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Biomedical subjects

S Klaus

Publications and source records attributed to S Klaus.

At least 55 records · Page 3Linked to original sources
PubMed1995

Control of beta 3-adrenergic receptor gene expression in brown adipocytes in culture.

Brown adipose tissue is a mammalian thermogenic tissue. Its ability to dissipate energy as heat is due to a unique mitochondrial protein, uncoupling protein (UCP). Activation and expression of UCP is under control of the sympathetic nervous system acting through beta -adrenergic receptors (AR). In this study we used Siberian hamster brown adipocytes differentiated in vitro to investigate the expression of the fat specific beta 3-AR. Binding studies using the new labelled beta 3 adrenergic ligand [3H]SB 206606 showed a density of beta 3-AR in brown adipocyte plasma membranes comparable to that measured in vivo. beta 3-AR mRNA expression was very high in mature brown adipocytes and was started to be expressed during differentiation before UCP mRNA. Its half-life was approximately 50 min. Treatment of cells with non-specific beta adrenergic agonists, specific beta 3-adrenergic agonists, and dibutyryl cyclic AMP resulted in a marked down regulation of beta 3-AR mRNA level within several hours.

Adipose Tissue, Brown↗
PubMed1995

Permethrin resistance in the head louse Pediculus capitis from Israel.

Head lice, Pediculus capitis, were collected from children aged 3-12 years in Maale Adumin, a town near Jerusalem, after reports of control failure with the pyrethroid insecticide permethrin. A total of 1516 children were examined: living lice and eggs were found on 12.1% of the children; or another 22.8% of the children only nits were found. Twice as many girls as boys (8.1% v 4%) were infested with lice and or nits. Head lice collected from infested children were exposed to permethrin impregnated filter-papers. Log time probit mortality (ltp) regression lines were calculated for mortality data and compared to ltp lines for a similar collection of head lice made in 1989. The regression lines for the two years were significantly different, with a 4-fold decrease in susceptibility at the LT50 level between 1989 and 1994. The slopes of the lines also suggested that the 1994 population was more heterogenous in its response to permethrin than the 1989 population. In contrast, a laboratory population of body lice (Pediculus humanus) tested with the same batch of permethrin-impregnated papers showed a slight but non-significant increase in susceptibility between 1989 and 1994. The results suggest that resistance to pyrethroids has developed rapidly among head lice since permethrin was introduced in 1991 as a pediculicide in Israel.

Animals↗
PubMed1995

Functional assessment of white and brown adipocyte development and energy metabolism in cell culture. Dissociation of terminal differentiation and thermogenesis in brown adipocytes.

We investigated the effect of insulin, triiodothyronine (T3) and dexamethasone (a synthetic glucocorticoid) on differentiation, lipid metabolism and thermogenesis of preadipocytes isolated from white fat (WAT) and brown fat (BAT) from the Siberian dwarf hamster (Phodopus sungorus). Cell cultures from WAT and BAT were chronically treated with the above hormones alone or in any combination. After differentiation (day 8 or 9 of culture) we measured the following parameters: adipogenic index (number x size of adipocytes), protein content, lipolysis, cell respiration, and expression of the uncoupling protein UCP, which is unique to mitochondria of brown adipocytes. Insulin was the most important adipogenic factor for brown and white adipocytes and necessary for terminal differentiation, whereas dexamethasone alone completely inhibited differentiation. T3 had no effect on adipogenesis in WAT cultures, but further increased insulin stimulated adipogenesis in BAT cultures. Basal lipolysis was higher in WAT than in BAT cultures except when dexamethasone was present, which stimulated lipolysis in both culture types to the same extent. T3 had a pronounced dose dependent lipolytic effect on WAT cultures but very little effect on BAT cultures. Respiration rates were generally higher in differentiated adipocytes than in fibroblast like cells. T3 had no effect on thermogenesis in WAT cultures but increased thermogenesis in BAT cultures, and this was further elevated by insulin. UCP expression in BAT cultures could be detected by western blot in insulin treated, T3 treated and insulin+T3 treated cultures with highest expression in the latter. These results imply a possible dissociation of terminal differentiation and thermogenic function of brown adipocytes. In WAT cultures there was also a low level of UCP detectable in the insulin+T3 treated cultures. Immuno-fluorescence microscopy analysis revealed the presence of UCP in 10-15% of adipocytes from WAT cultures (in BAT cultures: 90%), indicating the presence of some brown preadipocytes in typical WAT deposits.

