Biomedical subjects

B G Miller

Publications and source records attributed to B G Miller.

At least 55 records · Page 3Linked to original sources

PubMed1996

Analytical criteria for predicting apparent digestibility of soybean protein in preruminant calves.

A series of experiments on the use of soybean as a protein source in milk replacers for veal calves was undertaken to determine the relationships between the physicochemical and antinutritional properties and apparent digestibilities of nine soybean products. Soybean provided between 58 and 71% of dietary CP, and skim milk or whey powder provided the remainder. Soybean products were analyzed for CP, native protein, aggregated protein, carbohydrate-linked protein, peptides, antitryptic activity, and immunoreactivity of lectin, glycinin, alpha-conglycinin, and beta-conglycinin. The apparent digestibility of N calculated for soybean protein varied between 59 and 84%. Simple linear correlations were significant between apparent digestibility of soybean N and concentrations of native protein, antitryptic activity, glycinin, alpha-conglycinin, and beta-conglycinin. However, only variation in antitryptic activity, alpha-conglycinin, and beta-conglycinin contributed significantly to an explanation for the variation in apparent digestibility of soybean N in a multiple linear equation. Under our experimental conditions, beta-conglycinin was the best predictor of digestibility of soybean N. Antitryptic activity became the best predictor when soybean products had no detectable beta-conglycinin.

Animal Nutritional Physiological Phenomena↗

PubMed1996

Plasma prolactin in schizophrenia subjects treated with Seroquel (ICI 204,636).

Treatment with standard antipsychotic medications causes side effects such as hyperprolactinemia and extrapyramidal symptoms. Because these side effects can cause noncompliance with antipsychotic medication and consequent relapse, they add to the morbidity of schizophrenia. A compound with antipsychotic efficacy but without the side effects of standard antipsychotic agents would improve compliance and treatment outcomes and enhance quality of life. Improved compliance, reduced relapse, and decreased hospitalization would also reduce the cost of treatment of schizophrenia. Seroquel (ICI 204,636), an atypical antipsychotic compound in Phase III development, was found to be well tolerated and effective in treating subjects with DSM-III-R schizophrenia in three Phase II clinical trials. Analysis of plasma prolactin concentrations obtained during these trials revealed that ICI 204,636 did not differ from placebo in its effect on plasma prolactin after up to 6 weeks of treatment; no significant difference was found in the degree of decline of plasma prolactin levels when subjects treated with ICI 204,636 and placebo were compared. A significant difference was found, however, between ICI 204,636- and chlorpromazine-treated subjects; prolactin levels in ICI 204,636-treated subjects fell to a greater degree than they did in chlorpromazine-treated subjects, however in all three trials, ICI 204,636 did not cause sustained elevation of prolactin.

Adult↗

PubMed1995

Bromo-deoxyuridine (BRDU) uptake in the lungs of rats inhaling amosite asbestos or vitreous fibres at equal airborne fibre concentrations.

Rats were exposed, by inhalation, to target airborne fibre concentrations of 1000 f/ml (PCOM fibres by WHO criteria) of a long amosite asbestos sample and a vitreous fibre sample; the target was closely attained for both fibre samples. The size distributions of the two fibre samples was closely similar. Rats were placed in the chambers for 7 hours and then, following a further 16 hours in room air, were injected with bromo-deoxyuridine (BRDU). The presence of BRDU-positive cells in terminal bronchioles/alveolar ducts was assessed in blocks taken from various parts of the left lung, from apex to base. There were significant differences in the proliferative responses between animals but there were also significant differences between the treatments. Lungs from rats exposed to vitreous fibres showed no greater response than the controls, but there was a markedly greater proliferative response in the lungs of rats inhaling long amosite. There was a decreasing gradient of proliferative response from the apex of the lung to the base with all treatments. This could be explained by different degrees of deposition in different areas of the lung. Similar amounts of fibre accumulated in the lungs of rats exposed to the two fibre types and it is unlikely that dissolution could be important over the timescale used here. We conclude that, when amosite asbestos deposits in the lungs of rats it stimulates a proliferative response and that deposition of an equal number of similar-sized vitreous fibres has no effect.

