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Biomedical subjects

S Robertson

Publications and source records attributed to S Robertson.

At least 109 records · Page 6Linked to original sources
PubMed1995

Practice visits: a pilot study.

OBJECTIVE: The aim of the paper is to report a pilot study of practice visits. METHOD: The study involved 35 psychiatrists as hosts and/or visitors, as well as four non-psychiatrist visitors, with the model and subsequent design changes described. RESULTS: The Quality Assurance Committee's rationale for practice visits is detailed, together with several focal concerns raised by committee members and other Fellows of the College. CONCLUSIONS: Feedback was highly positive, with visitors being generally more positive and enthusiastic than hosts. A follow-up questionnaire indicated ongoing enthusiasm for such an activity and provided evidence of participants making changes to their practices. Identified concerns and some suggested modifications to the pilot study design are noted.

Attitude of Health Personnel↗
PubMed1995

The lactational responses of dairy cows to amount of feed and to the source of carbohydrate energy.

An experiment was designed to test whether responses to variation in plane of nutrition conformed to a linear model or to a diminishing response curve model and to examine the influence of type of energy-yielding nutrient used in the ration on the response. Lactating Friesian cows (n = 18; mean, 126 DIM) were used in a Latin square experiment with three 4-wk periods. Diets consisted of hay and concentrates 40:60 (wt/wt, DM basis). The concentrates were based on grain, sugar beet pulp, or an equal mixture of the two. Each cow was offered low, medium, or high amounts of feed within the Latin squares, and feed type was compared between squares. The high amount was sufficient to maintain current body state and predicted final milk yield. Medium and low amounts were set to 1.5 and 3.0 kg of DM/d lower than the high amount, respectively. The source of dietary energy did not affect performance or response to amount of feed. The amount of feed had a highly significant linear effect on milk yield. The time taken for responses to a change in amount of feed to stabilize was 1 wk; milk yield did not reach a plateau but declined at a constant rate for the remaining 3 wk of the period. The rate of decline was significantly affected by amount of feed.

Animal Feed↗
PubMed1995

Primary carcinoid of the prostate in conjunction with multiple endocrine neoplasia IIb in a child.

Prostatic neoplasms are rare in childhood. We report a case of primary prostatic carcinoid in a 7-year-old boy who was subsequently diagnosed with multiple endocrine neoplasia IIb. To our knowledge this is the first report of either pediatric carcinoid of the prostate or of prostatic carcinoid in conjunction with neuronal intestinal dysplasia and medullary thyroid carcinoma suggestive of multiple endocrine neoplasia IIb. Management and histogenesis regarding this prostatic tumor are discussed as is a possible association with other neuroendocrine tumors.

Carcinoid Tumor↗
PubMed1994

Proliferative cell nuclear antigen in postradiotherapy prostate biopsies.

PURPOSE: To determine if staining for proliferative cell nuclear antigen (PCNA) can distinguish between biologically active and inactive "residual tumor" in postradiotherapy prostate biopsies by correlating PCNA staining with clinical outcome. METHODS AND MATERIALS: Since July 1990 all patients treated at the General Division of the Ottawa Regional Cancer Center with radical external beam radiotherapy for prostate cancer have had systematic transrectal ultrasound and transrectal ultrasound-guided biopsies beginning 12 months postradiotherapy. One hundred sixty-two patients have had 278 transrectal ultrasounds with four to seven biopsy specimens per examination. All biopsies were stained for prostate specific antigen and prostatic acid phosphatase. Keratin 903 was used to distinguish radiation atypia in benign glands from residual cancer. PCNA staining was done on all suspicious biopsies. Stage distribution was 31 T1b, 35 T2a, 61 T2b, and 35 T3-4. Median follow-up was 32 months (range 13-74). RESULTS: Negative biopsies have been obtained in 83% of T1b and T2a tumors and 70% of T2b and T3-4. Twenty-six tumors have recurred locally (T1b: 10%, T2a: 3%, T2b: 21%, T3-4: 26%), six with concurrent distant metastases. Of these 26 local failures, 23 had positive PCNA (mean 15.4 nuclei per 100) and three could not be determined (insufficient tissue). In 34 patients showing residual carcinoma at the first postradiotherapy biopsy, subsequent negative biopsies were obtained at a median of 25 months. Proliferative cell nuclear antigen staining could be performed in 23 of these 34 patients. Sixty-five percent (15/23) were negative on the first biopsy, indicating a nonproliferative state. In those with PCNA positive residual on initial biopsy, none retained PCNA staining on subsequent negative biopsies. One patient with an initial PCNA negative biopsy has failed locally. CONCLUSION: Proliferative cell nuclear antigen staining is useful in postradiotherapy prostate biopsies. Negative PCNA in a positive biopsy predicts (83-97%) for eventual resolution of tumor. Positive PCNA correlates with local failure (49-79%), but when present in an early biopsy (12-18 months), may still disappear.

