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J V Anderson

Publications and source records attributed to J V Anderson.

At least 19 recordsLinked to original sources
PubMed1995

Spinach leaf 70-kilodalton heat-shock cognate stabilizes bovine adrenal glucose-6-phosphate dehydrogenase in vitro without apparent stable binding.

Spinach (Spinacia oleracea L.) leaf tissue 70-kilodalton heat-shock cognate was purified by ATP-agarose affinity and gel filtration. Gel filtration of the affinity-purified protein resolved it into three forms: monomer, dimer, and oligomer. In the absence of ATP, the majority of the heat-shock cognate existed as a monomeric form with lesser amounts of dimer and oligomer. Addition of 3 mM ATP to the purified protein, containing all three forms, converted the dimeric and monomeric forms to a high-molecular-weight complex. Removal of ATP from the complex by dialysis resulted in the reappearance of the dimeric and monomeric forms. Addition of ATP to the highly purified monomer had no effect on its gel-filtration migration. Neither purified monomeric or dimeric forms showed stable binding to denatured proteins; however, both forms of the purified heat-shock cognate were able to stabilize the enzymatic activity of bovine adrenal glucose-6-phosphate dehydrogenase over a 48-h period at 25 degrees C. In addition, the activity of glucose-6-phosphate dehydrogenase in the presence of purified heat-shock cognate dimer or monomer could be rapidly decreased in an ATP-dependent fashion depending on the order of the substrate addition to the reaction mixture. Circular-dichroism studies indicated that addition of ATP to the spinach 70-kDa heat-shock cognate caused a conformation change from alpha-helical to a greater beta-sheet content. How conformational character may influence the stabilizing activity of the heat-shock cognate in a mechanism which does not require stable peptide binding is discussed.

Adenosine Triphosphate↗
PubMed1994

Structural organization of the spinach endoplasmic reticulum-luminal 70-kilodalton heat-shock cognate gene and expression of 70-kilodalton heat-shock genes during cold acclimation.

The 70-kD heat-shock proteins (HSP70s) are encoded by a multigene family in eukaryotes. In plants, the 70-kD heat-shock cognate (HSC70) proteins are located in organellar and cytosolic compartments of cells in most tissues. Previous work has indicated that HSC70 proteins of spinach (Spinacia oleracea) are actively synthesized during cold-acclimating conditions. We have isolated, sequenced, and characterized cDNA and genomic clones for the endoplasmic reticulum (ER) luminal HSC70 protein (immunoglobulin heavy chain-binding protein; BiP) of spinach. The spinach ER-luminal HSC70 is a constitutively expressed gene consisting of eight exons. Spinach BiP mRNA appears to be up-regulated during cold acclimation but is not expressed during water stress or heat shock. In contrast to the differential regulation of mRNA, the ER-luminal HSC70 protein levels remain constant in response to various environmental stresses. Two other members of the spinach 70-kD heat-shock (HS70) multigene family also show differential expression in response to a variety of environmental stresses. A constitutively expressed cytosolic HSC70 protein in spinach appears also to be up-regulated in response to both cold-acclimating and heat-shock treatments. Spinach also contains a cold-shock-induced HS70 gene that is not expressed during heat shock or water stress. Since HSP70s are considered to be involved with the chaperoning and folding of proteins, the data further support the concept that they may be important for maintaining cellular homeostasis and proper protein biogenesis during cold acclimation of spinach.

Acclimatization↗
PubMed1994

Differential influence of ATP on native spinach 70-kilodalton heat-shock cognates.

