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Biomedical subjects

S Gross

Publications and source records attributed to S Gross.

At least 109 records · Page 6Linked to original sources
PubMed1994

[Lumbar intervertebral disk. Structure. Knowledge status].

The purpose of this paper is to review the main data on the structure of the intervertebral disc, which are illustrated by personal documents. Applications in understanding the degenerative pathology are highlighted. The nucleus pulposus is the "central" component of the disc, highly hydrophilic, deformable but remaining of constant volume. It can be compared to a hydraulic chamber within the disc, sealed by the annulus fibrosus, which is a dense peripheric ring of concentric fibrous lamellae. The cartilaginous end plates (cranial and caudal) separate the disc from the adjacent subchondral vertebral bone. (Their involvement in the discal metabolism as well as the blood supply of the disc are developed elsewhere (see our companion article)).

Cartilage↗
PubMed1994

[Lumbar intervertebral disk. Intervertebral disk-vertebral body pathways and discal vascularization].

We studied the disco-vertebral interface and the blood supply of the intervertebral disks L3-L4, L4-L5, and L5-S1 of 5 human adult columns. Moreover, in order to investigate the discal vasculature, infusion of Japanese ink was used in 2 other adult columns, as well as immuno-histological methods in the L5-S1 disk of 4 adults and 2 infants. Our study confirms the paucity of discal vasculature in adults, by contrast with that of infants, but shows numerous defects in the subchondral vertebral plate, which are filled by vascularised medullary soft tissue and are in contact with the cartilaginous discal end plate. By these contacts, nutrients could reach the intervertebral disk, as suggested by other works, and as is the case in other cartilaginous structures of the body.

Humans↗
PubMed1994

Treatment of recurrent suprahyoid cervicofacial lymphangioma with intravenous cyclophosphamide.

PURPOSE: Surgical resection of cervicofacial cystic hygromas and lymphangiomas rarely effects complete reduction because of severe anatomic restrictions. PATIENTS AND METHODS: With prior knowledge of cyclophosphamide activity against lesions of this type, a formal trial of cyclophosphamide was initiated. RESULTS: Overall dose escalation therapy resulted in 50% reduction in mass without recurrence after cessation of therapy and with minimal and readily reversible toxicity. CONCLUSIONS: The favorable responses to cyclophosphamide in this study suggest that a prospective randomized trial should be initiated. Certainly, children who have airway and/or esophageal compromise who have failed surgical therapies should be considered for cyclophosphamide treatment.

Child↗
PubMed1993

Codeine disposition in sickle cell patients compared with healthy volunteers.

The pharmacokinetics of codeine were determined after oral administration of codeine sulfate (60 mg) with sickle cell patients (SCPs) and healthy controls (HCs). Plasma concentrations of codeine were measured by reversed-phase high-pressure liquid chromatography with fluorescence detection. Pharmacokinetic parameters were calculated using both compartmental and noncompartmental analysis. No significant differences were observed in time to reach maximum peak plasma concentration (tmax) (1.0 +/- 0.4 versus 1.4 +/- 1.0 hours), maximum peak plasma concentration (Cmax) (172 +/- 25 versus 225 +/- 97 ng/mL), area under the curve (AUC infinity) (590 +/- 96 versus 779 +/- 234 ng*h/mL), and Cl/F (104 +/- 17 versus 89 +/- 27 L/h) between SCPs and HCs. Conversely, significant differences were observed in mean residence time (MRT) (3.7 +/- 0.3 versus 4.7 +/- 0.3 hours) and half-life (t1/2) (1.7 +/- 0.2 versus 2.8 +/- 0.3 hours). In a separate study, significant differences were observed in the in vitro plasma protein binding of codeine in SCPs (66.0 +/- 8.6%) and HCs (30.5 +/- 2.7%) as well as in vivo binding (68.4 +/- 11.1% for SCPs versus 29.2 +/- 3.4% for HCs). Codeine is a relatively high-extraction drug that is primarily eliminated by metabolism in the liver. Generally, the clearance of such drugs is approximately equal to hepatic blood flow and is not affected by changes in protein binding. Therefore, the change in t1/2 observed in SCPs can be attributed to changes in volume of distribution rather than clearance.

