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Biomedical subjects

J W Reed

Publications and source records attributed to J W Reed.

At least 55 records · Page 3Linked to original sources
PubMed1994

Cataract formation and cataract extraction after penetrating keratoplasty.

PURPOSE: This retrospective study was done to identify risk factors for cataract formation and cataract extraction after penetrating keratoplasty to determine whether a combined procedure (simultaneous cataract extraction with keratoplasty) or penetrating keratoplasty alone should be performed. METHODS: Variables from 342 phakic eyes having undergone penetrating keratoplasties were studied with univariate and multivariate analyses, including diagnosis, race, sex, age, preoperative lens opacities, preoperative vision, and length of follow-up. RESULTS: For cataract formation, age was the only independent risk factor found by multivariate analysis (P = 0.0001). For cataract extraction after penetrating keratoplasty, independent risk factors included age, sex, diagnosis, and preoperative lens opacities (P < or = 0.03). For example, the probability of a 65-year-old patient with Fuchs dystrophy requiring a cataract extraction within 5 years of keratoplasty is 81%. CONCLUSION: The likelihood of cataract formation and cataract extraction subsequent to penetrating keratoplasty increases greatly after 50 years of age, regardless of the diagnosis leading to the need for keratoplasty. The need for cataract extraction also is increased for female patients, for patients with Fuchs dystrophy, and for those with early preoperative lens opacity.

Adolescent↗
PubMed1994

Corneal tattooing to reduce glare in cases of traumatic iris loss.

The traumatic loss of iris is often associated with symptoms of glare, which can be debilitating. This symptom may be benefitted by wearing a contact lens with a clear, central optical zone and opacification of the remainder. The patient who is contact lens-intolerant may be helped by tattooing of all of the cornea except the central visual axis. Four patients who had traumatic iris loss and who were treated by this technique reported reduced glare as well as improvement in the cosmetic appearance of the eye. Although corneal tattooing is an ancient procedure, it continues to be of benefit for selected patients.

Adult↗
PubMed1994

The effects of a peripherally selective alpha 2-adrenoceptor antagonist, MK-467, on the metabolic and cardiovascular response to exercise in healthy man.

1. A double-blind, placebo controlled study has been conducted to investigate the consequences of i.v. treatment with MK-467, a peripherally selective alpha 2-adrenoceptor antagonist in exercising healthy male subjects. In particular, the effects on blood pressure, heart rate, circulating catecholamines (noradrenaline (NA) and adrenaline (A)), insulin, glucose and free fatty acids (FFA) were determined. 2. Exercise produced increases in catecholamines, blood pressure and heart rate. FFA increased at the start of the exercise but then declined as exercise progressed. 3. MK-467 significantly increased NA, in a dose-dependent manner, before and during exercise without altering A. Blood pressure and heart rate were not affected by drug treatment. 4. The insulin and FFA response to exercise was significantly enhanced by MK-467 although glucose was unaltered by drug. 5. It is concluded that both pre- and post-junctional peripheral alpha 2-receptors play an important role in the metabolic response to exercise in man.

Adrenergic alpha-Antagonists↗
PubMed1994

Experience of a standardised method for assessing respiratory disability.

A standardised method of scoring respiratory disability based on measurement and/or estimation of maximal oxygen uptake has recently been developed by the European Society for Clinical Respiratory Physiology. In the present study, we wanted to determine how the results obtained using this objective method compared with those by the more traditional empirical method used in a Medical Boarding Centre (MBC) for Respiratory Diseases. The subjects were 62 men who were claiming industrial injuries benefit on account of prior exposure to a respiratory hazard. The MBC ratings and the disability scores were correlated and, in the case of men with moderate or severe disability, numerically equivalent. The results provided independent confirmation that the MBC ratings were influenced by the forced expiratory volume, radiological category of pneumoconiosis and grade of breathlessness. In subjects in whom the measured and estimated maximal oxygen uptakes were inconsistent, the information obtained during the exercise test could identify which of several factors contributed to the exercise limitation. Since the new method might be expected to reduce the difficulties experienced in assessing respiratory disability, its use is recommended.

Adult↗
PubMed1993

Mutations in the gene for the red/far-red light receptor phytochrome B alter cell elongation and physiological responses throughout Arabidopsis development.

Phytochromes are a family of plant photoreceptors that mediate physiological and developmental responses to changes in red and far-red light conditions. In Arabidopsis, there are genes for at least five phytochrome proteins. These photoreceptors control such responses as germination, stem elongation, flowering, gene expression, and chloroplast and leaf development. However, it is not known which red light responses are controlled by which phytochrome species, or whether the different phytochromes have overlapping functions. We report here that previously described hy3 mutants have mutations in the gene coding for phytochrome B (PhyB). These are the first mutations shown to lie in a plant photoreceptor gene. A number of tissues are abnormally elongated in the hy3(phyB) mutants, including hypocotyls, stems, petioles, and root hairs. In addition, the mutants flower earlier than the wild type, and they accumulate less chlorophyll. PhyB thus controls Arabidopsis development at numerous stages and in multiple tissues.

