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Biomedical subjects

J Scott

Publications and source records attributed to J Scott.

At least 289 records · Page 16Linked to original sources
PubMed1994

Evaluation of chemical releases and worker exposures from filter press operations.

The exposures (inhalation and dermal) and releases (air, water, solids, and process streams) associated with the filtration of industrial wastewater sludge from an electronics manufacturing plant were characterized. Chemical releases and worker exposures for a target chemical (total copper) were measured over four operational cycles. Various aspects of the filtration operation believed to influence the measurement values were documented. Worker exposures associated with the discreet stages of the filter operation were measured. Ventilation patterns around the filter press were also monitored. The workers' time-weighted average exposures to total copper during the 113-minute operational cycle ranged from 3.1 to 25 micrograms/m3 (2.2 geometric standard deviation, 6.4 micrograms/m3 geometric mean concentration). The manual removal of filter cake comprised only 15% of the time in an average filtration cycle, but produced 72% of the workers' inhalation exposure. During this cake-removal stage, inhalation exposures ranged from 11 micrograms/m3 to 130 micrograms/m3 (2.5 geometric standard deviation, 30 micrograms/m3 geometric mean concentration). Differences in worker technique may account for the large range of inhalation exposures during the cake-removal stage. Exposures and releases were successfully determined for a single unit operation, as well as for the discreet stages of operation. The data generated will enable EPA to more accurately estimate worker exposures and chemical releases for new chemicals as required by the Toxic Substances Control Act. The approach utilized will benefit industrial hygienists in providing estimates of worker exposures and aid in the targeting of survey sampling.

Air Pollution↗
PubMed1994

The role of macronuclear DNA sequences in the permanent rescue of a non-mendelian mutation in Paramecium tetraurelia.

The paramecium tetraurelia mutant called d48 has a complete copy of the A surface protein gene in its micronuclei, but lacks the A gene in the macronucleus. Previous experiments have shown that microinjection of a plasmid containing the entire A gene or a large portion of the gene into the macronucleus of d48 rescued the cell line after formation of a new macronucleus (autogamy). Here we show that several different regions of the A gene can rescue d48, but 100% of the activity cannot be localized to a single, defined region. Inversion of a sequence contained within an A gene plasmid had no measurable effect on rescue efficiency and co-injection of two different plasmids results in enhancement of rescue activity despite the non-contiguous form of the DNA sequences. Both these results suggest that no specific product (RNA or protein) with defined end points is made from the rescuing fragment. A unique restriction site was created in the A gene and used to demonstrate that the injected DNA does not serve as a direct template for the synthesis of the new macronuclear DNA. Models to explain the action of the injected DNA are discussed.

Animals↗
PubMed1994

Change champions at the grassroots level: practice innovation using team process.

A nursing administrative group recognized the critical value of staff participation in the formulation of a restructuring project and guidance throughout the project. Using a team approach, a task force of three staff nurses, two assistant nurse managers, a nurse clinician, a nursing practice specialist, and a representative from nursing administration came together. They were given responsibility for researching and setting the course for restructuring change. A unit-based team including a unit secretary, a nursing attendant, licensed practical nurse (LPN), and six staff nurses was formed from volunteers from the 40-bed medicine unit to develop that unit's plan for restructuring. The unit-based team analyzed patient care needs and staff member roles. They created a new patient care technician role as well as a nurse care coordinator role. The role of the LPN was envisioned as providing technical support. Staffing mix was also determined by the unit-based team. Both the task force and the unit-based team continue to evaluate, troubleshoot, and take every opportunity to sell their vision to solidify it further as the foundation for the future of patient care services at the hospital. The process will soon move forward to a large surgical unit.

Communication↗
PubMed1994

The apolipoprotein B messenger RNA editing enzyme.

The editing of apolipoprotein (apo)B messenger RNA (mRNA) involves a novel C to U modification, which creates an in-frame stop-translation codon, thereby generating the carboxyl-terminal of apoB48. The 27 kDa catalytic subunit of the editing enzyme has been cloned and established to be a zinc-containing cytidine deaminase. The catalytic subunit is guided to the editing site by a second targeting subunit or subunits. A candidate for the targeting subunit is a 60 kDa protein that can be UV crosslinked to the sequence UGAU, which is part of a motif downstream of the editing site that is essential for editing.

Amino Acid Sequence↗
PubMed1994

Complex segregation analysis provides evidence for a major gene acting on serum triglyceride levels in 55 British families with familial combined hyperlipidemia.

