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Biomedical subjects

G George

Publications and source records attributed to G George.

At least 37 records · Page 2Linked to original sources
PubMed1990

[The dose precision of PMSG for gilts and old sows in procedures for ovulation synchronization. 2. Organometric and histometric findings after diagnostic slaughtering].

An account is given in this paper of organometric and histometric findings obtained, on three farms, N, B, and D, from ovaries, uteri, and oviducts of biotechnologically treated gilts and adult sows, using differentiated PMSG doses (600, 800, and 1,000 IU on gilts and adult sows of N and B; 500, 1,000, and 1,500 IU on gilts of D). Ovulation potentials were within the biological normal in response to low dosage (with an average of 12 to 15 follicles in gilts and 17 in adult sows). The 800 IU dose caused significant stimulation, which had to be interpreted as overstimulation for PMSG-sensitive probands of N. Ovarian reaction and induced cycle should by duly considered for interpretation of histometric findings.

Animals↗
PubMed1990

[The dose precision of PMSG in young and old sows in the process of biotechnical ovulation synchronization. 1. Comparison of diagnostic laparotomy].

Treatment was applied, on two farms, to 272 gilts and 169 adult sows, 24 hours after discontinuation of Suisynchron application to the gilts or weaning of piglets of adult sows. Included were 600, 800 or 1,000 IU of PMSG for the gilts and 750, 1,000 oder 1,250 IU of the same batch (Pregmagon-Dessau) for the adult sows for ovarian stimulation. This was followed by application of 500 IU of HCG to the gilts or 300 micrograms Gn-RH vet. "Berlin-Chemie" + 300 IU HCG to the adult sows for synchronised ovulation. Laparotomy was performed on the gilts on the fifth day from PMSG application and on the adult sows on the fourth day. Average ovariotropic stimulation was "mild" in response to lower doses (14.8 follicles in gilts and 20.4 follicles in adult sows) but was "pronounced" in response to medium doses (19.4 or 22.7 follicles, respectively). The pharmacological concept of "mild" exogenic ovarian stimulation by low dosage at the threshold of effectiveness should deserve more attention, last but not least, for breeding aspects. The two groups of animals on both farms differed considerably from one another with regard to reactivity, which cannot be etiologically interpreted for the time being.

Animals↗
PubMed1989

Nuclear imaging and the assessment of human Fc receptor function: studies in systemic lupus erythematosus.

In vivo immune clearance of immunoglobulin G sensitized autologous erythrocytes (rbc) was studied in nine patients who fulfilled American Rheumatism Association (ARA) criteria for systemic lupus erythematosus (SLE). Opsonized rbc were radiolabelled with technetium 99. The rate of radioactive blood clearance was measured, as was organ-specific radioactive uptake utilizing area-of-interest (AOI) measurements in a computerized scintigraphic imaging system. It was shown that dynamic quantitation of an AOI corresponding to the heart generated time-activity curves which approximated blood-clearance curves. Calculation of first order clearance (min per 50% decrease in counts) showed a highly significant correlation between rates derived from heart AOI curves and those derived from blood-clearance curves (r = 0.9483, P = 0.0003). Clearance curves showed a monoexponential slope in most patients. Further exploration of organ-specific AOI curves showed that percent splenic uptake and the nature of the splenic uptake curves varied between patients. These studies point toward a variable splenic role in Fc receptor function for SLE patients and further demonstrate the utility of nuclear imaging in studying immune clearance.

Adult↗
PubMed1989

Marketing a practical health care policy for the United States.

A policy for universal health care in the United States has been proposed by leading health planners. All citizens of the United States should be entitled to basic health care of adequate quality. Basic care should include physicians, hospitals, and clinic services, emergency and preventive care, and certain other treatments and services. Key to this practical health care policy is the method by which it will be financed. This policy combines several widely discussed financial methods such as Medical Individual Retirement Accounts, catastrophic health insurance, and the combination of what is now known as Medicare and Medicaid into one umbrella package. Active competition within the health care delivery system is essential. To prepare the health care consumer for this competitive environment, an active marketing program by providers, corporations, and all levels of government is basic. For such a policy to be implemented, it must be marketed to the legislature, professional organizations within the health and insurance fields, to educators and to the public.

