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H Burger

Publications and source records attributed to H Burger.

At least 145 records · Page 8Linked to original sources
PubMed1994

Identification of functional domains of interleukin-3 by construction of primate interspecies chimera.

Interleukin-3 (IL-3) is involved in regulation of proliferation and differentiation of multipotent hemopoietic cells and stimulates the production of most blood cell types. The observed functional specificity across species concurs with an extreme rate of IL-3 amino acid substitutions during mammalian evolution. Tamarin IL-3 exhibited 70.5% sequence identity with human IL-3 and was severely impaired in supporting proliferation of human IL-3-dependent cells. In contrast, chimpanzee IL-3 displayed high amino acid sequence homology (98.5%) and could substitute for human IL-3. A panel of interspecies chimera between the chimpanzee and tamarin IL-3 genes has been constructed and expressed in Escherichia coli and eukaryotic cells to investigate the role of substitutions in different protein domains on the functional species specificity. Our analyses show that substitutions at residues encoded by the first two exons appear crucial in the functional species specificity, whereas C-terminal alterations show only moderate effects.

Amino Acid Sequence↗
PubMed1994

Interleukin-3 (IL-3) receptors on rhesus monkey bone marrow cells: species specificity of human IL-3, binding characteristics, and lack of competition with GM-CSF.

The relative affinity of recombinant human interleukin-3 (IL-3) binding to normal rhesus monkey bone marrow cells was found to be 25- to 50-fold less than that of homologous IL-3, which explained the species specificity of human IL-3 observed when tested in Macaca species. In contrast, only a small difference was found between human and rhesus monkey IL-3 in relative binding affinity for receptors on human acute myelogenous leukemia (AML) cells, which confirmed that the species specificity of IL-3 is largely unidirectional. The biological significance of the findings was demonstrated by direct in vivo comparison of the effects of high-dose recombinant rhesus monkey and human IL-3. The binding characteristics of IL-3 receptors on rhesus monkey bone marrow and peripheral blood cells were further characterized by specific binding of radiolabeled rhesus monkey IL-3. Scatchard analysis of two bone marrow samples demonstrated high-affinity IL-3 receptors (25 and 80 sites/cell, respectively; equilibrium dissociation constants [Kd] of 8 and 3 pM/L) as well as low-affinity receptors (1070 and 1290 sites/cell; equilibrium dissociation constants of 2600 and 1200 pM/L). In addition, IL-3 receptor expression was also detected on purified CD34-positive bone marrow cells. Competition by human granulocyte-macrophage colony-stimulating factor (GM-CSF) of IL-3 binding to high- or low-affinity receptors on rhesus monkey peripheral blood and bone marrow cells could not be demonstrated, which may indicate that the growth factor-specific alpha-subunits of the GM-CSF and IL-3 receptors are expressed predominantly on different cell types.

Animals↗
PubMed1994

Expression of the multidrug resistance-associated protein (MRP) in acute and chronic leukemias.

We determined the expression of the multidrug resistance-associated protein (MRP), a new putative transmembrane drug transporter, in peripheral blood cells from healthy volunteers as well as from 60 patients with acute or chronic leukemia, using an RNase protection assay. MRP appeared to be ubiquitously expressed at low levels in all nonmalignant hemopoietic cell types, reflecting its basal constitutive expression. In acute myelocytic leukemia (AML) (n = 16), one of nine untreated patients and two of seven patients with prior chemotherapy showed significant hyperexpression of MRP. In chronic lymphocytic leukemia (CLL) (n = 21), either treated (n = 8) or untreated (n = 13), a high percentage (15 of 21: 71% had relatively high expression levels of the MRP gene. In contrast, low MRP expression levels were detected in acute lymphocytic leukemia (n = 14), and in chronic myelocytic leukemia (n = 9). DNA analysis by Southern blotting did not reveal amplification of the MRP gene in the leukemia samples, including those with elevated MRP mRNA levels. We conclude that relatively high expression of MRP is occasionally observed in AML and at high frequency in CLL, irrespective of treatment, probably due to transcriptional activation and/or increased mRNA stability.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Neutralizing antibodies during treatment of homologous nonglycosylated IL-3 in rhesus monkeys.

