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Biomedical subjects

B G Miller

Publications and source records attributed to B G Miller.

At least 73 records · Page 4Linked to original sources
PubMed1990

The effect of feeding lovastatin and colestipol on production and cholesterol content of eggs.

The purpose of the present study was to determine whether feeding lovastatin or colestipol, or both, to laying hens would decrease the concentration of cholesterol in eggs. Forty-eight White Leghorn hens (69 wk of age) were allocated randomly to one of four groups. For 5 wk, the birds were fed: 1) a control diet; 2) diets supplemented with 35 mg of lovastatin per kg of feed; 3) 11.7 g of colestipol per kg of feed; or 4) both 35 mg of lovastatin and 11.7 g of colestipol per kg of feed. Drug feeding did not affect egg production or the concentration of cholesterol in the yolk, muscle, or liver. Lovastatin residue was found in liver samples from hens receiving lovastatin, but no lovastatin residue was found in the muscle, egg-white, or egg-yolk samples from hens on any treatment. These findings suggest that lovastatin or colestipol, or both, fed at relatively low amounts do not decrease the concentration of cholesterol in egg yolk and do not depress egg production.

Animal Feed↗
PubMed1990

An ethnographic view: positive consequences of the War on Poverty.

Life history data from Coast Salish tribes of Washington state reveal that federal War on Poverty programs produced important results that routine analysis has failed to uncover. The Comprehensive Training and Employment Act and the Indian Community Action Project provided income that enabled family networks to serve as centers of moral and financial support for members engaged in therapeutic work and provided training opportunities for a generation of leaders who are now instrumental in attracting funding for mental health programs.

Cultural Characteristics↗
PubMed1989

Circulating lymphocytes, neutrophils and immune complexes in pigs after feeding.

There are reports in the literature claiming that pigs experience a lymphopenia after feeding. This is not observed in other species. We set out to investigate this phenomenon because of the unusual route of lymphocyte recirculation in pigs. for it suggested that this might be a specific response to dietary antigens. We were unable to confirm this phenomenon. A lymphopenia was observed in both test and control groups as a non-specific response to restraint and blood sampling. In contrast, feeding was associated with a significant neutrophilia (mean 58%, P less than 0.002). There were no increases in circulating IgA, IgG or IgM immune complexes after feeding but IgG immune complexes remained at a higher level than in the control group.

Animals↗
PubMed1989

Protein secretion by the endometrium during pregnancy in the ewe.

Mature Merino ewes were surgically prepared so that after mating they became unilaterally pregnant. Ewes were killed between days 91 and 124 of pregnancy and the uterine milk was collected from the ligated uterine horn. Explants of intercaruncular and intercotyledonary endometrium were collected from the ligated and unligated uterine horns, respectively, and incubated in the presence of L-[4,5-3H]leucine to determine in vitro rates of protein synthesis and secretion. Protein:DNA and DNA:wet tissue ratios were also determined in the explants from some ewes. The proteins secreted in vitro and those present in uterine milk were partially characterized, using several procedures. Antisera raised in rabbits against uterine milk and absorbed against plasma from an ovariectomized ewe were used to detect uterine milk antigens in a variety of tissues and plasma. An average of 150 +/- 26 mL of creamy coloured uterine milk containing 30.7 +/- 4.6 mg mL-1 protein was recovered from 14 ewes. The rates of protein synthesis and secretion in vitro and the protein:DNA ratio were all higher in intercotyledonary than in intercaruncular endometrium, but the predominant radiolabelled protein(s) secreted in vitro by both types of endometrium was shown by gel filtration to have a molecular weight of approximately 60 kDa. This 'uterine pregnancy protein' was not secreted by endometrial explants from a non-pregnant ewe. Uterine milk contained a substantial amount of 60 kDa protein. The molecular weight and lack of sub-unit structure of the 60 kDa fraction of proteins secreted in vitro was confirmed by SDS-acrylamide electrophoresis and density gradient centrifugation. Pronase treatment confirmed the proteinaceous nature of the 60 kDa fraction, and heparin-Sepharose affinity chromatography showed that the predominant secreted protein(s) in this fraction was a glycoprotein. In immuno-double-diffusion tests antisera prepared against uterine milk produced a number of precipitation bands against both uterine milk and culture medium (after incubation of endometrial explants from a pregnant ewe) and a single band against allantoic fluid, but did not react with plasma from an ovariectomized ewe or a day-124 pregnant ewe or its fetus. The antisera did not react with lung, kidney or liver from the same pregnant ewe or with uterine flushings from a non-pregnant ewe. In immuno-electrophoresis tests, at least eight distinct antigens were detected in uterine milk and three of these were also present in allantoic fluid.