Community Participation↗
PubMed1989

[Experimental endocrinological studies in gilts near the time of ovulation using Gn-RH vet. "Berlin Chemistry"].

Knowledge of endocrine processes in pro-oestrus and oestrus in conjunction with physiological alterations is of greatest importance to biotechnological control of follicular maturation and ovulation. Methods of hormonal analysis and ovarian diagnosis were used to check on the effectiveness of Gn-RH vet. "Berlin-Chemie" for induction of the luteinising hormone (LH) peak and ovulation. Release in gilts of LH was found to depend on dosage, after 100, 300, and 900 micrograms Gn-RH had been administered at 3 p.m. on the 4th day after synchronisation of ovulation. LH release and induction of ovulation due to these variants were insufficient in some of the animals. Ovulation was then decisively improved in animals with LH peak by subsequent injection of 300 or 900 micrograms Gn-RH at 8 a.m. on the 5th day. Repetitive injections of 300 micrograms Gn-RH at 8 and 8.45 a.m. on the 5th day did not trigger off increased LH release from the pituitary gland. The Gn-RH effect was substantially improved by use of an absorption-retarding preparation (polystyrene sulphonic acid).

Animals↗
PubMed1988

Pulmonary macrophages are attracted to inhaled particles through complement activation.

Pulmonary macrophages play a central role in clearing inhaled particles from the lung. Previously, we showed that inhaled asbestos fibers activate complement-dependent chemotactic factors on alveolar surfaces to facilitate macrophage recruitment to sites of fiber deposition. In the studies presented here, we have tested a variety of inorganic particles for complement activation in vitro and correlated these data with results on particle-induced macrophage accumulation in vivo. We found that significant chemotactic activity was activated in rat serum and concentrated lavaged proteins by chrysotile and crocidolite asbestos, iron-coated chrysotile asbestos, fiberglass, and wollastonite fibers, as well as by carbonyl iron and zymosan particles. Ash from the Mt. St. Helens volcano did not induce chemotactic activity in either the serum or lavaged proteins. Rats were exposed to brief aerosols of each of the particles listed above (except zymosan). All the particle types studied were deposited primarily at first alveolar duct bifurcations. In addition, all of the particles, except Mt. St. Helens ash, induced at 48 h postexposure significant accumulations of macrophages at these sites. Time-course studies of carbonyl iron particle exposure demonstrated that iron induced a rapid macrophage response, but both particles and phagocytic macrophages were cleared from alveolar surfaces within 8 days after exposure. The Mt. St. Helens ash induced no macrophage accumulation at any time postexposure. We conclude that particles with a wide variety of physical characteristics are capable of activating complement and consequently attracting macrophages, both in vitro and in vivo. We suggest that complement activation is a mechanism through which pulmonary macrophages can detect inhaled particles on alveolar surfaces.

Animals↗
PubMed1987

Sialic acid mediates the initial binding of positively charged inorganic particles to alveolar macrophage membranes.

Pulmonary macrophages phagocytize inhaled particles and are postulated to play a role in the development of pulmonary interstitial fibrogenesis. The basic biologic mechanisms through which inhaled particles bind to macrophage membranes and subsequently are phagocytized remain unclear. We hypothesize that positively charged particles bind to negatively charged sialic acid (SA) residues on macrophage membranes. Alveolar Macrophages (AM) were collected by saline lavage from normal rat lungs. The cells adhered to plastic coverslips in serum-free phosphate buffered saline at 37 degrees C for 45 min and then were maintained at 4 degrees C for the binding experiments. Even distribution of SA groups on AM surfaces was demonstrated by scanning electron microscopy of wheat germ agglutinin (WGA) conjugated to 50 nm gold spheres. The WGA is a lectin that binds specifically to sialic acid, and pretreatment of AM with this lectin prevented the binding of positively charged carbonyl iron (C-Fe) spheres, aluminum (Al) spheres, and chrysotile asbestos fibers to AM surfaces. Limulus protein, another lectin with binding specificity for SA, similarly blocked the binding of positively charged spheres and chrysotile asbestos fibers but not negatively charged glass spheres or crocidolite asbestos fibers. Con A and ricin, lectins that bind to mannose and galactose residues, respectively, did not block particle binding. When both positively charged iron spheres and negatively charged glass spheres were prebound to AM membranes, subsequent treatment with WGA displaced only the positively charged spheres from macrophage surfaces. Con A and ricin had no effect on prebound positively charged C-Fe and Al spheres.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Parasuicide: interaction between inadequate parenting and recent interpersonal stress.