Adult↗
PubMed1993

Increased erythrocyte and protein binding of codeine in patients with sickle cell disease.

Erythrocyte binding and plasma protein binding of codeine in sickle cell patients and healthy controls were determined. A reversed-phase HPLC procedure was used for codeine analysis. Codeine was extracted from alkalinized plasma, separated on a CN column, and assayed by fluorescence detection. The erythrocyte-buffer partition coefficient was significantly higher in sickle cell patients (1.72 +/- 0.21) than in healthy controls (1.25 +/- 0.14). No time dependence of partitioning was observed. The fraction of codeine bound to plasma proteins, determined by ultrafiltration, was significantly higher in sickle cell patients (66.0% +/- 8.6%) than in healthy controls (30.5% +/- 2.7%). No concentration dependence of erythrocyte or protein binding was observed. Further studies were performed to elucidate the binding mechanisms. From a ghost cell binding study it was concluded that the major binding sites for codeine are in the cell membrane. A decrease in codeine binding was observed in the presence of bilirubin. Codeine binding to alpha 1-acid glycoprotein was found to be minimal. The levels of alpha 1-acid glycoprotein and other glycoproteins in sickle cell patients and healthy controls were measured by glycoprotein electrophoresis. The results showed no significant difference between the two groups. Plasma protein electrophoresis was performed for the two groups. The results showed a significant difference in gamma-globulin levels between sickle cell patients and healthy controls. Codeine is known to bind to gamma-globulin, a fact that may explain in part the observed increase in the plasma protein binding of codeine in sickle cell patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia, Sickle Cell↗
PubMed1993

Molecular definition of the Prader-Willi syndrome chromosome region and orientation of the SNRPN gene.

The Prader-Willi syndrome and the Angelman syndrome are caused by the loss of function of distinct but closely linked genes on human chromosome 15. Based on a yeast artificial chromosome restriction map and two key patients we have determined that the shortest region of deletion overlap in the Prader-Willi syndrome comprises 320 kb. The region includes the anonymous DNA marker PW71 (D15S63) and the gene for the small nuclear ribonucleoprotein N (SNRPN). The SNRPN gene maps 130 kb distal to PW71 and is transcribed from centromere to telomere.

Autoantigens↗
PubMed1993

Characterization of a methylation imprint in the Prader-Willi syndrome chromosome region.

In adult human tissues, a HpaII and a CfoI restriction site at the PW71 (D15S63) locus in the Prader-Willi syndrome region on chromosome 15 are methylated on the maternal chromosome, but unmethylated on the paternal chromosome. The HpaII site is part of a sequence with high homology to the long terminal repeat of human endogenous retroviruses. Another HpaII site at the PW71 locus is methylated on both chromosomes. Sperm DNA carries the adult paternal methylation pattern. Oocyte DNA could not be studied. In chorion, placenta and tumor DNA, both HpaII sites are unmethylated. These findings suggest that the PW71 methylation imprint is established in the germline and that extraembryonic tissues and tumors are hypomethylated.

Adult↗
PubMed1993

The use of computers in teaching clinical laboratory science.

The Transfusion Medicine Tutor (TMT) has been designed to study the use of computers in teaching concepts and problem- solving skills important in the field of clinical laboratory science. This system provides students with an opportunity to gain experience by solving a wide range of actual cases, and coaches these students when they are having difficulties. This system is designed specifically to detect and respond to a variety of errors that students may make while solving cases, and to suggest more advanced problem-solving methods when appropriate. This article describes the concepts behind the design of TMT.

Journal Article↗
PubMed1993

Estrogen blocks the cimetidine-induced suppression of CFU-GM.