Animals↗
PubMed1989

Some biological activities of cronolone and medroxyprogesterone acetate in the uterus of the sheep, mouse and rabbit.

Cronolone (9 alpha-fluoro-11 beta-hydroxy-17 alpha-acetoxypregn-4-ene-3,20-dione) is widely employed to regulate breeding activity in the ewe, but its biological activity in the uterus of this and most other species has not been studied. In this study several in vivo uterus-related activities of cronolone have been examined in the sheep, mouse and rabbit. In some experiments the corresponding activities of medroxyprogesterone acetate (6 alpha-methyl-17 alpha-acetoxypregn-4-ene-3,20-dione, MAP) were also examined. Cronolone maintained pregnancy in ovariectomized ewes but not in ovariectomized mice and rabbits; it terminated pregnancy in some mice and in all rabbits that were receiving daily progesterone treatment. Cronolone could not sensitize the mouse uterus for the induction of the decidual-cell reaction or block the induction of such sensitivity by progesterone, but did support limited growth of the oil-stimulated horn after sensitization with progesterone. Cronolone induced uteroglobin secretion by rabbit endometrium. It was concluded that, whereas MAP is a potent progestogen in the sheep, mouse and rabbit, cronolone is a progestogen in the sheep and rabbit only. In the mouse and especially the rabbit, cronolone has other, non-progestational activities, which block pregnancy.

Animals↗
PubMed1989

In vitro binding of progesterone, cronolone and medroxyprogesterone acetate to uterine progesterone receptors of sheep, rabbit and mouse.

Various aspects of the binding of the synthetic progesteongens, cronolone (9 alpha-fluoro-11 beta-hydroxy-17 alpha-acetoxypregn-4-ene-3,20-dione) and medroxyprogesterone acetate (6 alpha-methyl-17 alpha-acetoxypregn-4-ene-3,20-dione, MAP) to uterine cytosol progesterone receptors of the sheep, rabbit and mouse were studied, in an attempt to explain interesting species differences in the biological activity of these steroids. For the sheep, data for binding-site concentration, relative binding affinity (RBA), dissociation constant (Kd) and rates of association and dissociation indicate specific binding of cronolone to the progesterone receptor and these would seem to explain in part the high progestational activity of cronolone in this species. By contrast, with the mouse, there was only a low level of specific binding of cronolone and this appears to explain its inability to maintain pregnancy in this species. Results for the binding activity of cronolone in rabbit uterus were similar to those for the sheep and thus inability of cronolone to maintain pregnancy in the rabbit is not explained by a failure to bind the progesterone receptor. Species differences in binding to the progesterone receptor were also seen with MAP where the RBA, with respect to progesterone, was high in the sheep and rabbit and lower in the mouse. The results, however, do not relate directly to the progestational activity of MAP in these species. Overall, the data indicate that species differences in the binding activity of steroid receptors constitute one factor that causes species-dependent variation in biological responses to progestogens.

Animals↗
PubMed1988

Histochemistry of mucins of pig intestinal secretory epithelial cells before and after weaning.