Familial combined hyperlipidemia (FCHL) was first described as an autosomal dominant inherited trait with primary action on triglyceride levels and secondary effects on cholesterol metabolism. This conclusion has since been questioned by several groups despite subsequent supportive biochemical and metabolic studies. To reexplore the genetics of FCHL, we assembled 55 families from the United Kingdom comprising 559 persons ascertained through probands with both hypercholesterolemia and hypertriglyceridemia. The results of univariate complex segregation analysis were consistent with a major gene acting on triglyceride and explaining two thirds of the genetic variability and 20% of the phenotypic variance in triglyceride levels. Univariate analysis did not identify a major genetic component acting on cholesterol levels. Bivariate segregation analysis rejected a major gene model. We also reexamined the original FCHL pedigrees collected by Goldstein et al and obtained results similar to those in the UK families. The prospects for mapping putative major genes determining triglyceride levels in FCHL patients by linkage analysis are discussed.

Family Health↗
PubMed1994

Abnormal pressure natriuresis in the dog model of obesity-induced hypertension.

Obesity is considered to be a major factor in the pathogenesis of hypertension in industrialized countries. Recent studies have suggested that the kidneys may play an important role in the development of obesity-induced hypertension. The purpose of this study was to determine whether obesity-induced hypertension is associated with abnormalities in the pressure-natriuresis relation. Renal function studies were performed in anesthetized control dogs (body weight, 20.2 +/- 0.8 kg) and obese dogs (body weight, 26.4 +/- 0.7 kg) that were maintained on a high-fat diet for 5 to 6 weeks. Mean arterial pressure averaged 122 +/- 5 mm Hg in the control group (n = 6) and 148 +/- 7 mm Hg in the obese group (n = 8). The effects of renal perfusion pressure on renal hemodynamics as well as sodium and water excretions were examined at five levels of renal perfusion pressure ranging from 75 to 165 mm Hg. Pressure-natriuretic and diuretic responses were reduced in the obese dogs by 40% to 50%. The renal blood flow and glomerular filtration rate autoregulatory responses and fractional lithium excretion responses to changes in renal perfusion pressure were similar in the control and obese dog groups. Associated with the attenuated natriuretic response to renal perfusion pressure in the obese dogs were significant elevations in plasma renin activity (4.3 +/- 1.6 versus 1.6 +/- 0.5 ng angiotensin I/mL per hour), plasma aldosterone concentration (34.4 +/- 6.4 versus 15.3 +/- 3.2 ng/dL), and plasma insulin concentration (30.5 +/- 6.8 versus 20.9 +/- 2.9 IU/mL).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Functional characteristics of atrophic parotid acinar cells from rats after liquid feeding.

Rat parotid atrophy, induced by liquid feeding over 10 days, was manifested as gland weight loss (40%) and histologically as acinar shrinkage. Acinar secretory function was investigated in the same glands using enzymatically dispersed cell preparations and superfused gland slices. Results were normalized for the acinar proportional volume, determined by stereological analysis. Although total amylase activity was significantly lower in liquid-fed (LD) rats, the percentage amylase releases elicited by isoproterenol (10 mumol/L) and carbachol (10 mumol/L) were unchanged from controls (CON). Superfused gland slices from LD and control (CON) rats exhibited increases in membrane permeability (86Rb+ efflux) and in the efflux and re-uptake of K+ in response to acetylcholine (10 mumol/L). However, the recorded maxima were significantly lower in LD than in CON (86Rb+, 27% lower; K+ efflux, 35% lower; K+ re-uptake, 35% lower). Similarly, after 60-minute equilibration, the 36Cl- content of cells from LD rats was 57% lower than that from CON. Carbachol (10 mumol/L), acting for 1 min with bumetanide (100 mumol/L), elicited an efflux of 36Cl- from cells from LD rats, but this was significantly lower (32.2%) in LD than in CON (49.9%). The reduced levels of ion movement are probably commensurate with the reduced acinar cell volume occurring in LD rats. These results show that mechanisms for the formation of primary saliva (exocytosis and transepithelial ion movements) are substantially preserved in the altered acinar cells of LD rats. Thus, in salivary disorders, severe morphological acinar atrophy may not inevitably signify exhausted secretory function.

Amylases↗
PubMed1994

An evaluation of the treatment effectiveness of the Chicago Health Outreach Acupuncture Clinic.

