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Biomedical subjects

G Guy

Publications and source records attributed to G Guy.

At least 73 records · Page 4Linked to original sources
PubMed1989

Evidence of enhanced storage capacity in adipose tissue of genetically fat chickens.

The storage capacity for plasma triglyceride in abdominal adipose tissue has been investigated in two lines of chickens selected for either high or low adiposity (fat line and lean line, respectively). Adipose tissue cellularity and lipoprotein lipase (LPL) activity were estimated in 2- and 5-wk-old birds. In 2-wk-old birds, cellularity and LPL and glycerophosphate dehydrogenase (GPDH) activity were evaluated in the stromavascular fraction. At both ages studied, the fat line exhibited a twofold increase in mature fat cell number and a marked hypertrophy. LPL activity per cell did not differ with genotype, regardless of the nutritional state; however, LPL activity per whole fat pad was higher in fat birds. In 2-wk-old fat chickens, the stromavascular fraction was characterized by an increase in cell number and a decrease in LPL activity, while GPDH was unchanged. Finally, adipocyte hyperplasia in the fat line appeared to reflect an excessive proliferation of precursor cells. The higher LPL activity in fat birds resulted mainly from cell hyperplasia, rather than from a greater intrinsic activity of adipocytes. Consequently, enhanced fatty acid uptake by adipose tissue represents a major factor in determination of adiposity in the chicken.

Adipose Tissue↗
PubMed1989

Intramedullary epidermoid cyst evaluated by computed tomographic scan and magnetic resonance imaging: case report.

The authors have treated a 20-year-old man with a dorsal intramedullary epidermoid cyst in whom magnetic resonance imaging was performed both before evacuation of the cyst and 3 months later. Intraspinal epidermoid tumors are rare, and the intramedullary location is quite uncommon. To our knowledge, this is the first description of magnetic resonance imaging of an intramedullary epidermoid cyst. The frequency, possibilities, and limits of surgical treatment of such intraspinal benign tumors are reviewed.

Adult↗
PubMed1989

[Intracerebral graft of a line of chromaffin cells. Immunologic aspects and role of nerve growth factor in survival and differentiation of the graft].

The efficiency of neuronal grafts is correlated with the differentiation of the grafted cells and the connections they establish with the host tissue. The prolonged survival of a chromaffin cell line (PC12) transplanted into an immunodepressed rat brain shows that neuronal differentiation is correlated with the amount of nerve growth factor (N.G.F.) present in the grafted structure. This result is in agreement with in vitro studies. The characterization of other factors that influence the differentiation of PC12 cells in culture could lead to an increase in the efficiency of intracerebral grafts of adrenal medulla cells in Parkinson's disease.

Adrenal Gland Neoplasms↗
PubMed1989

[Spinal osteoid osteomas. Apropos of 4 cases].

Spinal osteoid osteomas constitute a rare but perfectly curable cause of non-disc root pain. In discussing four cases (2 cervical and 2 lumbar), the authors stress that this disorder affects above all males under 30 and presents as vertebral column pain gradually becoming radicular in character; the pain, essentially nocturnal, is spectacularly but transiently relieved by salicylates and is accompanied by often frank stiffness of the spine. The diagnosis is based less on X rays and tomographs, than on isotope bone scanning, which reveals a focus of intense hyperfixation, and CAT scanning which shows a bony lacuna possibly with an opacity in the center producing a rosette shaped image. Block excision of the osteoid osteoma produces immediate relief for the patient and prevents recurrence which only occurs exceptionally.

Adult↗
PubMed1988

Thyroid hormones in genetically lean or fat chickens: effects of age and triiodothyronine supplementation.

Thyroid hormones were measured in plasma of genetically lean (LL) or fat (FL) chickens at different ages. No differences were observed at hatching or at adult age. More triiodothyronine (T3) and less thyroxine (T4) were found in the plasma of LL than in FL at the fed state during the growth period. This difference disappeared as the birds approached sexual maturity. Dietary supplementation by T3 increased the plasma concentration of T3 at the fed state. It did not influence growth rate, feed efficiency and body temperature. T3 supplementation tended to decrease abdominal fat proportion. It is suggested that the difference in plasma T3 would account for only a small proportion of the between-genotype differences in fattening.