Two histochemical staining techniques, Alcian blue/PAS and high-iron-diamine/Alcian blue, which differentiated neutral from sulphated and sialylated acid mucins were applied to sections of duodenum, ileum, caecum, colon and rectum from pigs aged one day, 3 weeks and 10 weeks. In each age group, sulphated-acid mucins predominated at all sites, particularly in the large intestine. In both the small and the large intestine, non-sulphated mucins occurred mainly at the bases of the crypts. Neutral mucins occurred in a few goblet cells in crypts and villi, either alone or together with acid mucins; neutral mucins increased away from the bases of the crypts. No changes were noted in the caecum, colon or rectum of pigs one, two, 5 or 13 days after weaning onto a diet containing soya protein. In the small intestine, there was a transient increase in the numbers of goblet cells in the crypts and villi, a relative increase in sulphated and a decrease in non-sulphated acid mucins and a change in the distribution of sulphated mucins in the crypts. No change in proportions of neutral and acid mucins was detected.

Animals↗
PubMed1988

Development of sheep embryos in vitro in a medium supplemented with different serum fractions.

Sheep embryos will generally develop into expanded blastocysts in vitro only in culture media supplemented with serum or serum components. In order to better understand how serum supports embryo development, a batch of ovine serum was fractionated by (a) ultrafiltration into two components containing substances with molecular weights greater and less than 10 Kd (kilodaltons), and (b) gel filtration into protein fractions 1, 2 and 3, containing groups of proteins with mean molecular weights of about 500, 150 and 65 Kd, respectively. The principal protein in fraction 3 was albumin. Day 6 sheep morulae were cultured in vitro for 48 hours in a bicarbonate-buffered salt solution supplemented with various concentrations of ovine serum or of these components or protein fractions of serum. Morulae could develop to fully expanded blastocysts in medium supplemented with whole serum or with the greater than 10 Kd component or protein fraction 3 only, but could not develop in medium supplemented with the less than 10 Kd component only or with the less than 10 Kd component and protein fractions 1 or 2. However, the proportion of embryos that developed fully in medium supplemented with the greater than 10 Kd component or protein fraction 3 was increased by adding the less than 10 Kd component of serum to the medium. The addition of protein fraction 2 decreased the proportion of embryos that developed to expanded blastocysts in medium containing protein fraction 3 and the less than 10 Kd component, but not in medium containing whole serum. Since the compositions of different sera may vary markedly, these results suggest (a) reasons why different sera vary in their ability to support embryo development in vitro, and (b) factors which may influence development of the sheep embryo in the uterus, where plasma proteins comprise nearly all the protein in the fluid bathing the embryo.

Animals↗
PubMed1988

Development of sheep embryos in vitro in a medium supplemented with different batches of serum albumin.

Variability in different lots of commercial serum albumin affects mammalian embryo development in culture. The composition of commercial preparations of ovine, bovine and defatted bovine serum albumin and a fraction of ovine serum containing proteins with a mean molecular weight of 65 kDa (fraction 3) was examined by polyacrylamide gel electrophoresis. All preparations were heavily contaminated with serum proteins other than albumin. Day-6 sheep morulae were cultured for 48 h in a basal bicarbonate-buffered salt solution supplemented with the commercial preparations of ovine, bovine or defatted bovine serum albumin. These three albumin preparations differed in their abilities to support the development of morulae into expanded blastocysts, but these differences disappeared when the basal medium was also supplemented with a component of ovine serum containing substances with molecular weights of less than 10 kDa. In the latter case, the three commercial albumin preparations and fraction 3 of ovine serum all supported full development in about 40-60% of morulae.

Animals↗
PubMed1988

Weak associations in occupational epidemiology: adjustment for exposure estimation error.