We report a controlled study in which we searched for links between early family adversity and recent interpersonal stress in parasuicidal patients. Our subjects reported fewer adverse experiences in childhood than did the younger, predominantly female, patients investigated in previous studies. Nevertheless, 47% of our parasuicidal group, as compared to 19% of control subjects, reported a sequential pattern of relationship difficulties starting in childhood. The pattern of early exposure to neglectful and overprotective parenting followed by recent conflict or separations in adulthood was found to discriminate most clearly between the parasuicidal and control groups. We suggest that factors such as low self-esteem, a sense of helplessness in the face of adversity and an abiding insecurity in intimate relationships may variously account for this heightened vulnerability. We conclude that a history of adverse relationships beginning in childhood should alert primary care-givers to the risk of suicidal behaviour in patients who are exposed to distressing separations or interpersonal conflict.

Adult↗
PubMed1986

Effects of silica on the composition of the pulmonary extracellular lining.

The effects of intratracheally injected silica on lung weights and on alveolar macrophages, polymorphonuclear leukocytes, phospholipid, protein, N-acetyl-beta-glucosaminidase, and alkaline phosphatase of the extracellular lining of rat lungs were studied as functions of dose and time. All of these parameters increased with time up to 12 days after a single injection of silica (200 mg/kg) and showed a dose dependence in their responses. Extracellular soluble protein increased 19.8-fold from 1.9 to 37.6 mg/pair of lungs. The composition of the extracellular soluble protein was very similar to that found in normal lungs as determined with two-dimensional-polyacrylamide gel electrophoresis. Although most of the soluble proteins in lavage effluents were similar to those found in serum, several serum proteins were absent, indicating that the selectivity of the lungs for certain serum proteins was maintained after treatment with silica. Increases in extracellular soluble proteins could not be accounted for by damage to the blood/air barrier. Extracellular phospholipid increased 12.1-fold from 1.74 to 21.1 mg/pair of lungs. The phosphatidylcholine content of this phospholipid resembled that of normal pulmonary surfactant but was different from that in free cells lavaged from the lungs of control and silica-treated rats. Increases in extracellular phospholipid were probably due to silica effects on the surfactant system and not to destruction of or release by free cells in the alveoli. N-Acetyl-beta-glucosaminidase and alkaline phosphatase increased approximately 33- and 6-fold, respectively, in response to silica. The number of alveolar macrophages and polymorphonuclear leukocytes increased 1.5- and 75-fold, respectively. Calculation of partial correlations revealed statistically significant relationships among extracellular phospholipids, soluble proteins, and the two hydrolytic enzymes, suggesting that these components were being released into the lung lining from a common source or by a common mechanism.

Acetylglucosaminidase↗
PubMed1986

Outbreak of pulmonary tuberculosis in children.

A case of miliary tuberculosis in a 4-year-old child led to contact tracing, revealing 32 children with evidence of tuberculous infection. 3 adult cases were also identified. The source case was a mother who passed on the infection at two Christmas parties. Limited exposure to the organism caused infection, suggesting a virulent strain and a susceptible subgroup. A range of complications of primary tuberculosis in children was seen. Minor side-effects of the chemotherapeutic agents occurred in most children but only 3 suffered substantial toxic effects. The limited range of agents marketed in a presentation suitable for young children was a serious difficulty.

Adolescent↗
PubMed1986

Time course of chemotactic factor generation and the corresponding macrophage response to asbestos inhalation.

