on nO2 at R1.0, fC45, fat free mass, and % body fat had an SEE of 12.1 mmol/min (R2 0.67). Seventy six per cent of men (88% of those who exercised) attained nO2 at R1.0 (oxygen uptake approximately 73% of maximum). Thus the nO2 max could be estimated in a higher proportion of men than could achieve nO2 max. The estimate is appropriate for assessing exercise capacity in relation to employment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Calculation of whole blood CO2 content.

Currently used methods for calculating whole blood CO2 content from calculated plasma content, measured blood pH, hemoglobin concentration ([Hb]), and O2 saturation yield materially different results. In this study the constants of the fundamental equations relating blood CO2 content to plasma content have been reevaluated. An iterative computer technique was used to empirically derive appropriate constants from data obtained from nine healthy male subjects at rest and at several exercise work loads. A calculation was derived that fitted the data well [difference 0.02 +/- 1.19 ml/100 (SD) ml, r = 0.98] blood CCO2 = plasma CCO2 (Formula: see text) where plasma CCO2 = 2.226.s.plasma PCO2.(1 + 10pH-pK'), CCO2 is CO2 content, SO2 is O2 saturation, s is the plasma CO2 solubility coefficient, and pK' is the apparent pK [s and pK' are from the equations of Kelman (Respir. Physiol. 3: 111-115, 1967)].

Adult↗
PubMed1988

Elimination of monocular diplopia by corneal tattooing.

Corneal tattooing to eliminate monocular diplopia secondary to surgical peripheral iris defects was performed successfully in two patients who were unable to tolerate contact lenses. The technique is simple, safe, cosmetically satisfactory, and eliminates the need for patient compliance with contact lens care. Although corneal tattooing is usually considered to have only cosmetic value, these patients demonstrate that it can be therapeutic as well.

Aged↗
PubMed1987

Rhizobium meliloti mutants that fail to succinylate their calcofluor-binding exopolysaccharide are defective in nodule invasion.

We have identified a set of Tn5-generated mutants of Rhizobium meliloti on the basis of their failure to form a fluorescent halo under UV light when grown on agar medium containing Calcofluor. These mutations define a new genetic locus we have termed exoH. Alfalfa seedlings inoculated with exoH mutants form ineffective nodules that do not contain intracellular bacteria or bacteroids. Root hair curling is significantly delayed and infection threads abort in the nodule cortex. Analyses of exopolysaccharide secreted by exoH mutants have shown that it is identical to the Calcofluor-binding exopolysaccharide secreted by the exoH+ parental strain except for the fact that it completely lacks the succinyl modification. In vitro translation of total RNA isolated from nodules induced by an exoH mutant has shown that only one of the plant-encoded nodulins is induced, as compared with the 17 nodulins induced by wild-type strains. These observations suggest that succinylation of the bacterial polysaccharide is important for its role(s) in nodule invasion and possibly nodule development.

DNA Transposable Elements↗
PubMed1987

Respiratory effects of a single saturation dive to 300 m.

Lung function and the response to exercise were monitored in seven diver/welders who took part in a test saturation dive to 300 m for an average duration of 12 days; decompression took an average of nine days. Immediately after the dive the forced vital capacity was increased above base line by on average 0.51, the forced expiratory volume by 0.281 and peak expiratory flow rate by 0.71 s-1. There was no change in flow rate at small lung volumes (FEF 75% FVC). Recovery was complete and appeared to have a half time of 28 days. Transfer factor of the lungs for carbon monoxide (TlCO) was reduced by on average 9.6% after the dive but while partial recovery occurred, the values at one year were on average lower than those observed initially. The reason is unclear. One subject developed transient oxygen toxicity with stiff lungs and increased ventilation and cardiac frequency during submaximal exercise; a second subject developed similar changes but without accompanying symptoms. There is need for detailed physiological surveillance of people undertaking deep dives; this should be undertaken in circumstances that permit accurate measurements and full subject cooperation.

Adult↗
PubMed1986

Glaucoma management in pseudophakia.

The ever-increasing number of cataract extractions followed by insertion of intraocular lenses has resulted in the emergence of a new group of patients with severe glaucoma. A series of 41 patients (45 eyes) referred for evaluation and management of uncontrolled glaucoma in pseudophakia is presented. Glaucoma had preexisted in 23 eyes. Sixteen different mechanisms were responsible for the postoperative glaucoma. Among the 41 patients were three with acquired pigmentary glaucoma. The case report of one of those three demonstrates that nonfixation of an Anis posterior chamber intraocular lens was the means by which iris pigment was dislodged. In all cases medical therapy was instituted or intensified, but resulted in acceptable glaucoma control in only 14 eyes. Laser procedures were used in 24 eyes, and laser therapy followed by medical therapy resulted in control in 19 eyes. The remaining 12 eyes underwent 31 surgical procedures, including three enucleations.

Aged↗
PubMed1984

Relationship of ventilatory capacity to hyperbaric exposure in divers.

The results of divers' annual medical examinations were used to assess the effects of diving exposure independent of age, stature, and smoking on forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). Cross-sectional analysis of records for 858 men showed a significant positive association between the maximal depth that subjects had experienced and FVC but not FEV1. There was a significant negative association for FEV1/FVC%, and this index was also positively correlated with years of diving exposure. Among a subsample of 81 men the forced expiratory flow rate at low lung volume was reduced relative to that of control subjects similarly assessed; the extent of the reduction from the reference value was significantly correlated with the diving exposure. Longitudinal analysis of results for 255 men over a minimum of 5 yr showed that the change in FVC per annum (positive or negative) was correlated with the change in maximal depth; there were no similar associations for FEV1 or FEV1/FVC%. Thus diving exposure affects the vital capacity and the forced expiratory flow rate at small lung volumes. The latter is evidence for narrowing of airways that might be secondary to diving-induced loss of lung elastic tissue; this hypothesis merits further investigation.

Adult↗