Amino Acid Sequence↗
PubMed1993

The role of plasma non-esterified fatty acids during exercise in type 2 diabetes mellitus.

Elevated fasting plasma non-esterified fatty acid (NEFA) levels have been reported in Type 2 diabetes. We examined whether such changes persist during low-grade exercise and influence carbohydrate metabolism. Eight Type 2 diabetic patients with moderate glycaemic control and eight healthy controls received the anti-lipolytic agent, acipimox, or placebo on separate occasions before exercising for 45 min at 35% pre-determined VO2max. Fasting plasma NEFA levels were similar (0.40 +/- 0.06 (SEM) and 0.45 +/- 0.05 mmol l-1; healthy and Type 2 diabetic subjects) following placebo, and increased to comparable levels with exercise (0.73 +/- 0.07 and 0.73 +/- 0.10 mmol l-1). Acipimox lowered basal NEFA levels (0.14 +/- 0.03 and 0.28 +/- 0.04 mmol l-1; both p < 0.05 vs placebo), and prevented the rise with exercise. Blood glucose (p < 0.001) and serum insulin (p < 0.01) levels were higher in the Type 2 diabetic patients (vs controls) for both treatments. Whole body lipid oxidation increased from baseline to a comparable degree with exercise following placebo (3.2 +/- 0.3 and 2.8 +/- 0.3 mg kg-1 min-1; healthy and Type 2 diabetic subjects, both p < 0.02). Although less marked, the same was also observed following acipimox (2.0 +/- 0.4 and 2.1 +/- 0.5 mg kg-1 min-1; both p < 0.05). Carbohydrate oxidation increased with exercise in both subject groups, but with no significant difference between the treatments. Thus, the metabolic response to low-grade exercise was normal in Type 2 diabetic patients with moderate glycaemic control, but occurred against a background of hyperinsulinaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1993

Contribution of hyperoxia to reduced pulmonary function after deep saturation dives.

Pulmonary function was measured before and after a 28-day saturation dive to a pressure of 0.25 MPa in eight subjects. PO2 was 40 kPa, with periods of 75 kPa for 2 h every 2nd day during the first 14 days, 50 kPa for the next 12 days, and a gradual fall to 21 kPa over the last 2 days in decompression. A 28-day saturation dive with six subjects to a pressure of 0.15 MPa and a PO2 of 21 kPa was used as control. The measurements included static and dynamic lung volumes and flows, transfer factor for carbon monoxide (TLCO), and a cycle ergometer exercise test. There was a significant reduction in TLCO of 9.8 +/- 6.0% (P < 0.001) after the dive when values were corrected for hemoglobin concentration changes. Effective alveolar volume was unchanged. There was a reduction in forced midexpiratory flow rate of 9.8 +/- 7.0% (P < 0.01), but forced vital capacity and forced expired volume in 1 s were unchanged. Peak oxygen uptake was reduced by 10.1 +/- 5.3% (P < 0.001). There were no significant changes in any of the lung function variables after the control dive. Exposure to raised PO2 contributes significantly to the changes in pulmonary function that have been reported after deep saturation dives to pressures of 3.1-4.6 MPa with a similar profile of oxygen exposure. TLCO is apparently a more sensitive index than vital capacity for oxygen toxicity.

Adult↗
PubMed1992

Clinical and pathologic findings of aphakic peripheral corneal edema: Brown-McLean syndrome.

Twenty-two patients (36 eyes) are reported with Brown-McLean syndrome, which consists of peripheral corneal edema associated with peripheral endothelial pigment deposits, usually after intracapsular cataract extraction. This group, the largest reported to date, had a spectrum of corneal alterations, those at the more severe end of the spectrum being both progressive and symptomatic. Some patients required medical and surgical treatment, including keratoplasty. Four corneas (two obtained surgically, two postmortem) were examined by light and electron microscopy (EM). Centrally, the corneas were relatively normal, but peripherally there were disintegrated endothelial cells with an abnormal posterior collagenous layer of Descemet's membrane. Scanning EM showed a somewhat distinct junction between the normal central endothelium and the diseased peripheral endothelium.

Adult↗
PubMed1992

Corneal epithelial basement membrane dystrophy: an overlooked cause of painless visual disturbances.