A constitutively expressed class of 70-kD heat-shock cognate (HSC70) proteins from spinach leaf tissue was purified based on their affinity for ATP-agarose. The affinity-purified spinach proteins were resolved into at least three different forms on two-dimensional gels. Under native conditions, and iN the absence of ATP, the affinity-purified proteins were separated into three molecular mass classes by gel-filtration chromatography; a monomer of 85 kD, a multimer of 280 kD, and a large molecular mass oligomer of > 650 kD. All molecular mass forms contained a major protein that migrated at 79 kD on sodium dodecyl sulfate-polyacrylamide gels. N-terminal sequencing of the 79-kD purified monomer showed the highest homology to the endoplasmic reticulum-luminal HSC70. Addition of Mg-ATP to monomeric HSC70 did not alter its migration during gel filtration. Addition of Mg-ATP to the dimer converted it to monomer and oligomeric forms, whereas the presence of ATP converted a fraction of the large molecular mass oligomeric form of HSC70 to dimeric and monomeric forms. Only the large molecular mass oligomeric HSC70 appears to autophosphorylate in vitro in the presence of [gamma-32P]-ATP. Dimers and monomers can bind ATP by a nonhydrolytic mechanism and undergo a conformational change in the presence of Mg-ATP. In this paper we discuss the effects that ATP may have on the regulation of plant HSC70.

Adenosine Triphosphate↗
PubMed1993

Antigen binding of a mouse monoclonal IgG1 is inactivated by heating but not by freeze/thaw cycling.

A mouse monoclonal antibody in ascitic fluid or in purified form was subjected to heating or repeated freeze/thaw cycles. Heating the antibody at 80 degrees C for 10 min completely destroyed its ability to bind to antigen. Unpurified antibody in ascitic fluid or purified antibody in buffer was frozen to -196 degrees C in liquid nitrogen and then thawed at room temperature. Purified antibody was also slowly frozen at -4 degrees C followed by thawing at room temperature. Regardless of the manner of freeze/thaw treatment or whether the antibody was purified or not, immunologic competence for its antigen was not lost. The results call into question the belief that freezing and thawing in all cases are necessarily deleterious to antibody structure and function.

Animals↗
PubMed1993

A work-site weight management program to reinforce behavior.

This pilot weight management project addresses the efficacy of reinforcing dietary behavior change versus weight loss. This 6-month program served professional and support staff participating in the work-site wellness program at a midwestern university. Behavior-contingent program data were compared with data from the previous model where contracts were made for weight loss. In the behavior-contingent program, dropout rate and satisfaction with the program compared favorably with the old model weight loss-contingent program. Contract adherence was 93% compared with 74% in the weight loss-contingent program. Actual pounds of weight lost were lower in the behavior-contingent program, however, long-term weight management must still be studied with this population.

Adult↗
PubMed1993

Malignant prolactinoma with extracranial metastases: a report of three cases.

OBJECTIVE: Prolactin-secreting tumours of the pituitary almost never metastasize extracranially. However, we have recently seen three such patients, whose presentation, clinical course and response to treatment are reviewed in order to determine whether they possess unique clinical features, and to assess optimum therapy. DESIGN AND PATIENTS: Three patients with extracranial metastases from prolactinomas have been retrospectively reviewed. MEASUREMENTS: Clinical courses, biochemical parameters and imaging modalities (CT, MR and radiolabelled somatostatin analogue scanning) and histopathology were assessed before and during different therapeutic regimens. RESULTS: All three patients' presentations were initially unremarkable, but later each had persistent and relentlessly increasing serum prolactin concentrations and evidence of distant spread of their tumours. The first patient presented aged 32 and was treated with repeated transsphenoidal resections of the tumour, pituitary radiotherapy, high dose bromocriptine therapy, the somatostatin analogue octreotide and chemotherapy. Nine years after the original diagnosis a liver biopsy revealed carcinoma cells positively immunostaining for prolactin. At autopsy further microscopically similar metastases were seen in both lungs and the left hilar lymph nodes. The second patient presented aged 48 and was treated with external beam pituitary radiotherapy, bromocriptine, transsphenoidal hypophysectomy and chemotherapy. Fifteen years after the original diagnosis bone biopsy revealed carcinoma cells positively immunostaining for prolactin; the patient developed interstitial nephritis and died in renal failure. The third patient presented aged 48 with hypogonadism and bitemporal hemianopia due to a macroadenoma. This was removed transfrontally and followed by external beam radiotherapy. After recurrence, further surgery and radiotherapy were undertaken, but the tumour continued to grow and the patient died suddenly of a pulmonary embolus. At autopsy, tumour was found in thoracic lymph nodes and lung capillaries. CONCLUSIONS: These three patients may be added to the previous two reported cases of malignant prolactinoma with extracranial spread. Several different therapies were tried but were of limited value in controlling the progression of the disease, although chemotherapy is an important modality to be considered. No particular factor or combination of factors at presentation differentiated these patients from more typical patients whose disease is much less aggressive.

