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Biomedical subjects

A Haddad

Publications and source records attributed to A Haddad.

At least 145 records · Page 8Linked to original sources

Synthesis of lens capsule and plasma membrane glycoproteins by lens epithelial cells and fibers in the rat.

The lens of the eye possesses a capsule which is a greatly hypertrophied basement membrane. To investigate the synthesis of glycoproteins destined for this capsule, 3H-fucose was injected into the vitreous body of intact rats weighing approximately 200 gm. The animals were killed from 10 min to 14.5 months later, and their lenses were processed for electron microscope radioautography. At 10 min after injection, more than 58% of the silver grains were localized to the Golgi apparatus of the lens epithelial cells. By day 1, the heaviest sites of reaction were the plasma membrane (more than 50% of total label), the basal cytoplasm, and the adjacent lens capsule, where a heavy band of reaction was seen. The remainder of the capsule exhibited a lighter diffuse reaction. In the lens fibers, the label was at first localized to clusters of vesicles but then migrated to the plasma membrane and to the region of the capsule adjacent to the basal surface of these fibers. Light microscope radioautographs of the lens capsule at later time intervals revealed that by 1 month after injection the diffuse reaction had disappeared, and only the strongly labeled band remained. By 14.5 months after injection, this band had migrated partially across the lens capsule, but the capsule itself had increased considerably in thickness. On the other hand, the distance between the labeled band and the free edge of the capsule had decreased from that seen at the time of injection.

Animals↗

Histochemical and radioautographic study of glycoprotein secretion in the epithelium lining the uterine tubes of mice.

Two-month-old female Swiss mice that had come into estrus were injected intravenously with L-3H-fucose and killed at 5, 15, 40 min, and 4 h after injection. Pieces of the isthmus and of the ampulla of the uterine tubes were processed for light- and electron-microscopic radioautography. Incorporation of 3H-fucose was more intense in the isthmian secretory cells than in the ciliated cells of the ampulla. Electron-microscopic radioautography of the isthmian secretory cells demonstrated that 3H-fucose was incorporated into newly synthesized glycoproteins in the Golgi apparatus from where labelled glycoproteins migrated mainly to secretory granules and apical microvilli. The histochemical technique using ruthenium red confirmed the presence of glycoproteins in the contents of the secretory granules released to the lumen of the uterine tubes as demonstrated by radioautography. Other glycoproteins are transported inside small vesicles and most likely are related to the renewal of the plasma membrane. The role of the secretory glycoproteins in various events of mammalian reproduction is discussed.

Animals↗

[Influence of the distribution of collateral circulation on left ventricular segmental kinetics].

Correlations between left ventricular segmental kinetics and collateral circulation patterns were studied in 292 patients with coronary disease (182 women, 274 men: mean age 54 years). Left ventricular segmental kinetics were analyzed qualitatively by angiography (10 segments were individualized on RAO and LAO projections) and rated as normal, hypokinetic, akinetic or aneurysmal. The type of collateral circulation observed (contralateral, homocoronary and homolateral) and the number of collateral vessels were recorded. Collateral circulation was present in 49 p. 100 of the patients and in 29 p. 100 of the 587 pathological arteries (i.e. more than 50 p. 100 stenosis) identified. 89 p. 100 of the occluded arteries were revascularized by collateral circulation, the latter being effected by 213 collateral vessels (mean: 1.41 +/- 0.36 vessel per occluded artery). Collateral circulation through 1, 2 or 3 collateral vessels was noted in 62 p. 100, 35 p. 100 and 3 p. 100 respectively of the cases. Collateral circulation was contralateral in 51 p. 100, homocoronary in 33 p. 100 and homolateral in 16 p. 100 of the cases. Normal or hypokinetic segments in the territory of an occluded artery were more frequent in the presence (43 p. 100) than in the absence (31 p. 100) of collateral circulation, but the difference was not significant. They were also more frequent in three-vessel patients (59 p. 100) than in one-vessel (21 p. 100; p less than 0.01) or two-vessel (37 p. 100; p less than 0.05) patients in the presence of collateral circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Collateral Circulation↗

Synthesis and migration of 3H-fucose-labeled glycoproteins in the retinal pigment epithelium of albino rats, as visualized by radioautography.