Epidemiological studies often estimate the health effects of occupational exposures by multiple regression techniques. The standard theory of regression analysis is based on the assumption that the explanatory variables are known without error, and it has long been realised that departures from this assumption will lead to underestimation of the true regression coefficients. In reality, there may be considerable imprecision in the measurement of individuals' exposures to hazards in the workplace, but this is seldom taken into account in analyses. We therefore studied the effect of allowing for imprecision in the exposure estimate with more sophisticated statistical methods, using lung function data from a sample of 348 British miners exposed to mixed coal dust, over an eight-year period. Change in lung function over an eight-year period was regressed on cumulative dust exposure, weight, age and smoking habits. The error in the exposure estimation was assumed to be up to 30% of the total varience of the distribution of the exposure. Adjustment of the regression coefficients of lung function change on dust exposure for the estimation error using linear structural relationships increased the regression coefficient more than threefold compared with those calculated by standard regression analysis. The adjustment led to a change of the coefficients of age as well. The results indicate that a serious underestimation of the relation between lung function change and occupational exposure may occur, which might lead to false interpretations about the relative importance of the occupational exposure as a determinant of disease.

Adult↗
PubMed1987

The immune response to dietary antigens and its influence on disease susceptibility in farm animals.

Transient hypersensitivity reactions of the intestinal immune system to dietary antigens result in increases in enterocyte turnover and villous atrophy. These changes occur in the intestine of the post weaned piglet and precede the proliferation of E. coli and the development of post-weaning diarrhea. We therefore postulated that a transient cell mediated immune response to dietary antigens may increase susceptibility to disease. The interaction of dietary and microbial antigens upon the gut immune system has been investigated in mice and pigs and it has been shown that both exert powerful regulatory effects upon each other.

Adjuvants, Immunologic↗
PubMed1987

Cell and wall morphology of intestinal arterioles from 4- to 6- and 17- to 19-week-old Wistar-Kyoto and spontaneously hypertensive rats.

To determine whether vascular smooth muscle cells around intestinal arterioles of various sizes undergo comparable changes in spontaneously hypertensive rats, 4- to 6-week-old (n = 10) and 17- to 19-week-old (n = 10) rats from the Wistar-Kyoto and the spontaneously hypertensive strains were used to study the external morphology of vascular smooth muscle cells by scanning electron microscopy and the vessel wall cross-sectional characteristics by light microscopy. At the time of fixation all vascular tone had been abolished. Scanning electron microscopy analysis revealed that all Wistar-Kyoto and spontaneously hypertensive rats at a given age have spindle-shaped vascular smooth muscle cells of comparable length and longitudinal width for a given branching order of arterioles. However, normal maturation is associated with elongation and widening of the vascular smooth muscle cells. Light and scanning electron microscopy indicated that a monolayer of vascular smooth muscle cells, wrapped at almost 0 degree to the vessel's radial axis, is maintained in adult spontaneously hypertensive rats. The radial thickness of this vascular smooth muscle cell monolayer was significantly (p less than 0.025) increased for only the largest arterioles of young and adult spontaneously hypertensive rats. This radial thickening of individual vascular smooth muscle cells increased the muscular component of the wall area for the largest arterioles by about 50% in adult spontaneously hypertensive rats. Other smaller submucosal arterioles of young and adult spontaneously hypertensive rats had normal vessel wall and vascular smooth muscle cell characteristics. These data indicate that hypertrophy in the smooth muscle cell's radial dimension is the primary morphological change in intestinal arterioles of spontaneously hypertensive rats. However, the vascular smooth muscle cell hypertrophy is confined to the largest arterioles such that the remaining smaller arteriolar vessels in the spontaneously hypertensive rat retain a normal smooth muscle cell and overall wall morphology.

Aging↗
PubMed1987

Exposure of vascular smooth muscle cells for analysis with the scanning electron microscope.

There has been interest in using the scanning electron microscope (SEM) to study the structure of tissues obscured by other cellular or non-cellular elements almost since the SEM was first used to examine biological tissues. Such interest includes the vessel wall and, in particular, the vascular smooth muscle cells. This paper presents a review of the three basic methodologies that have been employed to allow examination of the vascular smooth muscle, 1) blunt dissection, 2) digestion and 3) microdissection. Discussion of other perivascular elements was not a focus of this review. Also presented is the application of these different methodologies to different pathophysiologic conditions.

