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Biomedical subjects

J D Anderson

Publications and source records attributed to J D Anderson.

At least 109 records · Page 6Linked to original sources
PubMed1984

[Palliative radiation schedules with and without chemotherapy in advanced carcinoma of the esophagus].

In a prospective randomized study, 272 patients with advanced oesophageal cancer were treated with radiation and bleomycin or vinblastine or a combination of both cytostatics. Two radiation schedules were tested, the one involving larger fractions in a shorter period of time. Evaluation of the treatment results showed that 67% of patients experienced significant relief of dysphagia. The median survival was 3 months and the 1-year survival 7%. No statistical difference in survival was noted among the different chemotherapy or radiation groups (level of significance 5%). It was concluded that monochemotherapy as given in this study made no difference in the treatment result. The larger radiation fraction and shorter treatment time schedule was as effective as the more conventional schedule and is the preferred treatment because of the shorter hospitalization period. A pharyngostomy tube proved effective in feeding the patients. Oesophageal cancer is a systemic disease and polychemotherapy will have to play a prominent part in a multimodality treatment approach if results are to improve.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1984

[Increased incidence of skull metastases in neuroblastoma].

Children with neuroblastoma sometimes present with skull and peri-orbital metastases. Recent radionuclide studies confirm the increased incidence of skull metastases compared with adult metastatic carcinoma. Malignant tumours generate skeletal metastases by spread to the bone marrow. The relatively large head of a young child results in a relatively larger proportion of bone marrow in the skull, which explains the increased incidence of skull metastases in children with metastatic skeletal neuroblastoma.

Child, Preschool↗
PubMed1984

Correlation of hemodynamically significant internal carotid stenosis with pulsed Doppler frequency analysis.

Systolic and mean pressure gradients across internal carotid stenoses were measured at the time of carotid endarterectomy in the arteries of 90 patients, all of whom underwent angiography. Eighty-two of these patients also had pulsed Doppler ultrasonic arteriography with real-time spectrum analysis. There were 71 (79%) high grade stenoses of greater than 50% diameter reduction by angiography. Significant systolic pressure gradients (greater than or equal to 10 mmHg) were identified in 41 patients (46%), 38 (46%) of whom underwent ultrasonic evaluation. A pulsed Doppler frequency measured within the stenosis equal to or greater than 6.5 kiloHertz had a sensitivity of 94.7% (36/38) in identifying pressure reducing lesions with a specificity of 47.7% (21/44). Positive predictive value was 61% (36/59). Angiographic criteria (50% diameter reduction) exhibited a sensitivity of 97.6% (40/41), a specificity of 36.7% (18/49) and a positive predictive value of 56.3% (40/71). Negative predictive value was 94.7% for angiography and 91.3% for ultrasonic arteriography. A pulsed Doppler frequency equal to or greater than 6.5 kiloHertz appears to accurately identify lesions that are at risk to reduce distal internal carotid pressure under operative conditions with a sensitivity similar to angiography. This criterion has a positive predictive value and specificity that is slightly superior to angiography and a high negative predictive value. Pulsed Doppler spectrum analysis provides physiologic information relative to blood flow velocity that is complimentary to the anatomic data provided by angiography for assessing the potential for hemodynamic significance of internal carotid stenoses.

Blood Pressure↗
PubMed1984

Enhancement by ethylene of cellulysin-induced ethylene production by tobacco leaf discs.

Cellulysin-induced ethylene production in tobacco (Nicotiana tabacum L.) leaf discs was enhanced several-fold by prior exposure of the leaf tissue to ethylene. This enhancement in the response of the tissue to Cellulysin increased rapidly during 4 and 8 hours of pretreatment with ethylene and resulted from greater conversion of methionine to ethylene. On treatment with Cellulysin, the content of 1-aminocyclopropane-1-carboxylic acid (ACC) in leaf discs not pretreated with ethylene markedly increased while that of the ethylene-pretreated tissue was only slightly higher than in the tissue incubated in the absence of Cellulysin. Ethylene-treated tissue, however, converted ACC to ethylene at a faster rate than air controls. These data indicate that ethylene stimulates Cellulysin-induced ethylene production by stimulating the conversion of ACC to ethylene. Data are also presented on a possible relation of this phenomenon to ethylene produced by the tobacco leaf upon interaction with its pathogen, Alternaria alternata.

Journal Article↗
PubMed1984

Rhythmicity in ethylene production in cotton seedlings.