Inhalation of asbestos fibers causes a progressive fibrotic lung disease in humans and animals. Pulmonary macrophages are associated with asbestos exposure and have been implicated as significant mediators of the pathogenic process. In previous studies, we showed that macrophages are attracted to sites of asbestos fiber deposition, i.e., alveolar duct bifurcations. We also showed that macrophages accumulated at these sites as the result of asbestos-induced activation of complement proteins on alveolar surfaces, consequently producing C5a, a chemotactic factor for macrophages. In the present study, we have demonstrated the time course of chemotactic factor generation and the corresponding macrophage response in vivo. A complement-dependent chemotactic factor for macrophages was activated during a 3-h exposure to asbestos and reached maximal activity by 3 h postexposure. Macrophage accumulation followed and reached a maximal amount by 24 h postexposure. Rats decomplemented with cobra venom factor exhibited a significant reduction in macrophage accumulation, but the macrophage response ensued when serum complement returned to normal. Approximately 30% of the macrophages lavaged from complement-normal, asbestos-exposed animals contained fibers, whereas only half as many macrophages from decomplemented rats contained asbestos. A small but significant increase in lavaged lung protein was measured in asbestos-exposed animals. Evidence supports the concept that complement proteins on alveolar surfaces are derived from normal transudation of serum components from the pulmonary vasculature. Increased serum transudation could provide a source of alveolar complement that sustains the generation of a chemotactic factor for macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Inhaled asbestos activates a complement-dependent chemoattractant for macrophages.

Pulmonary macrophages migrate to the sites where inhaled chrysotile asbestos fibers initially are deposited (i.e., surfaces of alveolar duct bifurcations). These macrophages have been shown to form a major component of an early asbestos-induced interstitial lesion in rats. In this report, we describe a potential mechanism by which macrophages are attached to these sites of fiber deposition. Chrysotile asbestos fibers used in vitro activate complement proteins in peripheral blood serum and in lavaged cell-free lung proteins. After brief inhalation of chrysotile asbestos, fluids lavaged from the lungs of exposed rats contain substantial chemotactic activity for macrophages compared to fluids from sham-exposed animals (p less than 0.01). We hypothesize that this chemotactic activity is derived from complement activated by inhaled asbestos on alveolar surfaces. This contention is supported by the following observations. Production of chemotactic activity by asbestos in vitro in serum or in lavaged lung fluids was blocked by complement inhibitors. Fractionation, by molecular sieve chromatography, of serum proteins and concentrated proteins lavaged from the lungs of asbestos-exposed rats showed that chemotactic activity was detected in the 14,000- to 18,000-dalton range. This fractionation profile is similar to C5a, the chemotactic product of complement activation. Rats treated with cobra venom factor to deplete circulating complement as well as complement-deficient mice demonstrated significantly depressed macrophage accumulation at sites of asbestos deposition. Pulmonary macrophages are the cells that form the initial inflammatory response to asbestos inhalation. Our findings support the hypothesis that asbestos fibers, and possibly other inhaled particulates, activate complement-derived chemotactic activity on alveolar surfaces. Consequently, macrophages are attracted to the alveolar duct bifurcations where inhaled asbestos fibers are deposited, and this is where the initial lesion of asbestosis is manifested.

Animals↗
PubMed1984

Pathogenesis of capsular opacification after extracapsular cataract extraction. An animal model.

Opacification of the posterior capsule is the most common post-operative complication of extracapsular cataract surgery. We studied the sequential changes in the posterior capsule of the aphakic cat and monkey after extracapsular surgery using light microscopy, scanning electron microscopy, and transmission electron microscopy. In the cat, but not the monkey, there was proliferation of a pigment-containing membrane arising from the iris root and ciliary body, and extending onto the residual lens capsule. In both animals there was transformation of residual lens epithelial cells to fibroblasts which contain contractile elements (myofibroblasts) and are associated with collagen deposition. In the cat, pigment epithelial cells from the iris or ciliary body, as well as the transformed lens epithelial cells, contributed to late opacification of the posterior capsule.

Animals↗
PubMed1984

The pulmonary extracellular lining.

The extracellular lining of the lungs is reviewed. The pulmonary extracellular lining is a complex mixture of phospholipids, proteins and carbohydrates which is absolutely essential for the maintenance of normal pulmonary functions such as gas exchange. Without the lining the lungs would collapse. Alterations in the pulmonary extracellular lining may underlie some disease conditions induced by toxic agents, especially those which interfere with the formation of pulmonary surfactant. The extracellular lining could be used to detect and monitor damage and disease caused by agents toxic to the lungs. The lining contains many hydrolytic enzymes which may act to detoxify certain toxic agents such as those which contain ester groups. The pulmonary extracellular lining could play a significant role mediating the toxic action of inhaled agents as well as the removal of those agents from the lungs.

Animals↗