3H-fucose was injected into the vitreous body of the eye(s) of 250-gm rats, which were then killed by means of an intracardiac perfusion with glutaraldehyde after intervals of 10 min, 1 and 4 hr, and 1 and 7 days. The eyes were removed and further fixed, and pieces of retina were processed for light and electron microscope radioautography. Light microscope radioautography showed that the pigment epithelial cells actively incorporated 3H-fucose label. The intensity of reaction peaked at 4 hr after injection of the label and then slowly declined. Quantitative electron microscope radioautography revealed that, at 10 min after 3H-fucose injection, over 70% of the label was localized to the Golgi apparatus, indicating that fucose residues are added to newly synthesized glycoproteins principally at this site. With time the proportion of label associated with the Golgi apparatus decreased, but that assigned to the infolded basal plasma membrane, the apical microvilli, and various apical lysosomes increased. These results indicate that in retinal pigment epithelial cells newly synthesized glycoproteins continuously migrate from the Golgi apparatus to lysosomes and to various regions of the plasma membrane. In this case, the membrane glycoproteins may play specific roles in receptor functions of the basal plasma membrane or phagocytic activities at the apical surface. Very little label migrated to Bruch's membrane, indicating either a very slow turnover or a paucity of fucose-containing glycoproteins at this site.

Animals↗

Radioautographic study of glycoprotein synthesis and fate in the hypothalamo-neurohypophyseal system of vasopressin-deficient Brattleboro rats.

L-3H-fucose was injected into the lateral cerebral ventricle of vasopressin-deficient Brattleboro and control Long-Evans rats which were subsequently killed at several time intervals after the injection. The hypothalamus and the neurohypophysis were processed for light- and electronmicroscopic radioautography. Other complementary experiments using immunocytochemical and enzyme-histochemical techniques were also undertaken. L-3H-fucose was incorporated into newly synthesized glycoproteins in the Golgi apparatus of supraoptic and paraventricular neurons, and later on labelled glycoproteins migrated to lysosomes and the plasma membrane surrounding the perikaryon. The Golgi apparatus of the vasopressin-deficient neurons remained heavily labelled as long as 3 days after injection, in sharp contrast with the normal neurons in which there was a remarkable decrease of label in the Golgi region between 4 and 24 h after the isotope administration. Labelled glycoproteins also migrated to the neurohypophysis and were mainly found in the axonal plasma membrane, vesicles and axoplasm. The renewal of glycoproteins in the neurohypophysis of Brattleboro rats was faster than in the normal rats and this was attributed to the lack of formation of products which are normally packaged in secretory granules in the perikaryon and released at the axon terminal in the neurohypophysis. Colchicine caused a disturbance in the topography of the organelles of the perikaryon and the most striking features were the displacement of Golgi stacks to the periphery of the perikaryon and an accumulation of mitochondria in this neuronal region. No secretory granules were observed in the vasopressin-deficient neurons of untreated or colchicine-treated Brattleboro rats. By contrast, secretory granules (most of them labelled with 3H-fucose) were concentrated in the perikaryon of colchicine-treated Long-Evans rats. In these rats, colchicine caused a severe block in the migration of 3H-fucose-labelled glycoproteins to the neurohypophysis, but this did not occur in the Brattleboro rats. The results of the experiments were interpreted in the light of the genetic defect known to occur in Brattleboro rats which causes the inability to produce vasopressin and also remarkable morphological and physiological changes in the affected neurons.

Acid Anhydride Hydrolases↗

CR3 receptor on platelets and its role in the prostaglandin metabolic pathway.

The human C3R receptor, which binds C3bi, present on the surface of monocytes, granulocytes and natural killer cells, can be detected by several monoclonal antibodies, OKM1, Mo1 and Mac-1 and also by RM2.184 which detects a polymorphism of the receptor. Platelets have been considered to lack complement receptors on their cell surface; however, we now describe the detection of CR3 receptors on human platelets by radioimmunoassay using both OKM1 and RM2.184 antibodies. Using OKM1, immunoprecipitation studies with 125I-labelled platelets revealed the typical CR3 complex with an alpha chain of 165,000 daltons and beta chain of 95,000 daltons. By immunofluorescence, megakaryocytes were also found to be OKM1+. However, platelet CR3 does not merely bind C3bi, but the binding of the OKM1 antibody to platelet CR3 selectively blocks platelet functions of aggregation and serotonin release induced by arachadonic acid but not by other ligands (ristocetin, ADP, L-epinephrine, collagen and thrombin). The studies demonstrate an important role of platelet CR3 in both complement binding and in prostaglandin metabolic pathways.

Antibodies, Monoclonal↗

Localization of glycoproteins in insulin secretory granules by ultrastructural autoradiography.