Aged↗
PubMed1994

Infection and immunoregulation of T lymphocytes by parainfluenza virus type 3.

Human parainfluenza virus type 3 (HPIV3) is a major cause of disease in newborns and infants. It also has a striking potential to reinfect individuals throughout their lives, suggesting that HPIV3 does not induce lifelong immunity; however, the operative mechanism for the failure to prevent reinfection is not known. We have assessed the potential of the virus to infect nontransformed human T lymphocytes and have found that T cells are readily infected by the virus. Productive infection requires activation of the T cells and results in a marked inhibition of proliferation. Furthermore, our results indicate that exposure to the virus, even without overt expression of viral proteins as detected by immunohistology, profoundly alters the functional capacity of the T cells. The capacity of the virus to regulate T-lymphocyte function may play an important role in the failure of the virus to induce lifelong immunity.

Adult↗
PubMed1994

An 'instant gene bank' method for gene cloning by mutant complementation.

We describe a new method of gene cloning by complementation of mutant alleles which obviates the need for construction of a gene library in a plasmid vector in vitro and its amplification in Escherichia coli. The method involves simultaneous transformation of mutant strains of the fungus Aspergillus nidulans with (i) fragmented chromosomal DNA from a donor species and (ii) DNA of a plasmid without a selectable marker gene, but with a fungal origin of DNA replication ('helper plasmid'). Transformant colonies appear as the result of the joining of chromosomal DNA fragments carrying the wild-type copies of the mutant allele with the helper plasmid. Joining may occur either by ligation (if the helper plasmid is in linear form) or recombination (if it is cccDNA). This event occurs with high efficiency in vivo, and generates an autonomously replicating plasmid cointegrate. Transformants containing Penicillium chrysogenum genomic DNA complementing A. nidulans niaD, nirA and argB mutations have been obtained. While some of these cointegrates were evidently rearranged or consisted only of unaltered replicating plasmid, in other cases plasmids could be recovered into E. coli and were subsequently shown to contain the selected gene. The utility of this "instant gene bank" technique is demonstrated here by the molecular cloning of the P. canescens trpC gene.

Aspergillus nidulans↗
PubMed1994

Ferrous sulphate does not directly affect pteroylmonoglutamic acid absorption in rats.

A variety of compounds which bind to Fe have substantial reductions in absorption when co-administered with Fe compounds. The binding of both Fe2+ and Fe3+ ions to pteroylmonoglutamic acid and the pteroylmonoglutamate dianion was examined in vitro. In dimethylsulphoxide (DMSO) alone, pteroylmonoglutamate formed a 2:1 (pteroylmonoglutamate:Fe3+ ion) complex. However, in DMSO-aqueous Bis-Tris buffer (4:1, v/v; pH 6.0) no evidence of complex formation could be seen. Likewise spectroscopic evidence was obtained for complex formation with Fe2+ ion and pteroylmonoglutamate in DMSO alone but not in the aqueous DMSO buffer. In vivo studies examined the effect of FeSO4 on pteroylmonoglutamic acid absorption in an isolated perfused rat jejunal model of nutrient absorption. The dose of pteroylmonoglutamic acid approximated a human dose of 1 mg for the rat, while the FeSO4 doses were chosen to represent 6.4 mg, 64 mg and 300 mg human doses. There was no significant effect of FeSO4 on pteroylmonoglutamic acid absorption or instability of pteroylmonoglutamic acid in vivo in the presence of FeSO4 in the rat. Although 2:1 binding of pteroylmonoglutamic acid to Fe ions could be demonstrated in DMSO alone, no binding could be demonstrated in DMSO-Bis-Tris buffer (4:1, v/v; pH 6.0). It is unlikely that there will be a significant reduction in pteroylmonoglutamic acid absorption during concurrent ingestion of Fe preparations.

Animals↗
PubMed1994

Practice-based training in nurse management development: a case study.

One hundred and twenty nurse managers within the Central Sydney Area Health Service completed a program designed to concurrently strengthen professional skills and management systems. The program was based on functional review of work practices. It required consultation with the unit staff and collaboration with other sections of the organisation in designing and implementing quality improvement projects. The success of the program supports the idea that adult learners benefit from the opportunity to reflect on their experience at work. The program demonstrated that nurse managers will make major contributions to improvements in an organisation when the review process is legitimised, when they can participate in developing a framework for the review, and when organisational support is provided.