Aging↗
PubMed1986

Ligation of the CD23,p45 (BLAST-2,EBVCS) antigen triggers the cell-cycle progression of activated B lymphocytes.

CD23,p45 (BLAST-2,EBVCS) is a 45-kDa lineage-restricted antigen which appears on the surface of human B cells shortly after activation. A monoclonal antibody (MHM6) to CD23,p45, as well as a polyclonal rabbit antibody raised against the purified antigen were found to promote DNA synthesis in purified tonsillar B cells which had been activated with phorbol ester. Interleukin 1, which was not, by itself, stimulatory for either resting or activated B cells, significantly augmented the growth-promoting properties of MHM6. Kinetic studies indicated that while MHM6 exerted its influence in early G1, interleukin 1 acted later in the cycle just prior to the entry of cells into S phase. The findings demonstrate a role for CD23,p45 in triggering the progression of activated B lymphocytes through the G1 phase of the cell cycle. The possibility that this antigen serves as a receptor for a B cell stimulatory factor is discussed.

Animals↗
PubMed1986

Autocrine growth of human B lymphocytes: maintained response to autostimulatory factors is the special feature of immortalization by Epstein-Barr virus--a hypothesis.

The autocrine growth profile of human B lymphocytes transformed with Epstein-Barr virus (EBV) was found to comprise three distinct components: a B-cell growth factor (BCGF); an interleukin-1 (IL-1)-like activity; an activity requiring cell-to-cell contact for its action. Observations on the inhibition of the EBV-carrying Daudi lymphoma line by alpha-interferon indicated that loss of response to these autostimulatory factors was underlying growth cessation. Furthermore, a putative receptor for BCGF was found to be down-regulated on B cells stimulated with non-transforming mitogens but constitutively expressed following EBV-transformation. Taken together with recent evidence that normal B cells produce autostimulatory factors, these findings suggest that the special feature of autocrine growth by EBV-immortalized cells is a maintenance of what should normally be a transient phenotype, possibly through deregulation of receptor expression. This hypothesis is discussed.

B-Lymphocytes↗
PubMed1986

Control of human B-lymphocyte replication. I. Characterization of novel activation states that precede the entry of G0 B cells into cycle.

Tonsillar B lymphocytes of a particularly high buoyant density were prepared essentially free of contaminating monocytes and T cells. When exposed to anti-immunoglobulin, such cells initiated the hydrolysis of inositol phospholipids. This provides a postulated 'dual signal' for growth through the liberation of intracellular calcium stores and the activation of protein kinase C. Nevertheless, neither anti-immunoglobulin nor direct agonists of this bifurcating pathway (respectively, calcium ionophore and the phorbol ester TPA) were capable, when used alone, of driving cells out of G0 and into RNA synthesis. All three agents did, however, induce two activation antigens at the surface of G0 B cells, which included CD23, p45 and a lineage-unrestricted antigen identified by the monoclonal antibody BK.19.9. Cells that had been exposed to calcium ionophore, but not those activated with either TPA or anti-immunoglobulin, revealed further change indicated by an increased accessibility of their native DNA for the intercalating dye acridine orange. Cells receiving full mitogenic signals in the form of Staphylococcus aureus Cowan Strain I (SAC) or a combination of TPA and calcium ionophore showed the same initial sequelae but continued to enter the cell cycle and progress through to DNA synthesis. The observations identify two phases in the early activation of human B cells, both in terms of various temporal events, and the signals required to promote each activation state. before entering the proliferative cycle. Thus, the exit of human B cells from G0 appears subject to multiple controls that precede those associated with G1 and later phases of the cell cycle.

Antigens, Surface↗
PubMed1986

Control of human B-lymphocyte replication. II. Transforming Epstein-Barr virus exploits three distinct viral signals to undermine three separate control points in B-cell growth.