During administration of homologous nonglycosylated IL-3 to rhesus monkeys, reversal of hematologic effects and disappearance of side effects suggested a neutralizing anti-IL-3 antibody response. Among a total of 20 monkeys treated with IL-3, ELISA of serial serum samples revealed anti-IL-3 antibodies in ten animals. Antibody production tended to be dose dependent. Triplicate subcutaneous injections and i.v. administration provoked earlier appearance of antibodies than single s.c. injection. Prolonged continuous intravenous IL-3 administration (63 and 93 days) at a dose of 1 microgram/kg/day did not result in antibody production. Among a total of eight animals with sufficiently high titers to allow for antibody purification, seven appeared to have generated antibodies that neutralized the biologic activity of IL-3 in vitro. In six monkeys, the response to IL-3 decreased while antibody titers rose, strongly suggesting neutralization of IL-3 in vivo. It is concluded that recombinant, nonglycosylated IL-3 as used in this study may elicit a neutralizing antibody response.

Animals↗
PubMed1993

Menopausal symptoms in Australian women.

OBJECTIVES: To describe Australian-born women's experience of symptoms during the natural menopause transition and the relative contribution of menopausal and health status, social factors and lifestyle behaviours. DESIGN: A community based cross-sectional survey by telephone interview was carried out on a randomly derived sample of Melbourne women. PARTICIPANTS: The participants were 2000 Australian-born women, aged between 45 and 55 years. OUTCOME MEASURES: A list of 22 symptoms was used. Explanatory variables were: sociodemographic variables; menopausal and health status; lifestyle behaviours; attitudes to ageing and to menopause. RESULTS: A 70% response rate was achieved for eligible women who could be contacted during the study. Premenopausal women were the least symptomatic and perimenopausal women the most symptomatic. Factor analysis found seven common factors from the 22 symptoms studied. Menopausal status based on menstrual history was significantly related to two groups of symptoms: vasomotor symptoms, which increased through the menopausal transition; and general somatic symptoms which were more frequent in the perimenopause. Analysis of variance of factor scores found fewer symptoms with increasing years of education, better self-rated health, the use of fewer non-prescription medications, the absence of chronic health conditions, a low level of interpersonal stress, the absence of premenstrual complaints, not currently smoking, exercise at least once a week, and positive attitudes to ageing and menopause. CONCLUSIONS: Many factors unrelated to hormonal changes contributed to the symptoms. Longitudinal investigation is needed to determine the relative importance of hormonal, psychosocial and lifestyle variables in the aetiology of mid-life symptoms.

Attitude↗
PubMed1993

IgA nephropathy and hypercalcemia in Whipple's disease.

In 2 patients an IgA nephropathy was found 2 and 5 years before gastrointestinal symptoms led to the diagnosis of Whipple's disease. One patient additionally presented with hypercalcemia. Subsequently 1 patient died, whereas treatment with trimethoprim/sulfamethoxazole resulted in an improvement of IgA nephropathy and in a complete recovery from hypercalcemia and all the manifestations of Whipple's disease in the other patient. IgA nephropathy and hypercalcemia may be considered as early manifestations of Whipple's disease.

Adult↗
PubMed1993

Transcriptional and posttranscriptional regulation of inhibin alpha-subunit gene expression in rat Sertoli cells by 8-bromo-3',5'-cyclic-adenosine monophosphate.

FSH is a major regulator of inhibin production in the testis. FSH effects on Sertoli cell inhibin production are believed to be mediated, at least in part, via the cAMP second messenger system. Previously, it has been shown that 8-bromo-cAMP (8-Br-cAMP) stimulates inhibin-alpha mRNA levels. This study examines whether the cAMP-induced increase in inhibin-alpha mRNA levels results from increased alpha mRNA synthesis, decreased degradation of mRNA, or both. The effects of cAMP on inhibin-alpha gene transcription were examined using nuclear run-on assays. Furthermore, the ability of 8-Br-cAMP to drive the transcription of chimeric constructs containing a 2.2-kilobase (kb) segment of the 5'-regulatory region of the alpha gene placed upstream of the coding region of the luciferase reporter gene was also examined. Data from nuclear run-on assays demonstrated rapid induction of alpha gene transcription by cAMP within 2 h and maximal 4- to 5-fold increase within 4-8 h in primary Sertoli cells. Transfection of TM.4 and JEG.3 cells with an alpha (2.2 kb):luciferase chimeric construct (containing 2.2 kb of the alpha gene 5'-flanking DNA) revealed rapid time-dependent induction of luciferase activity by 8-Br-cAMP in these cell types. To examine the effects of 8-Br-cAMP on alpha mRNA stability, cells were pretreated with medium or 50 micrograms/ml 8-Br-cAMP for 24 h before addition of 5 microM actinomycin D to arrest new RNA synthesis, and the decay of alpha mRNA transcripts was assessed over 24 h by Northern analysis and nonlinear regression.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1993

Acute side effects of homologous interleukin-3 in rhesus monkeys.