To determine whether or not the secretory granules of insulin-secreting cells contained glycoproteins, isolated rat pancreatic islets were incubated for 2 and 4 hr in a medium containing L-[3H]-fucose. Quantitative analysis of high-resolution electron microscopic autoradiographs of the insulin-secreting beta cells demonstrated that glycoproteins with fucose residues are contained within the insulin secretory granule.

Animals↗

Autoradiographic demonstration of in vivo sialylation of endogenous acceptors at the microvillar surface of intestinal columnar cells after intraluminal administration of CMP-[3H]-sialic acid.

To investigate the presence of glycosyltransferase activity at the apical surfaces of columnar cells in small intestine, CMP-[3H]-sialic acid was injected into the lumen of a ligated segment of rat jejunum; 5 min later the tissue was fixed and processed for light microscopic autoradiography. After a 3-6-month exposure, an autoradiographic reaction appeared over the microvillar surfaces of columnar cells, indicating the presence of surface sialyltransferase activity accompanied by endogenous acceptors. When CMP-[3H]-sialic acid was injected into the posterior chamber of rat eye or the lumen of mouse gallbladder, no autoradiographic reaction was observed at the surfaces of the cells facing these cavities. After injection of UDP-[3H]-galactose into the same three sites, an autoradiographic reaction was observed in the Golgi regions of the various epithelial cells, but not along their apical surfaces. Competition experiments using unlabeled galactose indicated that [3H]-galactose had been released from the nucleotide and had entered the cells to be incorporated into the Golgi apparatus.

Animals↗

Kidney immunopathology and pathophysiology in rats immunized with proximal tubule cell brush border or basolateral membrane vesicles.

Proximal tubule pathology in Heymann nephritis has been attributed to anti-brush border antibodies, but antibodies with other specificities might also be important. To determine whether injury to the basolateral membranes of proximal tubules could occur independently of brush border injury, LEW rats were immunized either with partially purified basolateral or brush border membrane vesicles. Both immunogens produced glomerular immunopathology and pathophysiology identical in magnitude and time course to that seen in Heymann nephritis. Antibodies eluted from the kidneys of rats immunized with either antigen preparation stained the brush border in vitro. However, circulating anti-brush border antibodies were in significant titers only in rats immunized with brush border vesicles, whereas antibodies that stained the cytoplasm of both proximal and distal tubules predominated in rats immunized with basolateral membranes. With the onset of proteinuria, rats immunized with brush border membranes developed the proximal tubule pathology of Heymann nephritis. In rats immunized with basolateral membranes, the brush border and apical aspect of proximal tubule cells remained essentially normal. However, defects of basolateral membrane transport function were present, indicating that those defects need not necessarily be secondary to brush border damage. The dissociation of brush border damage from glomerular injury suggests that different antibody populations may account for each. Furthermore, anti-brush border antibodies may not account for all aspects of proximal tubule pathology in Heymann nephritis.

Animals↗

[Myocardial metabolism in angina with angiographically normal coronary arteries].

Myocardial metabolism was studied during rapid atrial pacing in 22 patients with angina and angiographically normal coronary arteries. Pyruvate, non esterified fatty acid and lactate levels were measured in the coronary arteries and veins under basal conditions, at the peak of atrial pacing and during the recovery phase. A control group of 8 patients had neither angina, ST depression, or lactate production during atrial pacing. A correlation was observed between the coronary arterio-venous difference and arterial pyruvate and non esterified fatty acid levels in the 22 patients during the 3 periods of study. The control patients did not differ significantly from the rest of the population. There was a correlation between the coronary arterio-venous difference and arterial lactate levels under basal conditions in all of the study and control groups. This correlation remained significant during atrial pacing and the recovery period only in the control group. It was possible to distinguish a group of 14 patients (64 p. 100) (Group A) with a correlation coefficient of lactate production similar to the control group (+/- 2 standard deviations) during atrial pacing, from a second group of 8 patients (36 p. 100) (Group B) with abnormal myocardial metabolism. The arterial lactate concentrations were similar in both groups in the 3 periods of study. A coefficient of lactate extraction less than 10 p. 100 was observed in 2 patients in Group A and in 7 patients in Group B (88 p. 100, p less than 0.01). One patient in Group B had a coefficient of lactate extraction greater than 10 p. 100 (+ 13 p. 100).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Synthesis and migration of 3H-fucose-labeled glycoproteins in the ciliary epithelium of the eye: effects of microtubule-disrupting drugs.