Adult↗
PubMed1993

Effect of octreotide on gall stone prevalence and gall bladder motility in acromegaly.

Octreotide therapy in acromegaly is associated with an increased prevalence of gall stones, which may be the result of an inhibition of gall bladder motility. Gall stone prevalence in untreated acromegalic patients relative to the general population is unknown, however, and the presence of gall stones and gall bladder motility in these patients and in acromegalic patients receiving octreotide was therefore examined. Thirty four percent of 39 patients who had taken octreotide for a mean of 20 months had gall stones compared with 16% of 38 patients who had not been treated with octreotide (p < 0.005). In a subgroup of 21 patients studied prospectively over 4 to 18 months, two patients developed stones. No patient had symptoms referrable to their gall stones. In 31 untreated acromegalic patients, the mean fasting gall bladder volume was similar to that in normal subjects. Maximal percentage emptying, however, was impaired (34 v 64%, p < 0.001) and the mean postprandial residual gall bladder volume increased (21.7 v 9.0 ml, p < 0.001). Treatment with octreotide increased the mean postprandial residual volume further to 36.8 ml (p < 0.001). Gall bladder emptying in untreated acromegalic subjects is impaired. Octreotide further increases postprandial residual gall bladder volume and this may be a factor in the increased gall stone prevalence seen in these patients.

Acromegaly↗
PubMed1992

Plasma atrial natriuretic peptide and renin-aldosterone in patients with cirrhosis and ascites: basal levels, changes during daily activity and nocturnal diuresis.

Measurements of plasma atrial natriuretic peptide concentrations at 8 AM showed raised levels in 21 patients with cirrhosis and ascites (10.5 +/- 0.8 pmol/L) compared with levels in 10 age-matched controls (4.1 +/- 0.64 pmol/L; p less than 0.0001). In eight patients and 10 controls, atrial natriuretic peptide, plasma renin activity, plasma aldosterone and urinary sodium excretion were measured every 4 hr for 24 hr. Subjects were mobile between 8 AM and 11 PM and supine from 11 PM to 8 AM. In controls, urinary sodium excretion was highest between 4 PM and 11 PM (19.34 +/- 3.74 mumol/min) and lowest between midnight and 8 AM (7.06 +/- 1.23 mumol/min; p less than 0.001). In patients, urinary sodium excretion was 0.63 +/- 0.14 mumol/min between 4 PM and midnight and 1.85 +/- 0.71 mumol/min (p less than 0.08) between midnight and 8 AM. In patients during the day, mean plasma atrial natriuretic peptide concentration did not change despite large individual variation, but large, sustained rises in plasma renin activity and plasma aldosterone were seen. Correlations were noted between atrial natriuretic peptide and urinary sodium excretion between midnight and 8 AM (r = 0.65; p less than 0.02) and 4 PM and midnight (r = 0.54; p less than 0.05) but not between 8 AM and 4 PM. Plasma renin activity dropped from 12.54 +/- 2.49 at midnight to 7.41 +/- 0.88 pmol/hr/ml at 8 AM (p less than 0.05); plasma aldosterone decreased from 1,032 +/- 101 to 798 +/- 56 pmol/L (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1992

Prevalence of gastritis in patients with acromegaly: untreated and during treatment with octreotide.