Interleukin-3 treatment of juvenile rhesus monkeys elicits a dose- and time-dependent syndrome that includes urticaria, palpable lymph nodes, splenomegaly, thrombocytopenia, anemia, vomiting, diarrhea, intestinal bleeding, edema, and arthritis, apart from a strong stimulation of hemopoiesis. Arthritis was found to occur significantly more often in animals expressing the major histocompatibility complex alleles B9 and Dr5. Histological analysis revealed an abundance of mast cells in urticaria and, to a lesser extent, in lungs and synovia of arthritic joints. Active osteoclasts were abundant in ribs and arthritic joints. Extramedullary hemopoiesis was encountered in liver, spleen, and kidneys. The spleen showed deposits of hemosiderin, and in the liver, Kupffer cells were loaded with iron, indicating enhanced turnover of hemoglobin. Lymph nodes and bone marrow showed macrophages involved in hemophagocytosis, which probably contributed to the development of anemia and thrombopenia. Biochemical parameters in sera were indicative of parenchymal liver damage, with cholestasis and increased erythrocyte destruction. The side effects were strongly reduced in monkeys subjected to total body irradiation just before interleukin-3 treatment. Histamine antagonists were not significantly effective in preventing side effects, which is explained by the perpetual stimulation of basophilic granulocytes by exogenous interleukin-3. The nature of the side effects indicates that interleukin-3 may be involved in the pathogenesis of acute type hypersensitivity reactions and arthritis.

Anemia↗
PubMed1993

Pharmacokinetic basis for optimal hemopoietic effectiveness of homologous IL-3 administered to rhesus monkeys.

To design an interleukin-3 (IL-3) administration schedule for optimal hemopoietic effectiveness, serum half-life (t1/2) was determined after intravenous (i.v) and subcutaneous (s.c.) bolus injections. The initial t1/2 in serum after i.v. injection was about 10 minutes and the terminal t1/2 close to 2 hours. Subcutaneous administration resulted in plateau levels after 2 to 4 hours, while the apparent terminal t1/2 was similar to that after i.v. infusion. The bioavailability of IL-3 following subcutaneous administration was only about 40% of that following i.v. administration. Hemopoietic effects of continuous i.v. infusion of IL-3 was then compared to s.c. administration in either one, two, or three daily injections. Doses chosen ranged from 1 to 30 micrograms/kg per day. In agreement with the more limited bioavailability of IL-3 following s.c. administration, continuous i.v. infusion was much more effective in stimulating hemopoiesis than s.c. administration. Two or three daily s.c. injections did not improve the hemopoietic response compared to a single s.c. injection, which is in agreement with the apparent terminal t1/2 of 101 min. It is concluded that IL-3 is more effective by continuous i.v. infusion than by subcutaneous administration.

Animals↗
PubMed1992

Age related changes in follicle stimulating hormone, luteinizing hormone, oestradiol and immunoreactive inhibin in women of reproductive age.