Air Pollutants↗

PubMed1995

The dilemma of mental health paraprofessionals at home.

The use of community member paraprofessionals in the delivery of mental health services is complicated by the changing nature of the paraprofessional's social relationships within the community. We use an anthropological model of Coast Salish social organization and data from a current delivery system, the Swinomish (Washington) Tribal Mental Health Project, to suggest ways to conceptualize and account for such complications.

Adult↗

PubMed1994

The effect of delayed weaning on the development of oral tolerance to soya-bean protein in pigs.

The antibody response to a dietary antigen (soya-bean protein) and the development of oral tolerance was studied in pigs in a family pen system where the piglets are left with their mothers and gradually wean themselves onto a soya-bean-based diet over a 12 week period. In the first experiment three groups of pigs (eight pigs/group) aged either 2, 8 or 13 weeks were immunized with soya-bean protein or ovalbumin (OvA; controls) intra-peritoneally (i.p.) in Quill A adjuvant and subsequently boosted 2 weeks later. All groups showed an IgG response to the injected antigens indicating lack of tolerance induction to the dietary antigen. Interestingly the groups injected with OvA showed an almost identical response to soya-bean protein as the groups injected with soya-bean protein. In a second experiment with a similar protocol, soya bean was withdrawn from the feed before immunization which resulted in lack of response to soya-bean protein in the groups injected with OvA and a lack of response to injected soya-bean protein in the 14-week-old group, indicating that systemic tolerance was established by 12 weeks of age. The results from the two experiments suggest a compartmentalized response to soya-bean protein i.e. local antibody production to dietary soya bean along with systemic tolerance to injected soya-bean protein. The work also suggests that delayed 'natural' weaning may avoid damaging hypersensitivity reactions associated with early weaning.

Aging↗

PubMed1994

Development of the Regular Interlaboratory Counting Exchanges (RICE) scheme to include visual reference counts and samples from asbestos clearance operations.

The RICE proficiency testing scheme for asbestos fibre counting operated until 1992 with industrial samples and with reference counts produced by an image analyser (Magiscan). The visual counts produced in RICE by the participating laboratories have now been used to develop a reliable reference count for these industrial samples. Concurrently with the routine participation in RICE, laboratories also counted samples from asbestos clearance operations; these counts were used to develop suitable reference counts and performance limits for this type of sample. The width of this satisfactory performance interval is proportional to the natural variation in the data on the samples and is therefore a fixed interval on the log scale (of sample density) for high density samples and a fixed interval on the square-root scale for low density samples (where counting normally stops after a fixed number of fields). These developments led to the introduction of visual reference counts and clearance samples into RICE during 1992.

Air↗

PubMed1994

Development of large intestinal attaching and effacing lesions in pigs in association with the feeding of a particular diet.

Hysterotomy-derived piglets were kept in gnotobiotic isolators and artificially colonized at 7 days of age with an adult bovine enteric microflora. At 3 weeks of age, the pigs were transferred to conventional experimental accommodation and weaned, either onto a solid diet that had been associated with field cases of typhlocolitis in pigs or onto a solid control diet. At necropsy at 5 weeks of age, groups of pigs fed the diet associated with field cases of typhlocolitis were found to have developed typhlocolitis. This was absent from the groups fed the control diet. The typhlocolitis was characterized by attaching and effacing lesions typical of those described following experimental inoculation of various species with enteropathogenic Escherichia coli. A nonverocytotoxic, eae probe-positive E. coli serotype O116 was isolated from pigs on the colitis-associated diet but not from any of the pigs on the control diet. Coliform bacteria attached to the colonic lesions reacted with polyclonal antiserum to E. coli O116 in an immunoperoxidase assay of histological sections of affected tissue. No reaction with this antiserum was observed in corresponding tissue sections taken from pigs on the control diet. No colon lesions were observed in germfree pigs fed either of the diets. It is postulated that proliferation and possibly expression of pathogenicity of the attaching and effacing E. coli responsible for the lesions are strongly influenced by diet.

Animal Feed↗

PubMed1994

Altered immune response to proteins fed after neonatal exposure of piglets to the antigen.