Acupuncture is a treatment modality that is particularly applicable for homeless clients because of its low cost and portability as well as because of its effectiveness in treating the symptomatology of pain syndromes, substance abuse, and human immunodeficiency virus infection. A two-part descriptive study was conducted to determine the response to acupuncture of homeless persons at the Chicago Health Outreach Clinic. Part 1 of the study consisted of a retrospective chart review of 45 patients to assess acupuncture treatment effectiveness. Part 2 of the study consisted of using a numerical rating scale report form to assess treatment effectiveness of 30 patients. Part 1 of the study indicated that 51% had a positive response to treatment, 42% were indeterminate or lacked documentation of response, and 7% had no response to treatment. Part 2 of the study demonstrated that 97% had a positive response to treatment, with 3% reporting no response to treatment. Acupuncture treatment did effectively decrease the symptomatology of the homeless clients seen in the Chicago Health Outreach Acupuncture Clinic. Further research should involve follow-up of these clients to assess the length of symptom relief to further determine long-range effectiveness and cost of treatment.

Acupuncture Analgesia↗
PubMed1994

A. I. F. Scott & C. P. L. Freeman's "Edinburgh Primary Care Depression Study.

"OBJECTIVE--To compare the clinical efficacy, patient satisfaction, and cost of three specialist treatments for depressive illness with routine care by general practitioners in primary care. DESIGN--Prospective, randomised allocation to amitriptyline prescribed by a psychiatrist, cognitive behaviour therapy from a clinical psychologist, counselling and case work by a social worker, or routine care by a general practitioner. SUBJECTS AND SETTING--121 patients aged between 18 and 65 years suffering depressive illness (without psychotic features) meeting the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Third Edition for major depressive episode in 14 primary care practices in southern Edinburgh. MAIN OUTCOME MEASURES--Standard observer rating of depression at outset and after four and 16 weeks. Numbers of patients recovered at four and 16 weeks. Total length and cost of therapist contact. Structured evaluation of treatment by patients at 16 weeks. RESULTS--Marked improvement in depressive symptoms occurred in all treatment groups over 16 weeks. Any clinical advantage of specialist treatments over routine general practitioner care were small, but specialist treatment involved at least four times as much therapist contact and cost at least twice as much as routine general practitioner care. Psychological treatments, especially social work counselling, were most positively evaluated by patients. CONCLUSIONS--The additional costs associated with specialist treatments of new episodes of mild to moderate depressive illness presenting in primary care were not commensurate with their clinical superiority over routine general practitioner care. A proper cost-benefit analysis requires information about the ability of specialist treatment to prevent future episodes of depression.

Adolescent↗
PubMed1994

Cognitive therapy.

The scientific approach advocated in CBT has increased its credibility with more biologically orientated therapists (who have remained sceptical of other psychodynamic models), making the approach acceptable to a broad group of psychiatrists. There is a rich clinical literature describing the techniques and applications of CBT in a wide variety of settings. The acquisition of a selection of the above texts offers a useful starting point, and scanning of major British and American psychiatry and psychology journals is likely to turn up at least one important paper every few months. Those with a commitment to research would benefit from subscribing to the journal Cognitive Therapy and Research. CBT does not aim to be a panacea for every disorder, and cognitive therapists are critical of its overzealous use by inadequately trained or poorly informed therapists. To practise effectively, the therapist needs a coherent cognitive model of the problem being treated and, as such, must explore the theoretical background literature and critically evaluate the data from process and outcome research. Hopefully, this 'scientist-practitioner' approach, tracing the emergence and development of the theory and principles of the model underpinning the therapy, means that cognitive therapists practise what they preach.

Affective Symptoms↗
PubMed1994

Folate/vitamin B12 inter-relationships.

Folate deficiency causes anaemia owing to impaired purine and pyrimidine biosynthesis. Vitamin B12 deficiency causes an identical anaemia owing to metabolic trapping of intracellular folate. Vitamin B12 also causes nerve damage. Unlike the anaemia, the nerve damage is probably owing to inhibition of methyltransferase involved in nerve cell biosynthesis. This decreased activity is owing to a reduction in the availability of SAM, the methyl donor, together with product inhibition by its demethylated form, SAH.

Animals↗
PubMed1994

Pathological findings in clinically false-negative and false-positive neck dissections for oral carcinoma.

A series of 86 patients presenting with oral cancer underwent neck dissection (114 sides of neck), after preoperative staging by palpation under general anaesthesia and CT imaging. Detailed histopathological assessment of the surgical neck dissection specimens showed the incidence of clinically false-negative and false-positive assessments was 27% and 40%, respectively. Extranodal spread of metastatic carcinoma was present in 16% of clinically negative necks. The pathological findings provided plausible explanations for the clinical misdiagnosis in all 19 of the false-positive necks and in 13 of the 18 false-negative necks, where micrometastases or metastasis to nodes measuring less than 1.7 cm accounted for five and seven misdiagnosed cases, respectively. We conclude that the most stringent clinical protocols, even when supplemented by CT scanning, cannot be expected to achieve 100% accuracy. Detailed histopathological assessment provides the most reliable, currently available method of diagnosing cervical metastatic disease.

Adult↗