OBJECTIVE: In women over the age of 45 years with continuing regular menstrual cycles, follicular phase FSH levels rise without an accompanying change in LH. We determined the effect of increasing age in women with regular cycles on the serum levels of FSH, LH, immunoreactive inhibin, progesterone and oestradiol. DESIGN: Single blood samples were taken during the early follicular phase (days 4-7) and again in the midluteal phase (3-12 days before the next menses) of the menstrual cycle. PATIENTS: Regularly cycling women aged 21-49 years participated in the study (and were grouped into four groups: 20-29, 30-39, 40-44 and 45-49 years in the follicular phase and three groups: 20-29, 30-39 and 40-49 years in the luteal phase. MEASUREMENTS: Serum levels of FSH, LH, oestradiol, progesterone and immunoreactive inhibin were measured from the blood samples obtained. RESULTS: Follicular phase Mean follicular phase levels of immunoreactive inhibin were significantly lower in the 45-49 year age group (P less than 0.05) than in the younger age groups (128 U/l in the 45-49 year age group vs 239, 235 and 207 U/l in the 20-29, 30-39, 40-44 year age groups respectively), while mean FSH levels were significantly higher in the 45-49 year age group (P less than 0.05, 13.0 IU/l in the 45-49, 4.9, 5.5 and 5.2 IU/l in the 20-29, 30-39 and 40-44 year age groups respectively). Mean oestradiol levels in the 45-49 year age group were significantly lower only when compared to age group 30-39 years (P less than 0.05, 130 vs 210 pmol/l). There was no significant difference in oestradiol levels between the 45-49 year age group and the 20-29 and 40-44 year age groups. LH levels did not differ significantly across age groups. There was also a significant negative correlation between serum immunoreactive inhibin and FSH (r = -0.45, P less than 0.05) and between oestradiol and FSH (r = -0.35, P less than 0.05). There was a significant negative relationship between immunoreactive inhibin and age (r = -0.46, P less than 0.05). For every 10-year increase in age, average immunoreactive inhibin decreased by an estimated 49.3 U/l. As age increased, average FSH levels exhibited a two-phase linear increase with the change-point estimated at 42.97 (1.42) (estimate (SE)) years. Prior to 42.97 years, FSH barely changed; after 42.97 years there was a significant (P less than 0.05) increase in FSH as age increased. Oestradiol levels did not change significantly until an estimated 37.9 years of age, but then decreased significantly (P less than 0.05) with increasing age. Luteal phase Levels of FSH, LH, serum immunoreactive inhibin, oestradiol and progesterone fell slowly with increasing age. There was a significant correlation between serum immunoreactive inhibin with progesterone (r = 0.41, P less than 0.05) but there was no correlation between serum immunoreactive inhibin LH or FSH. CONCLUSION: The results are consistent with a role for serum immunoreactive inhibin, in addition to oestradiol, in the regulation of FSH during the follicular phase of the menstrual cycle as a function of increasing age. This is postulated to reflect diminished folliculogenesis as age progresses with the known decline in the numbers of primordial follicles in the ovary as the menopause approaches.

Adult↗
PubMed1992

Circulating immunoreactive inhibin and testosterone levels in men with critical illness.

OBJECTIVE: We aimed to concurrently characterize serial changes in circulating immunoreactive inhibin (irINH) and testosterone (T) as reflections of Sertoli and Leydig cell responses to acute critical illness in man. DESIGN: Blood samples were drawn within 24 hours of admission to an Intensive Care Unit and at weekly intervals thereafter for up to 4 weeks while the patient remained in Intensive Care Unit or after discharge to a general ward. PATIENTS: We studied 13 male subjects with critical illness requiring intensive therapy. MEASUREMENTS: Plasma levels of irINH, T, LH, FSH and sex hormone binding globulin (SHBG) were analysed in relation to (i) the severity of illness as indicated by a sepsis score, acute physiology and chronic health evaluation score, and reverse triiodothyronine (rT3) levels and (ii) the outcome of illness as determined by discharge from Intensive Care Unit and the two-month mortality. RESULTS: Overall irINH levels remained normal and correlated negatively with rT3 (r = -0.63, P = 0.001) but not with sepsis, acute physiology and chronic health evaluation score, or gonadotrophin levels. Neither admission nor serial irINH levels significantly distinguished between the different clinical outcomes. In contrast, T levels were depressed and inversely correlated with both sepsis and acute physiology and chronic health evaluation scores (P less than 0.02), and positively with gonadotrophins (P less than 0.01), but not rT3 levels. Men eventually discharged from the Intensive Care Unit showed a rise, while those remaining showed a fall, in T levels (P = 0.02, time-course interaction). Similarly, T levels were lower in patients who died than in survivors, despite the comparable T levels on admission (P = 0.02, time-course interaction). Despite the fall in T levels, gonadotrophin levels remained inappropriately in the eugonadal range but higher in men who were discharged from Intensive Care Unit (P = 0.02, time-course interaction). FSH but not LH levels were correlated with sepsis score (P = 0.02) but not acute physiology and chronic health evaluation score or rT3. CONCLUSIONS: Sertoli cell function as judged by circulating irINH levels is much less affected by acute critical illness than is Leydig cell function as judged by circulating T levels. The suppressive effect of acute critical illness on Leydig cell function is consistent with a hypothalamic-pituitary lesion.

Acute Disease↗
PubMed1992

GnRH agonist analog therapy in advanced/recurrent granulosa cell tumors: further evidence of a role of inhibin in monitoring response to treatment.