Although decreased vision from corneal epithelial basement membrane dystrophy (CEBMD) usually is associated with pain from corneal epithelial erosion, it may be an overlooked cause of painless, sometimes sudden, visual disturbance. We report a series of eight patients referred to our department with visual deficits for whom various diagnoses had been made. A total of 15 neurologic and ophthalmologic tests had been ordered before their referral. All patients had CEBMD as a cause for their visual deficit. Retroillumination through a dilated pupil and examination of the fluorescein tear film were the best methods to demonstrate the CEBMD. Six of the eight patients underwent epithelial debridement with complete resolution of their symptoms. We recommend that all patients with unexplained visual disturbances be examined closely for CEBMD.

Adult↗
PubMed1992

Racial differences in mortality from cardiovascular disease in Atlanta, 1979-1985.

Mortality from cardiovascular disease (CVD) for the period 1979 to 1985 in the Atlanta metropolitan population was reviewed for racial differences. About 28% of the population was black in 1980. Of 22,585 deaths from hypertension, stroke, ischemic heart disease, and atherosclerosis, 78.7% occurred among whites and 21.3% among blacks. Overall, ischemic heart disease accounted for 47.7% of these four types of CVD deaths for both races and sexes. Age-specific and age-adjusted rates were compared. Among these four causes of death, blacks have the greatest excess of deaths from hypertension over whites for both males and females; the excesses were more than 200% when the rates were age-adjusted. The excess risk of death from hypertension occurred for all ages in blacks, with an excess of about 10 times in 30- to 49-year-olds. An excess risk from stroke also occurred in blacks below the age of 75; the risk reversed afterward. The age-specific mortality rates revealed an excess from ischemic heart disease only between the ages of 30 and 59 years and from atherosclerosis between 40 and 59 years of age for black men. This age-related crossover in females did not occur until the age of 75 years for deaths attributed to these causes. These data suggest that blacks were at highest risk for all four causes at younger age groups.

Adult↗
PubMed1991

Role of plasma non-esterified fatty acids during and after exercise.

1. The importance of circulating non-esterified fatty acids as a substrate during and after low-grade exercise has been examined by using a nicotinic acid analogue to inhibit lipolysis. Seven healthy men received acipimox or placebo on separate occasions. After 90 min, bicycle exercise was performed for 45 min (40% of pre-determined maximum oxygen uptake), followed by a 60 min recovery period. 2. The plasma concentration of non-esterified fatty acids increased during exercise after placebo (320 +/- 80 to 630 +/- 110 mumol/l) and remained elevated in the post-exercise period. Basal concentrations were lower after acipimox (100 +/- 10 mumol/l; P less than 0.05); they declined to 60 +/- 10 mumol/l during exercise and remained at this level for the rest of the study. 3. Lipid oxidation increased from 0.8 +/- 0.1 to 4.2 +/- 0.5 mg min-1 kg-1 during exercise after placebo (P less than 0.001) and remained elevated in the post-exercise period (1.2 +/- 0.1 mg min-1 kg-1). It was lower after acipimox, but still increased from 0.3 +/- 0.1 to 2.3 +/- 0.2 mg min-1 kg-1 with exercise. Carbohydrate oxidation was increased after acipimox compared with after placebo, but only reached significance during the post-exercise period (P less than 0.05). 4. Although acipimox abolished the rise in the plasma concentration of non-esterified fatty acids during exercise, there was only a 50% decrease in the rate of lipid oxidation. This suggests that an alternative source of non-esterified fatty acids makes an important contribution to the supply of lipid for oxidation during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Acidic conditions permit effective nodulation of alfalfa by invasion-deficient Rhizobium meliloti exoD mutants.

Rhizobium meliloti exoD mutants are deficient in invasion of alfalfa nodules and, as a consequence, the nodules that exoD strains induce fail to fix nitrogen. These nodules appear to be arrested at the same stage as nodules induced by other exo mutants, which do not make an acidic exopolysaccharide called EPS I, or by ndv mutants, which do not produce a periplasmic cyclic beta(1,2) glucan. However previous genetic and biochemical evidence suggested that the nodule invasion defect of exoD mutants arose from a biochemical deficiency distinct from those of both EPS I-deficient exo mutants and ndv mutants. In this study, we characterize mutant phenotypes of exoD strains in both free-living and symbiotic states. Nodules induced by exoD mutants are generally small and empty of bacteria, and exhibit the same structural features as nodules induced by other invasion-deficient mutants. Putative incipient infection threads were visible in outer cortical cells of these nodules but not in the plant cells in the interior of the nodule. We show that exoD mutants are sensitive to alkaline conditions, ceasing to grow at elevated pH in liquid yeast extract cultures and exhibiting decreased viability in alkaline medium. Interestingly, we find that buffering the plant growth medium at slightly acidic pH (6.0-6.5) restores the ability of exoD mutants to invade alfalfa nodules. exoD mutants are thus alkali sensitive for both free-living and symbiotic phenotypes. This result implies that the nodule invasion defect of exoD mutants arises from their sensitivity to alkaline conditions and, furthermore, that alkaline conditions may obtain in the developing infection thread. The deduced amino acid sequence of ExoD is extremely hydrophobic, suggesting that the protein is membrane associated. We propose models whereby absence of a putative membrane protein might lead to sensitivity to alkaline conditions and consequent arrest of nodule invasion.