The weaning of piglets onto soya proteins at 3 weeks old normally results in an active response to the fed protein, as determined by the appearance of serum IgG antisoya antibody. This system thus allows the effects of manipulation on the response to a fed protein to be studied. In animals previously given 1 g of soya protein at birth, the magnitude of the antibody response to soya fed at 3 weeks was decreased, although similar amounts of the fed protein could be detected in serum. In addition, the relative affinity of the dominant interaction between antigen and antibody was reduced in these piglets by almost an order of magnitude. By comparison, the ability of piglets given soya at birth to respond to injected soya was not significantly reduced. These results indicate that the regulation of responses to fed and systemic antigens is largely separate. Very early oral exposure to antigen may affect the ability of neonatal animals to mount immune responses to, specifically, fed proteins while leaving the response to systemic antigen largely intact.

Animals↗

PubMed1994

Use of the short-term inflammatory response in the mouse peritoneal cavity to assess the biological activity of leached vitreous fibers.

We used a special-purpose glass microfiber sample, Johns-Manville Code 100/475, to study the effects of various acid and alkali treatments on biological activity as assessed by inflammation in the mouse peritoneal cavity, the leaching of Si, and the phase contrast optical microscopy (PCOM) fiber number. We used mild and medium treatments with oxalic acid and Tris buffer and harsh treatment with concentrated HCl and NaOH. Mild oxalic acid and Tris treatment for 2 weeks had no effect on any of the end-points, but prolonging the mild oxalic acid treatment time to 2 months reduced the biological activity and the fiber number. Medium oxalic acid treatment reduced the biological activity and the fiber number and caused a loss of Si. Medium Tris alkali treatment reduced the PCOM-countable fibers and the biological activity but did not cause a substantial loss of Si. Harsh treatment with strong HCl did not affect the fiber number or cause leaching but the biological activity was reduced; strong NaOH reduced the fiber number and biological activity, and caused marked leaching of Si. The medium oxalic acid conditions (pH 1.4) were more acid than those found in lung cells but produced the same effects (reduction in fiber number and biological activity) as the more physiological mild treatment (pH 4.0), when prolonged. This study suggests that medium oxalic acid treatment can be used as a short-term assay to compare loss of Si, reduction in fiber number, and change in biological activity of vitreous fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1994

Static progressive stretch to reestablish elbow range of motion.

Static progressive stretch (SPS) is a technique using the biomechanical principle of stress relaxation to restore range of motion (ROM) in joint contractures. Existing techniques such as dynamic splinting and traction rely on a time-dependent material property, creep, which applies a continuous load. Other techniques, such as serial casting and static splinting, are time intensive and usually require assistance by a therapist. This study evaluates SPS via a new orthosis that directly applies SPS incrementally through patient-controlled therapy, allowing for stress relaxation of contracted tissue. Patients used the device in 30-minute treatment protocols. The length of treatment time varied between one and three months. Twenty patients with elbow contractures who had limited success with other treatment modalities including serial casting, dynamic splinting, physical therapy, and/or surgery, underwent SPS using the new orthosis. The increase in motion for the 20 patients in the study averaged 31 degrees (69%). All patients expressed satisfaction, with no complications and no deterioration in ROM at the one-year follow-up evaluation.

Adolescent↗

PubMed1993

Specific immunological unresponsiveness following active primary responses to proteins in the weaning diet of piglets.

Young piglets weaned onto soya diets frequently develop diarrhoea which may have a dietary and/or immunological component. Piglets abruptly weaned onto soya at 3 weeks of age developed levels of serum IgG anti-soya antibodies almost comparable to those induced by injection with soya protein in adjuvant at 7 weeks. In the piglets primed by feeding, no significant further increase in antibody occurred after subsequent systemic injection. In contrast, secondary responses were observed in age-matched animals, previously primed by injection, and primary responses were obtained in previously naive piglets. The results demonstrate the development of specific unresponsiveness to soya proteins in neonates fed soya, despite the occurrence of an initial vigorous immune response to the fed protein.

Administration, Oral↗

PubMed1993

Asbestos fibre length-dependent detachment injury to alveolar epithelial cells in vitro: role of a fibronectin-binding receptor.