Cimetidine, an H2-histamine antagonist used for the treatment of duodenal ulcers, has been shown to suppress granulocyte/macrophage colony forming cells (CFU-GM) in males. This study was initiated to examine the role of sex hormones on this cimetidine-induced suppression of CFU-GM. Preincubation of light-density, nonadherent bone marrow cells in male patients with 10(-6) M testosterone resulted in a modest decrease in the suppressive effect of cimetidine, whereas preincubation with 10(-6) M 17-beta-estradiol, for as little as 10 minutes, completely abolished the 50% reduction in colony numbers induced by cimetidine. Using supra-pharmacologic doses of cimetidine in order to detect CFU-GM suppression in female patients, identical results were obtained. Tamoxifen completely reversed this protective effect of estrogen and preincubation with hydroxyurea and the elimination of T cells from the system failed to alter any of these results, lending support to the likelihood that both cimetidine and estrogen directly affect marrow myeloid progenitor cells.

Cell Division↗
PubMed1992

Evaluation of the iron chelation potential of hydrazones of pyridoxal, salicylaldehyde and 2-hydroxy-1-naphthylaldehyde using the hepatocyte in culture.

A range of new analogues of the promising iron chelator pyridoxal isonicotinoyl hydrazone was prepared and assessed for activity in reducing hepatocyte iron, mechanism of action and potential in iron-chelation therapy. A total of 45 compounds were synthesized by condensation of aromatic aldehydes (pyridoxal, salicylaldehyde and 2-hydroxy-1-naphthylaldehyde) with various acid hydrazides prepared by systematic substitutions on the benzene ring or by the replacement of the ring with an acetyl, pyridyl, furoyl or thiophene moiety. The effects of these compounds on 59Fe uptake and intracellular distribution in hepatocytes in culture and on 59Fe mobilization from prelabeled hepatocytes were assessed. Toxicity, lipophilicity and the ability to chelate plasma transferrin-bound 59Fe were also evaluated. Several compounds were much more active than pyridoxal isonicotinoyl hydrazone and may have clinical potential. These included pyridoxal benzoyl hydrazone, pyridoxal p-methoxybenzoyl hydrazone, pyridoxal m-fluorobenzoyl hydrazone and pyridoxal 2-pyridyl hydrazone. All were more effective at reducing iron uptake than mobilizing hepatocyte iron; they also may act primarily on the transit iron pool rather than on storage iron. Other compounds (e.g., salicylaldehyde p-t-butyl-benzoyl hydrazone) redistributed ferritin-59Fe to different intracellular sites but had little net effect on hepatocyte iron levels.

Animals↗
PubMed1992

Role of immunoglobulin subclasses and specific antibody determinations in the evaluation of recurrent infection in children.

We studied humoral immune function in 267 children with recurrent respiratory infections referred to our immunology clinic to determine the most appropriate immunologic studies for evaluating recurrent infections in children. Of this highly selected population, 58% had a partial deficiency in one or more of the major immunoglobulin isotypes or IgG subclasses (defined as at least 2 SD below the normal age-adjusted mean). In none of the patients was there a total absence of an immunoglobulin isotype. The most common abnormality was partial IgA deficiency, which was found in one third of the patients. Twenty-six patients had only partial IgG subclass deficiencies, of which 20 were deficiencies of a single subclass. IgG1 was an isolated partial defect in three patients, IgG3 in five patients, and IgG2 and IgG4 were selective partial defects in six patients each. Tetanus toxoid and pneumopolysaccharide type 3 were the most immunogenic of the immunogens tested; hyporesponsiveness to pneumococcal polysaccharide types 7, 9, and 14 was common. Nineteen percent of the patients with normal immunoglobulin concentrations who were tested had lower-than-expected antibody titers; 42% of those tested with partial isotype deficiencies had deficient antibody responses. Of 25 patients with selective partial IgG subclass deficiencies or combined IgG subclass deficiencies, eight had antibody deficiencies. Our findings indicate that a high proportion of children referred to immunology clinics for recurrent infection have a demonstrable immunologic abnormality. Selective IgG subclass deficiency or a combined IgG subclass deficiency without an associated deficiency in a major immunoglobulin isotype is unusual. Identification of such patients is not predictive of the capacity to form antibodies to the antigens tested in this study and, in our opinion, adds little to the initial evaluation of immune function in such children.

Adolescent↗