Amino Acid Sequence↗
PubMed1991

Rhizobium meliloti exoG and exoJ mutations affect the exoX-exoY system for modulation of exopolysaccharide production.

R. meliloti Rm1021 normally produces an acidic Calcofluor-binding exopolysaccharide, called succinoglycan or EPS I, which is required for successful nodulation of alfalfa by this strain. At least 13 loci affecting production of EPS I were previously mapped to a cluster on the second of two symbiotic megaplasmids in Rm1021, pRmeSU47b. A putative regulatory region was originally defined by the exoG and exoJ mutations. exoG and exoJ mutants produced less exopolysaccharide than wild-type strains and induced nitrogen-fixing nodules on alfalfa with reduced efficiency compared with the wild type. These mutants appeared to produce only a low-molecular-weight form of EPS I. Mutations called exoX cause an increase in exopolysaccharide production and map in the same region as the exoG and exoJ mutations. The DNA sequence of this region reveals that it contains two open reading frames, called exoX and exoY, which have homologs in other Rhizobium species. Interestingly, the exoG insertion mutations fall in an intergenic region and may affect the expression of exoX or exoY. The exoJ mutation falls in the 3' portion of the exoX open reading frame and is probably an allele of exoX that results in altered function. exoG and exoJ mutations limit EPS I production in the presence of exoR95 or exoS96 mutations, which cause overproduction of EPS I. Gene regulation studies suggest that ExoX and ExoY constitute a system that modulates exopolysaccharide synthesis at a posttranslational level. The deduced sequence of ExoY is homologous to a protein required for an early step in xanthan gum biosynthesis, further suggesting that the modulatory system may affect the exopolysaccharide biosynthetic apparatus.

Amino Acid Sequence↗
PubMed1991

The exoR gene of Rhizobium meliloti affects RNA levels of other exo genes but lacks homology to known transcriptional regulators.

Rhizobium meliloti strains mutant in the exoR gene overproduce an exopolysaccharide called succinoglycan or EPS I. Protein fusions to several different exo genes required for EPS I biosynthesis are expressed at a higher level in an exoR strain than in a wild-type strain, showing that the overproduction of EPS I in exoR strains results at least in part from increased gene expression. This regulation is important to nodulation, since exoR mutants fail to invade alfalfa nodules unless secondary suppressor mutations that cause a decrease in EPS I production occur. Here, we show that an exoR strain contains higher levels of mRNA for other exo genes than does the wild-type parental strain. ExoR therefore most probably exerts its regulatory effect at the level of transcription. In addition, we have localized, subcloned, and sequenced the exoR gene. A newly constructed insertion allele of exoR has the same phenotype as the original mutant. The deduced sequence of ExoR is 268 amino acids long but does not show homology to other sequenced genes.

Amino Acid Sequence↗
PubMed1991

The exoD gene of Rhizobium meliloti encodes a novel function needed for alfalfa nodule invasion.

During the symbiotic interaction between alfalfa and the nitrogen-fixing bacterium Rhizobium meliloti, the bacterium induces the formation of nodules on the plant roots and then invades these nodules. Among the bacterial genes required for nodule invasion are the exo genes, involved in production of an extracellular polysaccharide, and the ndv genes, needed for production of a periplasmic cyclic glucan. Mutations in the exoD gene result in altered exopolysaccharide production and in a nodule invasion defect. In this work we show that the stage of symbiotic arrest of exoD mutants is similar to that of other exo and ndv mutants. However, the effects of exoD mutations on exopolysaccharide production and growth on various media are different from the effects of other exo and ndv mutations. Finally, exoD mutations behave differently from other exo mutations in their ability to be suppressed or complemented extracellularly. The results suggest that exoD represents a new class of Rhizobium genes required for nodule invasion, distinct from the other exo genes and the ndv genes. We discuss models for the function of exoD.

Chromosomes, Bacterial↗
PubMed1991

Severe allergic keratoconjunctivitis and erythema multiforme after a routine eye examination: discerning the cause.

Acute allergic dermatitis of the eyelids with keratoconjunctivitis is associated with a specific triggering factor. Therapy for the acute inflammation can complicate the search for such a factor if the process worsens. We report a case of acute contact dermatitis and keratoconjunctivitis after a routine eye examination to demonstrate the difficulty in evaluating such patients and the role of skin patch testing in determining the cause.

1-Propanol↗