Five patients with advanced ovarian granulosa cell malignancies resistant to cytotoxic chemotherapy were treated with monthly subcutaneous injections of long-acting gonadotropin releasing hormone (GnRH) agonist analog. One partial response and one stabilization of the disease were observed. In three patients, the tumor continued to progress. Treatment response was monitored with serum inhibin assay. Four patients had high serum inhibin concentrations at the beginning of GnRH analog treatment, while one patient had an inhibin-negative tumor. In three of four patients, serum inhibin remained relatively constant, or decreased during the first 3 months of therapy. It subsequently increased, in parallel with clinical deterioration. Further clinical trials with GnRH analogs are warranted in this malignancy in which serum inhibin appeared to be a clinically valuable tumor marker.

Adult↗
PubMed1992

No osteoporosis detected by quantitative computed tomography in postmenopausal black females.

Problems associated with postmenopausal osteoporosis are believed to be almost non-existent in black South African females, but published data on their bone mineral density are lacking. In this study, vertebral quantitative computed tomography was performed on 30 postmenopausal black women with no complaints other than those attributable to oestrogen deficiency. The mineral bone density was plotted against those 'normals' of similar age provided by the Somaton DR H (Siemens) data base. In all instances the vertebral bone mineral density obtained was higher in the study group.

Adult↗
PubMed1991

Evolution of human immunodeficiency virus type 1 nucleotide sequence diversity among close contacts.

The degree of change in the nucleotide sequence of human immunodeficiency virus type 1 (HIV-1) that occurs when it is transmitted sexually from one individual to another or vertically from mother to child is unknown. Previous studies have shown that most cultured HIV-1 isolates from the same individuals differed in the entire envelope gene nucleotide sequence by up to 2%, although most isolates from unrelated individuals differed by 6-22%. To examine diversity among HIV-1 isolates from close contacts, we determined the nucleotide sequences of viruses from a family with a known epidemiologic profile, in which a woman transmitted HIV-1 heterosexually to her partner and vertically to her daughter. Direct DNA sequence analysis of primary HIV-1 isolates amplified by PCR was used to distinguish the major and minor viral sequences, termed quasispecies, to rapidly determine the predominant sequences and their phylogenetic relationships. The nucleotide sequence diversity of a major portion of the HIV-1 envelope gene was 3.7% between isolates from the woman and her heterosexual partner and 8.5% between isolates from this woman and her daughter, who had been infected for a longer period than the partner. The configuration of the phylogenetic tree demonstrated that the daughter's predominant isolate evolved from a progenitor of her mother's current strain. This study provides evidence of a continuous spectrum of sequence diversity between any two isolates ranging from those derived from the same person to those from close contacts and, ultimately, those from unrelated individuals. These data and methods can be applied to epidemiologic investigations of possible HIV-1 transmission between health care workers and their patients.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Receptor and antibody interactions of human interleukin-3 characterized by mutational analysis.

Human interleukin-3 (hIL-3) is a regulator of proliferation and differentiation of multipotent hemopoietic progenitor cells. Mutants of hIL-3 have been constructed by oligonucleotide-directed mutagenesis and expressed in Escherichia coli and Bacillus licheniformis. Purified muteins were assayed for induction of DNA synthesis in IL-3-dependent human cells and for binding to the IL-3 receptor. Residues at the NH2 and COOH termini together comprising one-quarter of the molecule could be removed without loss of biological function. Deletions of 6-15 residues within the central part of the molecule caused a large reduction (up to 5 logs) but no complete loss of activity. Substitution of evolutionary conserved residues resulted in a strong decrease of biological activity and demonstrated that the S-S bridge is an essential structural element in hIL-3. Interestingly, four muteins displayed a significantly higher potency of binding to the IL-3 receptor than in stimulating DNA synthesis. These results demonstrate that receptor binding may be (partly) disconnected from activation of DNA synthesis. Analysis of hIL-3 muteins demonstrated that the majority of monoclonal antibodies are directed against a small portion of the IL-3 molecule. The neutralizing potential of individual monoclonal antibodies could be increased by a combination of antibodies directed against nonoverlapping epitopes.

Amino Acid Sequence↗
PubMed1991

Production of human interleukin-3 using industrial microorganisms.

We expressed a cDNA encoding the multicolony stimulating factor interleukin-3 in a variety of cell types, including bacteria, yeast and mammalian cells. After evaluation of the advantages and disadvantages of each potential system, we designed a production and purification scheme using Bacillus licheniformis. The purification consists of hydrophobic interaction chromatography, two steps of ion exchange chromatography and gel filtration. The purified and formulated product entered clinical trials in November 1989.

Animals↗