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Biomedical subjects

G Stelzer

Publications and source records attributed to G Stelzer.

34 records · Page 2Linked to original sources
PubMed1994

Induction of immature thymocyte proliferation after castration of normal male mice.

The physiological basis and immunological significance of thymic enlargement in castrate male animals is not known. We used normal male C57 Bl/6 mice to examine the contribution of in situ thymocyte proliferation to castration-induced enlargement of the thymus. Animals castrated at 8-10 weeks of age were compared to normal intact males. Thymocytes were examined 4-120 days after castration using flow cytometry to determine DNA content and thus the number of cells in active phases of the cell cycle. These properties were examined in unseparated thymocytes and in phenotypic subpopulations defined by expression of CD3, CD4, and CD8. For thymocytes obtained from intact control glands, a mean of 11.0 +/- 1.0% were in active phases of the cell cycle. The percentage of cycling thymocytes was increased to a mean of 22.5 +/- 1.9% in the week after castration (P < 0.001). This change occurred in the absence of significant thymic enlargement. At 8-10 days after castration, thymic weight increased abruptly to a new steady state which was double that of intact controls (78.0 +/- 4.1 vs. 39.1 +/- 2.6 mg; P < 0.001). In these enlarged glands, only 9.9 +/- 0.8% of cells were cycling, which was not significantly different than controls (P > 0.3). Proliferating cells identified in fixed thymus tissue sections after in vivo administration of bromodeoxyuridine were located in the subcapsular cortex and medulla. Analyses of thymocyte subpopulations indicated that most cycling cells had immature phenotypes (CD4+CD8+, CD4-CD8+, and CD3lo or CD3-). Castrate glands studied in the steady state period 8-120 days after surgery contained significantly fewer CD3+ cells than intact controls (P < or = 0.045). The findings suggest an intrathymic role for androgens in affecting generation of the mature T cell repertoire.

Animals↗
PubMed1993

Interleukin involvement in anterior pituitary cell growth regulation: effects of IL-2 and IL-6.

The pituitary gland plays a central role in the interactions between the immune and neuroendocrine systems. The expression of receptors for interleukin-1 (IL-1), IL-2, and IL-6 and the intrinsic production of these ILs by pituitary cells have been described. Previous studies have focused on the way cytokines influence hormone secretion. We have determined whether, in addition to these effects, ILs could affect pituitary cell proliferation. In GH3 cells, both IL-2 (1-100 U/ml) and IL-6 (10-500 U/ml) significantly stimulated [3H]thymidine incorporation and cell count. In contrast, inhibitory effects of both IL-2 and IL-6 at the same concentrations were observed on normal rat anterior pituitary cell growth. This finding was clearly evident when cells were cultured in Minimum Essential Medium-D-valine medium, a condition that results in cultures virtually free of fibroblasts. Autoradiographic studies confirmed that [3H]thymidine was only incorporated in the nucleus of nonfibroblastic pituitary cells. No direct correlation between the effects of IL-2 and IL-6 on cell growth and hormone secretion was apparent. By immunofluorescence, we observed IL-2 receptor expression on GH3 cells and, for the normal rat cultures, a high percentage of PRL-secreting and a lower percentage of GH-producing cells expressing IL-2 receptors, providing new evidence for a direct site of action of IL-2 on pituitary cells. Considering that uncontrolled division of cells may result from either excessive growth stimulation or deficient growth inhibition, the regulation of pituitary cell growth by IL-2 and IL-6 together with their intrinsic pituitary production could be of potential importance in pituitary adenoma pathogenesis.

Animals↗
PubMed1992

Two cellular single-strand-specific DNA-binding proteins interact with two regions of the bovine papillomavirus type 1 genome, including the origin of DNA replication.

We have identified and purified to near homogeneity two specific single-stranded DNA-binding factors (SPSF I and II) with molecular masses of 42 and 39 kDa, respectively, from calf thymus. Gel retention analysis and competition experiments demonstrate that the ubiquitous proteins SPSF I and II specifically interact with single-stranded DNA derived from the minimal in vitro origin of replication of bovine papillomavirus type 1 and a region of the viral genome proposed to be involved in plasmid maintenance. Bovine papillomavirus type 1 proteins do not interfere with DNA binding of SPSF I and II. The exact location of the binding domains of SPSF I and II on the DNA has been determined by methylation interference and T4 DNA polymerase footprinting. A potential cellular binding site for SPSF I and II is the major promoter (P2) of the human c-myc gene.

3T3 Cells↗
PubMed1992

Interleukin-2 and interleukin-2 receptor expression in human corticotrophic adenoma and murine pituitary cell cultures.