Highly purified resting (Go) B lymphocytes were monitored for their response to transforming Epstein-Barr virus (B95-8 strain), to a non-transforming mutant (P3HR-1) containing a deletion in the EBNA-2 coding region, and to inactivated virus of either type. All preparations induced an early appearance of two activation antigens, which included the CD23,p45 ("Blast-2') antigen. Thus, virus binding was sufficient for an initial activation step. Further change required an active viral genome. Infection with the P3HR-1 strain prompted the exit of cells out of Go but led to an arrest in the early G1 phase of the cycle. While initially showing sequels to activation indistinguishable from those observed with P3HR-1 virus, cells infected with B95-8 virus continued through G1 to express late activation antigens, enter S-phase and complete the replicative cycle. The addition of the phorbol ester TPA was found to compensate for the abortive cell cycle entry achieved with the P3HR-1 mutant, but could not supplement the minimal activation observed with inactivated virus. These findings demonstrate that the Epstein-Barr virus undermines three separate control points in the growth cycle of human B lymphocytes, and exploits three distinct viral signals to achieve this end.

Antigens, Viral↗
PubMed1986

Autocrine models of B-lymphocyte growth. II. Interleukin-1 supports the proliferation of transformed lymphoblasts but not the stimulation of resting B cells triggered through their receptors for antigen.

Purified, monocyte-derived interleukin-1 (IL-1) was found to provide growth support for Epstein-Barr virus (EBV) transformed B-lymphocytes seeded at densities below which their own autostimulatory factors were limiting. By contrast, highly purified resting B cells triggered via their receptors for antigen failed to respond to identical preparations of IL-1 by DNA synthesis. That successful priming of the B cells had occurred was evidenced by a transient rise in RNA synthesis and the ability of the cells to respond to T-cell supernatants by DNA synthesis. The findings indicate that while IL-1 might perform an autostimulatory function in B lymphocyte proliferation it is not by itself sufficient to provide growth support for resting B cells activated through their receptors for antigen. The implications of these observations for autocrine models of B-cell growth are discussed.

Antibodies, Anti-Idiotypic↗
PubMed1986

[Secondary hematoma of the brain stem. Apropos of 5 cases].

Five cases of brain-stem hematoma are described. The cause of these hematomas was identified as "cryptic angioma" (1 cavernous angioma, 1 telangiectasia, 3 arteriovenous malformations). So, they are so-called "secondary hematoma", as opposed to brain-stem hematoma in relation with hypertension. Such secondary hematomas are reported in the literature: 37 operated on cases and 22 untreated cases were found. The clinical picture does not seem to be typical. The presentation appears to be either with the acute onset of a stroke, or with a subacute onset including relapsing symptoms. A progressive deterioration suggesting a pontine glioma or mimicking demyelination is not rare. The CT scanner appearance is often characteristic showing a high density area in the brain-stem which enhanced after injection of contrast medium with an aspect of "halo". Angiography is usually negative. The natural history of brain-stem hematoma due to rupture of a cryptic angioma is not well documented, but it seems that prognosis is very poor. So, the authors insist on surgical evacuation which is effective and safe allowing the diagnosis of brain-stem hematoma and in some cases the identification of the malformation.

Adult↗
PubMed1985

alpha-Thalassemia hydrops fetalis: clinical and ultrasonographic considerations.

Five pregnant Southeast Asian women presenting during a 14-month period with microcytic anemia, preeclampsia, and size-date discrepancies were all ultimately diagnosed as carrying fetuses with homozygous alpha-thalassemia hydrops fetalis. The perinatal complications of this hemoglobin disorder are unique to persons of this ethnic background and include uniform fatality for the affected infant, maternal preeclamptic morbidity, and retained placenta. In this report the obstetric ultrasound findings are presented and the clinical manifestations are discussed, with recommendations made to reduce this emerging public health problem in the United States.

Adult↗
PubMed1985

A case of attempted suicide by self-hanging.

A young man arrived at the accident and emergency department after attempting suicidal self-hanging. He was cyanosed and showed severe respiratory distress. His posture, hyperreflexia and state of consciousness suggested decerebration. A dire prognosis was expected. Four days later he recovered. No residual physical or mental sequelae were found during follow up. The "post-suspension syndrome" in our case was similar to those recorded in several continental reviews. Apart from a case report of a "miraculous deliverance" following an unsuccessful judicial hanging at Oxford in 1650, no other report of this syndrome has been made in the English literature. This syndrome has an excellent prognosis and requires very little active intervention to ensure a favourable outcome.

Adult↗