Cotyledons of cotton (Gossypium hirsutum L.) seedlings grown under a photoperiod of 12 hour darkness and 12 hour light showed daily oscillations in ethylene evolution. The rate of ethylene evolution began to increase toward the end of the dark period and reached a maximum rate during the first third of the light period, then it declined and remained low until shortly before the end of the dark period. The oscillations in ethylene evolution occurred in young, mature, and old cotyledons (7 to 21 day old). These oscillations in ethylene evolution seemed to be endogenously controlled since they continued even when the photoperiod was inverted. Moreover, in continuous light the oscillations in ethylene evolution persisted, but with shorter intervals between the maximal points of ethylene evolution. In continuous darkness the oscillations in ethylene evolution disappeared. The conversion of [3,4-(14)C]methionine into [(14)C] ethylene followed the oscillations in ethylene evolution in the regular as well as the inverted photoperiod. On the other hand, the conversion of applied 1-aminocyclopropane-1-carboxylic acid into ethylene did not follow the oscillations in ethylene evolution, but was affected directly by the light conditions. Always, light decreased and darkness increased the conversion of applied 1-aminocyclopropane-1-carboxylic acid into ethylene. It is concluded that in the biosynthetic pathway of ethylene the conversion of 1-aminocyclopropane-1-carboxylic acid into ethylene is directly affected by light while an earlier step is controlled by an endogenous rhythm.

Journal Article↗
PubMed1984

Rhythmical changes in the sensitivity of cotton seedlings to herbicides.

Cotton (Gossypium hirsutum L.) seedlings that were grown under a photoperiod of 12 hours darkness and 12 hours light showed oscillations in their sensitivity to the herbicides sodium 5-(2-chloro-4-trifluoromethyl)-phenoxy)-2-nitrobenzoate (acifluorfen), butyl 2-(4-((5-(trifluoromethyl)-2-pyridinyl)oxy)phenoxy)propanoate (fluazifop) and 3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (bentazon). Sensitivity was expressed in appearance of necrotic areas on the cotyledons and in decreased growth of the shoot. The seedlings were least sensitive in the beginning and middle of the light period, then the sensitivity increased and reached its maximum during the beginning and middle of the dark period and then declined. Seedlings grown from germination under continuous light exhibited very small or no oscillations in sensitivity. The oscillations in sensitivity were entrained by one cycle of darkness and light. A cycle of 12 hours darkness and 12 hours light triggered the greatest oscillations while either increasing or decreasing the duration of the dark period resulted in smaller oscillations. Apparently, these oscillations in sensitivity to herbicides were endogenously controlled since after entrainment they continued irrespective of the light conditions.

Journal Article↗
PubMed1983

Study of the enhancement of beta-lactam activity by amdinocillin in a model of the human urinary bladder.

Synergy between a 2:1 combination of ampicillin and amdinocillin was studied with 10 urinary isolates of Enterobacteriaceae. Synergy was observed with six organisms in a bladder model that reproduced many features of the milieu of the human bladder. Antibiotic susceptibility of these organisms was also determined by the agar incorporation plate method, by tube dilution (urine and broth), microtiter method (urine and broth) and disk susceptibility test. Minimal inhibitory concentrations of individual antibiotics were of no value in predicting the synergistic response and were sometimes misleading. None of the laboratory tests could predict synergy in the bladder model. Evidence is available that the bladder model may be superior to other in vitro tests for synergy studies.

Amdinocillin↗
PubMed1983

The effect of treatment of the associated disease on the development of amyloidosis in the experimental animal.

Thirty-five golden hamsters infected with Leishmania donovani were treated with Pentostam and followed up to determine the effect of treatment on the development of secondary amyloidosis. Seventy untreated golden hamsters infected with L. donovani were followed up as controls to determine the pattern of development of secondary amyloidosis. Amyloid developed in all animals treated and untreated. The treatment significantly prolonged the survival time, but did not inhibit the development of renal amyloid in animals shown by biopsy to be free from renal amyloid at the time of treatment. When amyloid was present in kidney at the time of treatment it progressed invariably to renal failure.

Amyloidosis↗
PubMed1983

Effect of bile salt perfusion and intraduct pressure on ionic flux and mucosal ultrastructure in the pancreatic duct of the cat.

Net ionic flux and mucosal ultrastructure were examined following perfusion of the cat pancreatic duct with bicarbonate or sodium taurocholate solutions (5-40 mM). Taurocholate perfusion increased net Cl- gain, net HCO3- loss and net K+ gain and was associated with significant widening of lateral intercellular spaces and increased complexity of intercellular labyrinths. Increased perfusion pressure (30 mm Hg) did not affect flux or ultrastructure during perfusion with bicarbonate but increased net ion flux significantly during perfusion with 40 mM sodium taurocholate. Ultrastructural changes during perfusion of 40 mM taurocholate at increased pressure were not consistent but focal epithelial disruption and cell shedding were seen occasionally. The hypothesis is advanced that taurocholate perfusion triggers physiological transport mechanisms and may make the duct mucosa more vulnerable to other potentially harmful agents. The significance of these changes in the pathogenesis of acute pancreatitis in man remains uncertain and care must be exercised before extrapolating from observed net ion flux data in this animal model.

Animals↗
PubMed1982

Biosynthesis of ethylene from methionine in aminoethoxyvinylglycine-resistant avocado tissue.