Education, Nursing, Continuing↗
PubMed1994

An atypical eating disorder with Crohn's disease in a fifteen-year-old male: a case study.

Most of the time, school or counseling psychologists are not specifically trained to work with children who have physical disorders that cause or exacerbate psychological problems. This article describes a 15-year-old male with delayed physical development who was referred for psychological evaluation and treatment of a suspected eating disorder. Six months after psychological intervention, appropriate eating behaviors were established, yet he had not gained weight as expected. After further medical evaluation, he was diagnosed as having Crohn's disease. Criteria for a DSM-III-R diagnosis of Anorexia Nervosa or Eating Disorder, Not Otherwise Specified, are discussed and symptoms of Crohn's disease described. Also discussed are differential diagnoses and practical recommendations for professionals in the field.

Adolescent↗
PubMed1993

Prenatal exposure to ethanol alters the postnatal development and transformation of radial glia to astrocytes in the cortex.

Postmitotic neurons migrate from a zone(s) near the ventricles to the neocortex. During this migration, neurons associate with radial glia. After serving their role as guides for neuronal migration, the radial glia transform into astrocytes. Prenatal exposure to ethanol causes abnormal neuronal migration. We examined the effects of gestational exposure to ethanol on radial glia and astrocytes. Radial glia were stained immunohistochemically with the antibody RAT-401, and astrocytes were labeled with an antibody directed against glial fibrillary acidic protein (GFAP). The subjects were the offspring of rats fed an ethanol-containing liquid diet (Et), pair-fed a liquid control diet (Ct), or fed chow and water (Ch). During the first postnatal week, radial glial fibers (in Et-treated rats and controls) stretched from the ventricular surface through the developing cerebral wall to the pial surface. In the Et-treated rats, the radial processes were less dense and more poorly fasciculated than they were in the Ch- and Ct-treated rats. Moreover, by postnatal day (P) 5, there was a significant reduction in RAT-401 immunostaining in the Et-treated rats, particularly in the superficial cortex. A similar reduction in control rats did not begin until P10. In all three treatment groups, GFAP-immunoreactive astrocytes were in the cortex throughout the period from P1 to P45. In neonates, GFAP-positive cells were distributed in the marginal zone (layer I) and the intermediate zone (the white matter). The number of GFAP-positive cells in the cortical plate increased steadily with time so that, by P26, GFAP-immunoreactive astrocytes were distributed evenly through all cortical laminae. Interestingly, between P5 and P12, the number of astrocytes was significantly greater in Et-treated rats than in controls. Thus prenatal exposure to ethanol induces the premature loss of RAT-401-positive processes and the precocious increase in GFAP immunostaining. These ethanol-induced changes in glial development indicate that ethanol accelerates the transformation of radial glia into astrocytes. Moreover, the ethanol-induced premature degradation of the network of radial glial fibers may underlie the migration of late-generated neurons to ectopic sites.

Animals↗
PubMed1993

Clinical relevance of trans-rectal ultrasound, biopsy, and serum prostate-specific antigen following external beam radiotherapy for carcinoma of the prostate.

PURPOSE: To correlate the results of routine transrectal ultrasound-guided prostate biopsies with the usual clinical parameters of digital rectal examination, prostate specific antigen and ultrasound in the follow-up of one hundred patients treated with radical radiotherapy for prostate cancer. METHODS AND MATERIALS: Stage distribution of the 100 patients was T1b; 19, T2a: 24, T2b: 36, T3: 20, T4: 1. Median follow-up is 26 months (range 15-48). One hundred forty-one ultrasound-guided biopsies have been performed with four to seven specimens at each examination. Initial biopsy was scheduled 12 months after radiotherapy and repeated every 6 months until negative or until there was clinical or biochemical evidence of recurrence. RESULTS: Negative biopsies were obtained at 12 months (range 9-15) in only 52%. Of 31 patients with a positive first biopsy who have had a second or third examination, 21 converted to negative at 16-29 months (median: 19) (stage T1b: 3, T2a: 6, T2b: 8, T3: 4). All 21 patients had maintained a normal or decreasing prostate specific antigen (PSA). At last review, negative biopsies had been obtained in 74% patients: 79% (15/19) of T1b, 71% (17/24) of T2a, 72%, (26/36) of T2b, and 76% (16/21) of T3/4. No patient with a negative biopsy has had a local recurrence. Transrectal ultrasound alone (sens: 49%, spec: 57%) was no better than rectal exam (sens: 73%, spec: 66%) in predicting a positive post radiotherapy biopsy. Metastatic disease developed in seven patients, 12% (3/26) of those with a positive biopsy and 5% (4/74) of those with a negative biopsy (p < 0.01). All seven presented first with a rising PSA. CONCLUSION: For patients with a positive biopsy 12 to 24 months after radiotherapy, PSA is the best indicator of biologically active tumor. This preliminary analysis indicates that there may be no need to treat patients with a positive biopsy and negative PSA in the absence of clinical recurrence.