OBJECTIVE: It has previously been suggested that acromegalic patients treated with the somatostatin analogue octreotide invariably have chronic gastritis. We have examined the prevalence of gastritis in a large group of acromegalic patients, untreated and during treatment with octreotide. DESIGN: We studied three groups of acromegalic patients: (A) untreated; (B) octreotide-treated; (C) a subgroup of these studied both before and during octreotide therapy. PATIENTS: Forty-eight patients, grouped as above, with active acromegaly were examined for the presence of gastritis. MEASUREMENTS: Gastroscopy and histological examination of gastric biopsies for the presence of gastritis and Helicobacter organisms were undertaken. The principal outcome was quantification of the prevalence of gastritis in the various study groups. RESULTS: Group A: 10 of the 33 patients (30%) had gastritis before any therapy with octreotide. Group B: 17 of 36 patients (47%) on octreotide treatment for 6-59 months (mean 20.5) had gastritis, and this was present in five out of the sub-group of eight patients (62%) treated for over 3 years. Group C: three of 21 patients (14%) developed gastritis during treatment with octreotide for between 6 and 23 months (mean 12.4). There was a highly significant association between the presence of gastritis and the presence of Helicobacter pylori organisms. CONCLUSIONS: Octreotide therapy of acromegaly may predispose to the development of gastritis, but this remains statistically unproven. Certainly, gastritis is not an invariable consequence of octreotide therapy, even after prolonged periods of treatment. The presence of gastritis is associated with H. pylori infection.

Acromegaly↗
PubMed1992

Possible mechanism and treatment of o,p'DDD-induced hypercholesterolaemia.

Ortho,para,dichlorodiphenyl dichloroethane (o,p'DDD, Mitotane (Roussell)) is used as an adrenolytic drug to reduce adrenocortical mass and circulating cortisol levels in Cushing's syndrome but has the unwanted side-effect of inducing hypercholesterolaemia. This paper examined the mechanism of that effect in 30 patients with Cushing's syndrome treated with o,p'DDD during the past 10 years. o,p'DDD increased serum cholesterol by 68 per cent, mainly by increasing LDL-cholesterol. The latter effect was not due to impaired binding of LDL to its receptor, as shown in vitro using cultured fibroblasts. Increases in plasma mevalonic acid during o,p'DDD administration were suggestive of increased cholesterol synthesis, this effect being reversed by simvastatin. These findings suggest that o,p'DDD causes hypercholesterolaemia by increasing cholesterol synthesis. It is proposed that this effect is due to the drug's known ability to block cytochrome P450-mediated reactions, thus impairing the formation of oxysterols responsible for down-regulating hepatic cholesterol synthesis. Treatment with simvastatin, an inhibitor of cholesterol synthesis, reverses the hyperlipidaemia and enables o,p'DDD therapy to be maintained without increasing cardiovascular risk.

Adult↗
PubMed1991

Human atrial natriuretic factor and renin-aldosterone in paracetamol induced fulminant hepatic failure.

It has been postulated that deficiency of a putative natriuretic factor, or resistance to such a factor, may contribute to sodium retention in fulminant hepatic failure. Levels of plasma human atrial natriuretic factor (h-ANF), plasma renin activity, and aldosterone concentration were measured in 33 patients with fulminant hepatic failure due to paracetamol overdose, and 12 healthy control subjects. Levels of h-ANF were raised only in patients with evidence of severe renal impairment (serum creatinine greater than 300 mumol/l and urine output less than 100 ml/24 hours). h-ANF values were median 4.15, range 2-9 pmol/l and 10.1, 1-25 pmol/l for the control and severe renal impairment groups respectively (p less than 0.001). In the latter plasma renin activity was raised compared to that in control subjects (median 19.8, range 1.04-41.7 and 2.86, 1.87-5.9 pmol/l/h respectively, p less than 0.02). Plasma aldosterone concentration was also raised in patients (2176, 199-6894 pmol/l compared to 368, 133-578 pmol/l in control subjects, p less than 0.01). Haemodialysis induced changes in circulating h-ANF which correlated with volume and right atrial pressure changes (p less than 0.001 and p less than 0.05 respectively). In six patients with no or mild renal failure infusion of 900 ml 5% human albumin solution caused a significant increase in plasma h-ANF (p less than 0.05) without natriuresis or diuresis, a finding compatible with the hypothesis that there may be resistance to h-ANF in this group. The present findings indicate that there is no deficiency of h-ANF in fulminant hepatic failure and that known mechanisms of h-ANF release are not impaired.