This study was conducted to determine if aminoethoxyvinylglycine (AVG) insensitivity in avocado (Persea americana Mill., Lula, Haas, and Bacon) tissue was due to an alternate pathway of ethylene biosynthesis from methionine. AVG, at 0.1 millimolar, had little or no inhibitory effect on either total ethylene production or [(14)C] ethylene production from [(14)C]methionine in avocado tissue at various stages of ripening. However, aminoxyacetic acid (AOA), which inhibits 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (the AVG-sensitive enzyme of ethylene biosynthesis), inhibited ethylene production in avocado tissue. Total ethylene production was stimulated, and [(14)C]ethylene production from [(14)C]methionine was lowered by treating avocado tissue with 1 millimolar ACC. An inhibitor of methionine adenosyltransferase (EC 2.5.1.6), l-2-amino-4-hexynoic acid (AHA), at 1.5 millimolar, effectively inhibited [(14)C]ethylene production from [(14)C]methionine in avocado tissue but had no effect on total ethylene production during a 2-hour incubation. Rates of [(14)C]AVG uptake by avocado and apple (Malus domestica Borkh., Golden Delicious) tissues were similar, and [(14)C]AVG was the only radioactive compound in alcohol-soluble fractions of the tissues. Hence, AVG-insensitivity in avocado tissue does not appear to be due to lack of uptake or to metabolism of AVG by avocado tissue. ACC synthase activity in extracts of avocado tissue was strongly inhibited (about 60%) by 10 micromolar AVG. Insensitivity of ethylene production in avocado tissue to AVG may be due to inaccessibility of ACC synthase to AVG. AVG-resistance in the avocado system is, therefore, different from that of early climacteric apple tissue, in which AVG-insensitivity of total ethylene production appears to be due to a high level of endogenous ACC relative to its rate of conversion to ethylene. However, the sensitivity of the avocado system to AOA and AHA, dilution of labeled ethylene production by ACC, and stimulation of total ethylene production by ACC provide evidence for the methionine --> SAM --> ACC --> ethylene pathway in avocado and do not suggest the operation of an alternate pathway.

Journal Article↗
PubMed1981

Urinary tract infections due to Staphylococcus saprophyticus biotype 3.

Staphylococcus saprophyticus biotype 3 (Micrococcus subgroup 3 or M3) has usually been shown to be the second commonset cause of urinary tract infections in European women who are not in hospital. It generally causes pyuria and symptoms as severe as those caused by Escherichia coli. Unlike S. epidermidis it is seldom found as a contaminant in midstream urine specimens, and almost exclusively infects women in their reproductive years. However, S. saprophyticus is seldom differentiated from S. epidermidis in Canadian clinical laboratories. Urinary isolates of S. saprophyticus were presumptively differentiated from other coagulase-negative Micrococcaceae by their resistance to novobiocin as demonstrated by a simple disc susceptibility test that misidentified the infecting organism in only 3.4% of specimens. These novobiocin-resistant, coagulase-negative organisms caused similar proportions of the urinary tract infections in young women in York, England and Vancouver -- 6.6% and 6.9% respectively. In York these organisms were associated with significantly greater pyuria than novobiocin-sensitive organisms or bile-tolerant streptococci but not S. aureus or Enterobacteriaceae. In both communities novobiocin-sensitive, coagulase-negative Micrococcaceae were appreciably more resistant to penicillin than novobiocin-resistant organisms. Thus, differentiating S. saprophyticus from novobiocin-sensitive, coagulase-negative organisms provides information that is clinically useful, particularly for primary care practitioners working in the community or in outpatient clinics.

Adult↗
PubMed1981

Some Characteristics of the System Converting 1-Aminocyclopropane-1-carboxylic Acid to Ethylene.

The rate of C(2)H(4) production in plant tissue appears to be limited by the level of endogenous 1-aminocyclopropane-1-carboxylic acid (ACC). Exogenous ACC stimulated C(2)H(4) production considerably in plant tissues, but this required 10 to 100 times the endogenous concentrations of ACC before significant increases in C(2)H(4) production were observed. This was partially due to poor penetration of ACC into the tissues. Conversion of ACC to C(2)H(4) was inhibited by free radical scavengers, reducing agents, and copper chelators, but not by inhibitors of pyridoxal phosphate-mediated reactions. The system for converting ACC to C(2)H(4) may be membrane-associated, for it did not survive treatment with surface-active agents and cold or osmotic shock reduced the capacity of the system to convert ACC to C(2)H(4). The reaction rate was sensitive to temperatures above 29 and below 12 C, which suggests that the system may be associated with membrane-bound lipoproteins. The data presented support the possibility that the conversion of exogenous ACC to C(2)H(4) proceeds via the natural physiological pathway.

Journal Article↗
PubMed1981

Polyamines inhibit biosynthesis of ethylene in higher plant tissue and fruit protoplasts.

Ethylene production in apple fruit and protoplasts and in leaf tissue was inhibited by spermidine or spermine. These polyamines, as well as putrescine, inhibited auxin-induced ethylene production and the conversion of methionine and 1-aminocyclopropane-1-carboxylic acid to ethylene. Polyamines were more effective as inhibitors of ethylene synthesis at the early, rather than at the late, stages of fruit ripening. Ca(2+) in the incubation medium reduced the inhibitory effect caused by the amines. A possible mode of action by which polyamines inhibit ethylene production is discussed.

Journal Article↗