Aged↗
PubMed1993

Rapid reversal of a motor nerve conduction deficit in streptozotocin-diabetic rats by the angiotensin converting enzyme inhibitor lisinopril.

The effect of treatment of rats with the angiotensin converting enzyme inhibitor lisinopril after 5 weeks of untreated streptozotocin-diabetes was examined by daily monitoring of sciatic motor conduction velocity to tibialis anterior muscle. Diabetes produced a 31.5% decrease in conduction velocity (P < 0.001). Lisinopril treatment caused a progressive improvement which was significant after 3 days (P = 0.002), full normalization being achieved by 6 days (P < 0.0001). After 7 days of treatment there followed a 7-day washout period in which no lisinopril was given. During this time conduction velocity declined to untreated diabetic levels over 3 days. A subsequent treatment period resulted in complete normalization of conduction velocity within 2 days (P < 0.0001). Thus, the marked functional effects seen for vasodilator treatment with lisinopril suggest that angiotension converting enzyme inhibitors may have potential therapeutic value in the treatment of diabetic neuropathy.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1993

Ferrous sulfate reduces cimetidine absorption.

A variety of drugs that bind to iron have significant reductions in absorption when coadministered with iron compounds. Cimetidine has a structure that would suggest strong binding to iron ions. In vitro experiments were performed to examine a variety of characteristics of the binding of iron to cimetidine. Further studies were conducted to determine the effect of concurrent administration of ferrous sulfate on cimetidine absorption in an in vivo isolated perfused rat jejunal model of drug absorption. The dose of cimetidine was chosen to represent a human dose of 300 mg, while the ferrous sulfate doses were chosen to represent 150- and 300-mg doses. The higher ferrous sulfate dose completely inhibited cimetidine absorption (P < 0.01), while the lower dose of ferrous sulfate caused a 63% reduction in cimetidine absorption (P < 0.05). In vitro iron in its ferrous from rapidly oxidizes to the ferric form. The ferric form of iron binds to cimetidine and may be the cause of the decreased cimetidine absorption. Care should be taken in prescribing iron supplements with cimetidine.

Animals↗
PubMed1993

The effects of evening primrose oil on nerve function and capillarization in streptozotocin-diabetic rats: modulation by the cyclo-oxygenase inhibitor flurbiprofen.

1. The aims of this study were first, to examine whether deficits in nerve conduction in streptozotocin-diabetic rats could be reversed by a 10% dietary supplement of evening primrose oil. Second, to determine the time-course of reversal, and third, to assess whether the effects could be blocked by the cyclo-oxygenase inhibitor flurbiprofen (5 mg kg-1 day-1). 2. One-month diabetes produced 20% and 15% deficits in sciatic motor and saphenous sensory conduction velocity respectively, which were maintained over 2 months diabetes. 3. The effect of 1-month evening primrose oil treatment on abnormalities caused by an initial month of untreated diabetes was examined. Motor and sensory nerve conduction velocity were restored to the non-diabetic level. 4. Resistance to hypoxic conduction failure was investigated for sciatic nerve trunk in vitro. The 80% conduction failure times were 29% and 55% prolonged by 1- and 2-month diabetes respectively. Evening primrose oil did not reverse the increased hypoxic resistance following 1-month untreated diabetes. 5. Sciatic nerve endoneurial capillary density was not significantly affected by diabetes, but was 16% increased in diabetic rats with reversal by evening primrose oil treatment for 1 month compared to 2-month untreated diabetes. 6. Serial motor conduction velocity measurement after 3-month untreated diabetes revealed complete normalization by evening primrose oil within 4 days. Cessation of treatment resulted in a rapid decline in conduction velocity over 24 h. 7. In a preventive study of 2-month duration, 6 groups of rats were used. These comprised non-diabetic controls, diabetic rats, and evening primrose oil-treated diabetic rats, both with and without flurbiprofen treatment. Flurbiprofen had no significant effect in non-diabetic rats, but produced an 11% worsening of motor conduction velocity and a 21% reduction of sciatic capillary density in diabetic rats. Evening primrose oil prevented the decreases in conduction velocity and increased hypoxic resistance with diabetes, and caused a 23% increase in capillary density. Flurbiprofen completely blocked the effect of evening primrose oil on conduction velocity, resistance to hypoxia, and capillarization.8. Six main conclusions were reached. First, evening primrose oil rapidly reverses conduction deficits in diabetic rats. Second, the effects of treatment may be very short-lived, suggesting a primary metabolic action. Third, evening primrose oil cannot reverse established changes in hypoxic resistance over 1-month treatment. Fourth, long-term treatment causes angiogenesis, suggesting a vascular action. Fifth,products of cyclo-oxygenase-mediated metabolism are necessary for maintaining vasa nervorum integrity in diabetic rats. Sixth, evening primrose oil probably acts by providing substrate for vasodilator prostanoid synthesis by vasa nervorum.