Acetaminophen↗
PubMed1991

Atrial natriuretic peptide in physiological doses does not inhibit the ACTH or cortisol response to corticotrophin-releasing hormone-41 in normal human subjects.

Whilst it has been postulated that atrial natriuretic peptide (ANP) may modulate pituitary hormone release, several investigations in non-human species have reported conflicting results when looking for an effect on the hypothalamo-pituitary-adrenal axis. However, in a recent study significant inhibition of corticotrophin-releasing hormone (CRH)-stimulated ACTH in cultured rat anterior pituitary cells occurred only with the complete peptide alpha-ANP(1-28). We have therefore investigated whether this form of ANP can inhibit CRH-stimulated ACTH and cortisol release in human subjects. Six healthy male volunteers received human alpha-ANP or placebo, and human CRH or placebo, on four separate occasions. ANP was infused at a rate of 0.01 micrograms/kg per min in order to achieve levels in the high physiological range. CRH was given as a bolus dose of 100 micrograms 30 min into the ANP infusion. Cortisol and ANP were measured by radioimmunoassay, the latter after extraction. ACTH was measured by immunoradiometric assay. The data were analysed by Student's paired t-test on basal, peak and incremental levels. Basal levels of ANP were within the normal range (2-5 pmol/l). With ANP infusion, mean +/- S.E.M. peak ANP levels were 29.6 +/- 3.1 pmol/l. There were no significant differences in mean basal cortisol and ACTH levels on each of the 4 study days. Mean peak cortisol and ACTH levels after CRH and ANP did not significantly differ from those achieved with CRH and placebo ANP. We thus conclude that at high physiological doses, circulating ANP does not inhibit CRH-stimulated ACTH or cortisol release.

Adrenocorticotropic Hormone↗
PubMed1990

Single, total paracentesis for tense ascites: sequential hemodynamic changes and right atrial size.

Hemodynamic changes induced by a single, total paracentesis were evaluated in 21 patients with tense ascites from whom 4 to 16 L of ascites were drained over 2 to 8 hr with no serious complications. At 60 min, compared to baseline, there was an increase in cardiac output (7.7 +/- 0.5 to 8.5 +/- 0.6 L/min, p less than 0.02) and a tendency for right atrial pressure to decrease (9.3 +/- 0.8 to 7.50 +/- 0.8 mm Hg, NS), with no change in pulmonary capillary wedge pressure (10.9 +/- 0.9 to 10.7 +/- 0.9 mm Hg). Between 3 and 12 hr later, there was a drop in right atrial pressure, pulmonary capillary wedge pressure and cardiac output to 5.6 +/- 0.6 (p less than 0.02), 7.2 +/- 0.8 mm Hg (p less than 0.002) and 7.2 +/- 0.6 L/min (NS) respectively, indicative of the development of relative hypovolemia and suggesting that therapeutic plasma expansion is appropriate at this time. Two-dimensional echocardiography before paracentesis (n = 8) showed a reduction in the right to left atrium area ratio as compared with values in patients with minimal ascites (0.54 +/- 0.04 vs 0.82 +/- 0.02, p less than 0.0001). This technique may help in identifying patients with right atrial compression caused by tense ascites.

Adult↗