A short and a long fibre sample of amosite asbestos were tested for their effects on cells of the human Type 2 alveolar epithelial cell-line A549 in vitro. The long amosite sample was found to cause a rapid detachment of the epithelial cells live from their substratum. At the highest dose, on average 28% of the cells present were detached in this way. Studies on the mechanism of the detachment injury showed that it did not involve oxidants since it was not ameliorated by scavengers of active oxygen species. Neither was the effect reduced by treatment of the fibres with the iron chelator Desferal. Treatments reported to increase the interaction between fibres and cells, serum and poly-L-lysine, did not influence the detachment injury, nor did lung lining fluid. Conversely, the fibronectin tripeptide RGD alone could cause detachment which suggested that a fibronectin-binding integrin was involved. This receptor could be reduced in activity by long fibre exposure, leading to detachment. The detaching effect of fibre could be mimicked by the protein kinase C activator PMA, and so the second messenger system of the cell could also be involved. This type of injury could be important in the pathology associated with exposure to long fibres.

Asbestos↗

PubMed1992

Asbestos-stimulated tumour necrosis factor release from alveolar macrophages depends on fibre length and opsonization.

Fibre length has been shown to be an important factor in the ability of respirable fibres to cause lung fibrosis and cancer. We have reported that a long sample of amosite asbestos is more carcinogenic and fibrogenic than a short sample of similar diameter. These amosite asbestos samples were studied with regard to their ability to stimulate the release of the pro-inflammatory cytokine tumour necrosis factor (TNF) from rat alveolar macrophages in vitro. The long fibre sample was found to stimulate substantially greater release of the cytokine than the short sample. Furthermore, on treatment of the fibres with rat immunoglobulin G (IgG), there was an increase in the ability of both the long and the short sample to stimulate TNF secretion, although the long sample retained by far the greatest activity. Coating of the fibres with a range of other proteins had no substantial effect on their ability to stimulate TNF secretion. Quartz and titanium dioxide (TiO2) were included as control particles and the TNF-stimulating activity of quartz was notably increased by opsonization with IgG. TiO2 showed a similar low activity to that of the short fibre sample of amosite but this again could be modestly increased by opsonization with IgG. The simulation of TNF release caused by treatment with immunoglobulin-opsonized long fibre amosite could be inhibited by treatment of the macrophages with the protein kinase C-inhibitor staurosporine. The study demonstrates a fibre length-related ability to stimulate cytokine secretion by alveolar macrophages, and its enhancement by opsonization with IgG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Variations in the carcinogenicity of tremolite dust samples of differing morphology.

Six samples of tremolite of different morphological type were prepared as dusts of respirable size and used in intraperitoneal injection studies in rats. Three "asbestiform" tremolites produced mesotheliomas in almost all animals, although with significantly different tumor-induction periods. A brittle type of fibrous tremolite which, when manipulated to prepare "respirable dust," produced a sample with relatively few asbestiform fibers remaining nonetheless produced tumors in 70% of rats. Two samples of nonfibrous tremolite produced respirable dust samples containing numerous elongated fragments with aspect ratios greater than 3:1, which therefore fitted the definition of respirable fibers. Both these samples produced relatively few tumors, although one had more long "fibers" than did the brittle tremolite that produced 70% of tumors. This study has therefore demonstrated that different morphologic forms of tremolite produce dusts with very different carcinogenic potential. Carcinogenicity does not depend simply on the number of elongated particles injected, and we need to develop methods of distinguishing carcinogenic tremolite fibers from relatively innocuous tremolite dusts, with similar numbers of elongated particles of similar aspect ratios.

Animals↗

PubMed1991

Vascular smooth muscle structure and juvenile growth in rat intestinal venules.