The production of IL-1 and IL-6 by pituitary cells has recently been demonstrated. In this study we investigated the expression of IL-2 and its receptor (IL-2R) by pituitary cells of different species. In Northern blots, a single hybridizing band of 1 kb, identical to that in normal stimulated lymphocytes, was obtained with specific IL-2 probes. In the mouse AT-20 pituitary tumor cell line, IL-2 mRNA expression was detected after stimulation with corticotropin-releasing hormone or phorbol myristate acetate. In human corticotrophic adenoma cells, basal IL-2 mRNA expression as well as IL-2 secretion were further stimulated by phorbol myristate acetate. Both adenoma and AtT-20 cells showed detectable amounts of IL-2R mRNA and by immunofluorescence, IL-2R membrane expression. In addition, dual immunofluorescence studies in rat anterior pituitary cells demonstrated colocalization of IL-2R with ACTH-positive cells and other cell types expressing the receptor. In addition to the action of lymphocyte-produced IL-2, this cytokine may have a paracrine or autocrine regulatory role within the pituitary. It remains to be established whether IL-2 production occurs in the normal pituitary or is intrinsic to the process of tumor development of these cells. IL-2 may be involved in the growth control of pituitary cells.

Adenoma↗
PubMed1988

Isolation and characterization of the porcine nuclear factor I (NFI) gene.

This study describes the isolation of a major portion of the gene for nuclear factor I (NFI) including its 5'-flanking region with transcriptional start sites. We screened a porcine liver, genomic DNA library in phage EMBL3A with synthetic oligonucleotides derived from tryptic and cyanogen-bromide peptide sequences obtained from purified NFI protein. The NFI gene is present as a single copy in porcine DNA.

Amino Acid Sequence↗
PubMed1987

Flow estimation by DSA in bypasses with or without a distal arterio-venous fistula.

Flow of contrast medium in bypasses with or without an arteriovenous fistula (AVF) has been measured using a densitometric technique. Modern digital subtraction angiography (DSA) equipment has the ability to produce images related to the density of the bolus of contrast passing down the vessel and to measure flow from them. Three studies were performed; (1) the method was tested in a model where it was compared with direct flow measurement; (2) A flow study was carried out in four groups of different below knee bypasses; (3) A study to examine the distribution of flow in adjunctive arteriovenous fistula was performed. The first study showed that the method was reliable and highly reproducible; the mean relative variance of DSA measured flow to the real flow being 3.05% and never more than 10%. The second study showed mean flow for various bypasses as shown below: (1) 10 fem.pop. bypasses (61-202 ml/min). 120 ml/min; (2) 10 fem.tib. bypasses (41-190 ml/min). 120 ml/min; (3) 10 fem.tib. bypasses with AVF(243-455 ml/min). 321 ml/min; (4) 10 pop.pedal. bypasses with AVF(112-382 ml/min). 261 ml/min. The differences between group 1 and 2 and group 3 and 4 are significant (P less than 0.005). The third study showed that relatively little of the blood entering an AVF passes distally into the arterial bed (Mean: 11%, 6-19%). In conclusion, DSA flow measurement is a reliable method of flow measurement. An AVF increases graft flow 2-3 times but only about 10% of the blood passes distally into the arterial system.

Anastomosis, Surgical↗
PubMed1987

Pedal and distal lower leg bypasses with a distal arteriovenous fistula.

In forty patients 41 feet were revascularised by means of distal tibial (the distal 10 cm of the lower leg) (17) or pedal bypasses (24). Angiographically the preoperative state was best defined as a lower leg block (LLB); All three arteries showing occlusions at several levels, leaving only isolated functioning arterial segments in the distal leg or foot with relatively good femoral and popliteal arteries. As might be expected this condition was mainly found in diabetics (75%). Only feet with severe rest pain (4) or rest pain with gangrene (37) were operated upon. To improve the distal outflow a side-to-side arteriovenous fistula (AVF) was added to the distal anastomosis. With a mean follow-up of 21 months (1-40 months) the limb salvage rate was 79% and the patency rate 67%. Special problems were experienced with cellulitis of the foot, causing the loss of three feet despite an open bypass and sufficient revascularisation. Furthermore, occlusion of the bypass after healing of the lesion did not necessarily mean a recurrence of gangrene. As this series shows, even in angiographically apparently hopeless cases, a bypass to the foot can prevent an otherwise unavoidable amputation.

Aged↗
PubMed1987

Subacute cutaneous lupus erythematosus in multiple members of a family with C2 deficiency.