Animals↗
PubMed1986

Epidemiologic studies of Scottish oil shale workers: III. Causes of death.

In a mortality study of a population of 6,359 male Scottish oil shale workers, the vital status of 6,145 (96.6%) was determined. Sufficient data on occupational histories for analyses of mortality in relation to jobs held were available for 6,064 (95.4%) of the workers. No significant excess of mortality from any disease was found in relation to any jobs in the industry. Comparison of the mortality experience of those 3,161 men who joined the population prior to 1953 with that of the whole Scottish population showed an excess of deaths from skin cancer but no significant excess that was due to other disease. Comparisons with the population of the counties in which the industry was situated showed no significant excess of deaths from any cause examined. A case-control study of lung cancer in the shale area showed no excess risk of this disease in association with work in the industry.

Fuel Oils↗
PubMed1986

Morphological evaluation of vascular smooth muscle cell: length and width from a single scanning electron micrograph of microvessels.

Accurate three-dimensional data on the structure of vascular smooth muscle cells is essential for understanding the microvascular system in both normal or disease conditions. The laborious serial reconstruction methods have limited the amount of data collected on the structure of individual vascular smooth muscle (VSM) cells. The circumferential viewing of whole vessel segments via scanning electron microscopy provides an alternative approach, but even this technique is highly specialized and tedious. This study presents a simplified method to determine the average cell length and width of individual VSM cells by using only one view of a microvessel (single view). The vessels do not have to be isolated for circumferential viewing and can be left in their host tissue if desired. Values for the average VSM cell length and width were obtained by both circumferential- and single-view approach on the same vessels. The average cell length and width obtained from the single-view method (using one-third circumference) duplicated the mean length and width measurements obtained by circumferential viewing.

Animals↗
PubMed1986

Microvascular smooth muscle cell quantitation from scanning electron microscopic preparations.

A morphometric method to analyze scanning electron micrographs (SEM) of microvascular smooth muscle cells (SMC) is validated using intestinal arterioles. Features easily obtained from these microvasculature preparations are counted (number of tapers and number of complete wraps in the central 87% of the vessel, which is one-third of the vessel's circumference) or measured (vessel diameter and vessel segment length). These data allow the determination of wraps around the values as determined by circumferential examination and quantitation of the vascular segment or an alternative SEM quantitation method (Miller et al., 1986). The method described herein provides a relatively easy way to determine microvascular SMC parameters.

Animals↗
PubMed1986

Effects of the inhalation of dusts from calcium silicate insulation materials in laboratory rats.

The effects of respirable dust from three commercially produced calcium silicate insulation materials were examined in laboratory rats by long-term inhalation and injection techniques. These calcium silicate products have been used as replacements for asbestos in the insulation of the engine rooms of ships, and the particle size distribution of the dust clouds generated for the experimental study closely matched those found in ships during the installation of this type of material. One year of exposure to a dust cloud of 10 mg/m3 of respirable dust had no discernible effect on the length of survival of treated animals compared to controls. No pulmonary lesions were found that appeared associated with the inhalation of calcium silicate per se, but one sample did contain significant amounts of quartz and this did produce a few small pulmonary nodules. While two small pulmonary neoplasms, one malignant and one benign, were found in dusted animals, neither was the cause of death, and the incidence was not significantly different from the control group where no tumors were found. One peritoneal mesothelioma was found in an animal from one of the inhalation groups, but this was considered to be a spontaneous tumor as none of over 100 animals injected intraperitoneally with 25 mg of calcium silicate developed these tumors. While the white blood cell count of dusted animals, compared to controls, was significantly raised in all treated groups at the end of the dusting period, these figures were within the published normal ranges for laboratory rats. It was concluded that the three tested calcium silicate products were harmless to the rats of this species at the doses tested.

Animals↗