3H-fucose was injected intravenously or intravitreously into albino rats. After time intervals of 10, 40, and 50 min, 1, 1.5, and 4 hr, 1, 3, and 7 days, and 1, 2, and 4 weeks after injection, the animals were sacrificed by intracardiac perfusion with glutaraldehyde. Samples of the ciliary body were prepared for light and electron microscope radioautography. Light microscope autoradiographs showed that the cells of both the inner and outer layers of ciliary epithelium actively incorporated 3H-fucose label in a reaction that peaked in intensity at 4 hr after injection, and then progressively declined. Electron microscope radioautographs revealed that, at early time intervals, most of the label was localized to the Golgi apparatus. With time, the plasma membrane of both cell types became increasingly labeled, and accounted for 60-70% of the total silver grains at 4 hr after injection. Adjacent to the basal cell surface of the inner layer cells, the fibers of the zonula became increasingly labeled from 1.5 hr onwards, providing strong evidence that these cells secrete glycoproteins to the zonula. When vinblastine was administered 30 min before 3H-fucose injection, followed by sacrifice 1.5 hr later, a much larger proportion of label remained localized to the Golgi apparatus than in controls, and the plasma membrane and zonula were much less labeled. These results suggest that, as documented in other cell types, microtubules may play a role in the intracellular transport of membrane and secretory glycoproteins in these cells.

Animals↗

Chenodeoxycholic and ursodeoxycholic acids alter motility and fluid transit in the canine ileum.

We examined the effects of chenodeoxycholic acid (CDCA) and ursodeoxycholic acid (UDCA) on fasting motility patterns and transit in ileocolonic loops of 5 dogs. Animals were prepared with isolated loops (40 cm ileum and 5 cm colon) which maintained neuromuscular continuity with the intact bowel through a bridge of tunica muscularis. Myoelectrical activity was recorded from multiple serosal, monopolar electrodes and muscle contractions recorded from serosal strain gauges; fluid transit was assessed by continuous perfusion (1.4 ml min-1) of solutions containing polyethylene glycol 4000 marker, with or without bile acids. Saline perfusion did not disturb the fasting cycle of motility and mean cycle length in unperfused (106 +/- 7 min) loop was the same as during perfusion of saline (108 +/- 9 min). Bile acids abolished interdigestive cycles in 11 of 12 experiments, fasting patterns returned 64-106 min after bile acid perfusion was stopped. The fasting pattern continued to cycle normally in the proximal small bowel during bile acid perfusion. CDCA (15 mM) stimulated the occurrence of propulsive contractions of long duration. Bile acids shortened transit time through the loops and altered the pattern of flow towards a more continuous, steady stream. These effects of bile acids on ileal motility, like those described previously in the colon, could play a role in bile acid diarrhea.

Animals↗

Management of the undescended thyroid.

Ectopic thyroid can occur throughout the neck but is found most commonly at the tongue base. Management includes Tc99m radionuclide scanning to confirm the presence and location of the thyroid tissue. Dysfunction should be assessed by T4, TSH, and thyroid antibody testing. Hormonal therapy is the primary treatment but surgery may be necessary in cases of airway obstruction. Six children with undescended thyroid are presented and a management protocol based on the presence or lack of symptomatology is proposed.

Child↗

Effects of morphine and atropine on motility and transit in the human ileum.

We examined motility of the ileocecal region, pressures at the ileocecal sphincter, and ileal flow after therapeutic doses of morphine and atropine. Using a factorial design in two cells of 8 (2(3] subjects, drugs were given during fasting and postcibally. Morphine (100 micrograms/kg body wt as a bolus intravenously) and atropine (7 micrograms/kg body wt as a bolus) stimulated migrating bursts of phasic activity (similar to phase III of the migrating motor complex). Morphine initially stimulated ileal flow, but atropine could not be shown to have this effect. Atropine reduced markedly the occurrence of sporadic pressure waves in the ileum, but morphine did not. Whereas atropine delayed mouth-to-ileum transit of polyethylene glycol, given in a mixed meal, morphine did not. Naloxone, in the dosage used (40 micrograms/kg body wt as a bolus, followed by 10 micrograms/kg body wt X h) had no independent effects on motility or flow, but did blunt the stimulatory effects of morphine and atropine on migrating motor complexes. We could not demonstrate an effect of any drug on the transit of lactulose from terminal ileum to cecum. Neither morphine nor atropine had impressive effects on tone at the ileocecal sphincter. These observations, while not specifying the mechanisms for constipation after opiates or anticholinergics, highlight the complexities of small bowel transit in humans and point out that the antidiarrheal effects of drugs are probably multifactorial.

Adult↗