Deficiency of the second component of complement (C2d) has been associated with systemic lupus erythematosus (LE)-like syndromes as well as recurrent infections. In particular, C2d has been associated with the LE subset of subacute cutaneous LE (SCLE), the presence of anti-Ro antibodies (anti-Ro or SS-A), and the human leukocyte antigen (HLA) types A25, B18, and DR2. A family with C2d in which three members have developed SCLE was observed and studied clinically, serologically, and immunogenetically. Deficiency of the second component of complement was present in all six family members, while anti-Ro was present in only two. There was a strong but incomplete association of C2d and SCLE with HLA-DR2, but the association was not complete with positivity of anti-Ro or antinuclear antibodies. Study of this family reconfirmed the close association of HLA-A25, -B18 and -DR2 with the C2 gene, but indicated a less close association of these loci with serologic markers.

Adult↗
PubMed1986

Subacute cutaneous lupus erythematosus. Clinical, serologic, and immunogenetic studies of forty-nine patients seen in a nonreferral setting.

Subacute cutaneous lupus erythematosus has been clearly recognized as a distinct cutaneous manifestation of lupus erythematosus. Two forms have been described, an annular erythema and a papulosquamous variant. Previous data have suggested that these patients have a high incidence of mild to moderate systemic disease, anti-Ro (SS-A) antibodies, and human lymphocyte antigen (HLA)-DR3, particularly the annular form. We studied forty-nine patients with subacute cutaneous lupus erythematosus seen in local private practices in our area. Lesions of chronic cutaneous lupus erythematosus were seen in 34.8% of our patients. Twenty-five patients (51%) fulfilled the American Rheumatism Association criteria for the classification of systemic lupus erythematosus, and renal disease was present in nine of these patients (including 3 with decreased function). Antibodies to Ro (SS-A) and/or La (SS-B) were present in only sixteen patients, and HLA-DR3 was found in only seventeen patients. Twenty-two patients had inactive cutaneous disease at follow-up. We concluded that our patient population with subacute cutaneous lupus erythematosus skin lesions is less distinctive than previous literature suggests. The serologic and immunogenetic correlates were not demonstrated. The full range of lupus erythematosus-related disease was seen, although most patients follow a benign course.

Acute Disease↗
PubMed1985

Neonatal lupus erythematosus occurring in one fraternal twin. Serologic and immunogenetic studies.

Neonatal lupus erythematosus (LE) is a syndrome that is manifested by LE skin lesions and/or congenital heart block, occurring in infants at, or shortly after, birth. The syndrome is believed to be caused by transplacental passage of an IgG antibody, usually the anti-Ro (SS-A) antibody, from the mother to the infant. Although the mother may have a connective tissue disease or may be healthy, the common characteristic is the presence of maternal circulating anti-Ro antibody. It has been believed that the HLA determinants demonstrated in children who have neonatal LE were not a factor in the expression of the syndrome. We report the occurrence of neonatal LE, manifested by photosensitivity and discoid LE skin lesions, in one fraternal twin. HLA studies of this affected twin demonstrated the presence of DR3. Anti-Ro antibody was present in the mother, but was not present in either child at 4 months post-delivery. HLA determinants may be involved in the expression of disease in neonates who have been exposed to the anti-Ro antibody. Furthermore, the presence of circulating antibodies in the unaffected twin causes us to question the assumption that the anti-Ro antibody is the causative factor for the occurrence of tissue injury in children with neonatal LE.

Adult↗
PubMed1984

Monoclonal antibody analysis of responder and stimulator cells in the human autologous mixed lymphocyte reaction.

Responder and stimulator cell subpopulations in the autologous mixed lymphocyte reaction (AMLR) were determined with the OK series of monoclonal antibodies. Mitomycin-C-treated, monocyte-enriched cell populations were used as stimulator cells in the AMLR. Treatment of these monocytes with either OKM and/or OKI monoclonal antibodies and complement resulted in a marked loss of ability of these cells to act as stimulators in the AMLR. Removal of OKT3+ and OKT4+ cells diminished the proliferative responses of AMLR cultures. Interaction of T cells with autologous monocytes resulted in generation of cells capable of suppressing both MLR and AMLR cultures. The suppressor activity of these cells was diminished by treatment with OKI , OKT4 or OKT8 monoclonal antibodies. No cytotoxic activity to autologous or allogeneic monocytes was observed. Additional studies showed an increased number of OKT9 + and OKI + as well as OKT8+ T cells in the AMLR responder cell population. This study indicates that cultures of T lymphocytes with autologous monocytes yield T cell subset(s) which suppress MLR and AMLR reactivity.

Antibodies, Monoclonal↗