Action Potentials↗
PubMed1993

Polyol pathway-related skeletal muscle contractile and morphological abnormalities in diabetic rats.

This study examined the effect of inhibition of aldose reductase, the first enzyme in the polyol pathway, on fast and slow twitch skeletal muscle morphology and function in streptozotocin-induced diabetes in rats. There was a preventative investigation with diabetes duration of 4 months, and a reversal investigation where treatment was given for 2 months following an untreated period of 2 months. For slow twitch soleus muscle, contractions were prolonged by diabetes, and this was partially prevented but not reversed by treatment. Relaxation was profoundly slowed, and both prevention and reversal ameliorated the changes. Diabetes had minimal effects on tension production for soleus. However, for fast twitch extensor digitorum longus, although there was little effect on speed-related contractile parameters, tetanic tension production was progressively reduced with diabetes duration. This effect was antagonized by treatment. Soleus fatigue resistance was markedly reduced by diabetes, but restored to normal by treatment. There was a reduction in oxidative enzyme staining (succinic dehydrogenase), and capillary-fibre ratio, both of which were ameliorated by aldose reductase inhibition. Mean soleus fibre area was reduced after 4 months of diabetes, and this was prevented but not reversed by treatment. Fibre area was also reduced in extensor digitorum longus, particularly for fast glycolytic fibres. There was a small amelioration with treatment. It is concluded that enhanced polyol pathway activity makes a contribution to diabetic myopathy, and that aldose reductase inhibitors can prevent this by actions on muscle fibres and their vascular supply.

Aldehyde Reductase↗
PubMed1993

Nerve function in experimental diabetes in rats: effects of electrical stimulation.

The effects of unilateral electrical stimulation of the peroneal sciatic nerve branch were studied in streptozocin-diabetic rats of 12-wk duration. Stimulation was carried out over 7 days (10 Hz, 8 h/day) with chronically implanted electrodes. Compared with controls, there was a 25% conduction velocity (CV) deficit for the peroneal nerve supplying tibialis anterior muscle in the unstimulated leg, which was corrected by stimulation. For tibial fibers supplying soleus muscle, a similar diabetic CV deficit (20%) was normalized by stimulation, although soleus axons were not directly activated. In saphenous nerve, which has a functionally separate vascular supply, peroneal stimulation was ineffective. In anesthetized diabetic rats, stimulation caused an 18% reduction in tibialis anterior CV after 4 h. However, serial measurements showed progressive normalization of CV over 4 days of stimulation. On termination, CV returned to diabetic levels over 36-60 h. Sciatic nerve showed a 70% increase in resistance to hypoxic conduction failure with diabetes, which was halved by chronic stimulation. Acute experiments demonstrated that peroneal stimulation increased sciatic vascular conductance by 60%. We conclude that stimulation causes activity-related improvements in diabetic nerve blood flow and metabolism.

Animals↗
PubMed1993

Absence of an effect of ferrous sulfate on phenytoin absorption in the rat.

A variety of drugs which bind to iron have significant reductions in absorption when co-administered with iron compounds. The chemical structure of phenytoin indicates that there may be possible binding to iron ions. In vitro experiments were performed to determine whether any binding of iron to phenytoin occurred, and in vivo studies examined the effect of ferrous sulfate on phenytoin absorption in an isolated perfused rat jejunal model of drug absorption. The dose of phenytoin was limited by solubility and represents a human dose of 28 mg on a mg/kg basis for the rat assuming the total dose to be in 10 cm bowel in the rat. The ferrous sulfate doses were chosen to represent 28 and 300 mg doses on a similar basis to phenytoin. There was no significant effect of ferrous sulfate on phenytoin absorption or instability of phenytoin in the presence of ferrous sulfate in the rat. In vitro experiments indicated that little or no phenytoin binding to iron occurred. Results from animal model studies using low doses of phenytoin suggest it is unlikely that there will be a significant reduction in phenytoin absorption during concurrent therapy with iron salts.

Animals↗