The morphological structure of individual vascular smooth muscle cells from intestinal venules was evaluated with a combination of quantitative scanning (SEM) and transmission (TEM) electron microscopy techniques. In addition, growth of individual venular smooth muscle cells and of the overall vessel wall was compared from measurements of these variables during the rapid juvenile growth spurt from ages 4 to 6 and 10 to 12 weeks in Wistar-Kyoto rats. SEM revealed that smooth muscle cells of intestinal venules in weanling rats are very long (379 +/- 91 [SD] microns) and wide (6.0 +/- 1.3 microns) and very little further cell enlargement occurs during rapid juvenile growth. TEM studies indicated that passive inner vessel diameter and total muscle layer cross-sectional area of both the largest and intermediate diameter venules of young rats, as well as the percentage of the total wall area as muscle tissue in each venule type, did not significantly increase during body growth. These observations indicate that both the intestinal venules and their smooth muscle cells reach mature dimensions at a very early stage of life. Comparison of intestinal vascular smooth muscle cell dimensions indicates that venular smooth muscle cells are much larger in both cell length and volume than comparable arteriolar smooth muscle cells.

Aging↗

PubMed1991

Dietary antigen handling by mother and offspring.

Sows were fed ovalbumin (OvA) as a novel protein antigen either throughout gestation and lactation (G + L) or during lactation only (L). This resulted in a significant uptake of OvA into blood, colostrum and milk along with a specific IgG response. In piglets from the G + L group, OvA and antibodies to OvA were detected in serum after ingestion of colostrum. In a large proportion of these piglets OvA was still detected at 3 weeks of age. In the L group a significant proportion of the piglets responded to OvA whilst still suckling their mother. At 3 weeks of age all piglets were weaned onto an egg-based diet. A similar uptake of OvA was seen in all piglets but there was no response to OvA in the G + L piglets. In piglets from sows fed only during lactation, however, a rapid IgG anti-OvA response and signs of diarrhoea were seen. The results suggest that factors of immunological importance are passed over from mother to offspring and it is proposed that immunological experience of dietary antigens by the mother is important for a 'safe' tolerance induction in her offspring.

Animals↗

PubMed1991

Experimental studies in rats on the effects of asbestos inhalation coupled with the inhalation of titanium dioxide or quartz.

Rats were exposed for 1 year, with a 2-year follow-up, to dust clouds consisting of a mixture of amosite or chrysotile asbestos with either titanium dioxide or quartz. The addition of titanium dioxide to asbestos did not increase levels of pulmonary fibrosis above the amounts produced by chrysotile or amosite alone. Quartz, however, greatly increased fibrosis above that produced by the asbestos types alone. Both particulate dusts caused an increase in the numbers of pulmonary tumours and mesotheliomas compared to asbestos alone but while tumours in animals treated with asbestos and quartz tended to occur earlier than tumours with asbestos alone, in animals treated with dusts containing titanium dioxide, tumour production occurred later than with asbestos alone. In animals treated with mixtures of asbestos and quartz, there was evidence of increased transport of fibres across the visceral pleural surface and this may be associated with the finding of a higher proportion of pleural mesotheliomas than previously reported in experimental inhalation studies from any laboratory using the main asbestos varieties. The presence of particulate dusts made little difference to the amounts of amosite fibre retained in the lung tissue but, with chrysotile, titanium dioxide appeared to increase retention while quartz reduced it.

Animals↗

PubMed1991

Mesothelioma dose response following intraperitoneal injection of mineral fibres.

The relationship between injected dose and the development of peritoneal mesotheliomas has been examined in rats using the UTCC standard reference samples of chrysotile, crocidolite and amosite as well as a sample of fibrous erionite from Oregon. Doses injected into the peritoneal cavity ranged from 0.005 to 25 mg and with each dust a clear dose response was found. The proportion of animals developing tumours increased with the amount of dust injected while the tumour induction period was reduced. When times to death from mesothelioma were analysed using standard hazard models, erionite was the most carcinogenic dust by mass followed by chrysotile, amosite and crocidolite. The hazard slopes for erionite, chrysotile and crocidolite, over the range of doses examined, were parallel while the slope for amosite was shallower. The relative hazards for the various dust types were also examined with dose expressed as the number of injected fibres in a range of sizes as measured by SEM. No combination of fibre dimensions was found at which the hazard for the four dust types was equal although when dose was expressed as the number of long fibres injected (> 8 microns in length) the hazard slopes for chrysotile, crocidolite and amosite were relatively close. The hazard level of erionite remained well above the other dust types regardless of how the dose was expressed.

Animals↗