Adipocytes↗
PubMed1994

Antigen presentation by epidermal Langerhans cells in experimental cutaneous leishmaniasis.

Cutaneous leishmaniasis is a disease induced by intradermal injection of leishmania promastigotes. Since the first cells the parasite encounters are those of the skin, the involvement of this organ in the early immune response might be relevant to the outcome of the disease. In this study we examined the ability of epidermal langerhans cells (LC) to become infected in vivo and to function as antigen presenting cells during the early hours of infection with Leishmania major. Our experiments showed that LC from mice injected with parasites can present antigen to a leishmania-specific T cell line when LC are obtained as early as four h after infection. The stimulation was specific, since LC from leishmania injected mice did not present antigen to an ovalbumin-specific T cell line nor did LC from ovalbumin-injected mice present antigen to the leishmania specific T cell line. Despite the ability of epidermal LC cells to present antigen, no parasites were detected in the epidermis, suggesting that these cells are not directly involved in establishing an infection.

Animals↗
PubMed1994

Generalized infestation of a 3 1/2-year-old girl with the pubic louse.

A 3 1/2-year-old girl had a Pthirus pubis infestation of the scalp, neck, eyelashes, back, and pubic area. The child's body, including the scalp, was treated with a 1% permethrin cream rinse formulation for 10 minutes. The treatment was repeated after 10 days. The eyelashes were treated by application of the permethrin solution with a cotton-tip swab.

Child, Preschool↗
PubMed1994

Characterization of the novel brown adipocyte cell line HIB 1B. Adrenergic pathways involved in regulation of uncoupling protein gene expression.

The HIB 1B cell line, derived from a brown fat tumor of a transgenic mouse, is the first established brown adipocyte cell line capable of expressing the brown fat-specific mitochondrial uncoupling protein (UCP). UCP gene expression, which was virtually undetectable under basic conditions, was stimulated by acute catecholamine or cyclic AMP treatment to levels comparable to primary cultures of brown adipocytes. Elevation of UCP mRNA levels following stimulation was very rapid but transient, decreasing after about 4 hours with a half-life between 9 and 13 hours. Immunoblotting showed the presence of UCP in HIB 1B mitochondria, but expression was much lower than observed in BAT or primary cultures of brown adipocytes. Upon transfection of HIB 1B cells with a reporter gene containing the UCP promoter, the activity of the transgene was regulatable by cAMP and norepinephrine. Investigation of the possible adrenergic receptors involved in UCP stimulation showed that specific beta 3-adrenergic agonists were much less effective than nonspecific beta-adrenergic agonists and that mRNA levels of the atypical, fat-specific beta 3-adrenoceptor were lower than those observed in brown adipocytes differentiated in primary culture. From pharmacological evidence we conclude that beta 3-adrenergic receptors account for approximately 30-40% of catecholamine induced UCP gene stimulation, whereas about 60-70% is stimulated via the classical beta 1/2 adrenergic pathway. We conclude that HIB 1B cells represent a functional system for the study of mechanisms related to brown adipose thermogenesis.

Adipocytes↗
PubMed1993

A kindred with Griscelli disease: spectrum of neurological involvement.

We report four members of a highly consanguineous family with silver-grey pigmentation of hair, two of whom had skin histology compatible with Griscelli disease. Unlike previously reported patients, they did not suffer from recurrent infections. In addition, there was a spectrum of neurological involvement varying from mild cognitive delay with a convulsive disorder in one patient, to a fatal degenerative course in three others. One patient developed a prolonged febrile illness with histological evidence of florid lymphoid hyperplasia.

Child, Preschool↗
PubMed1993

Effect of topical paromomycin on cell-mediated immunity during cutaneous leishmaniasis.

BACKGROUND: The aim of this study was to evaluate the effect of topical paromomycin treatment on the development of immunity during cutaneous leishmaniasis. METHODS: Three parameters of immunity were measured in the course of the disease: leishmanicidal effector activity, lymphocyte proliferation (cell-mediated immunity), and antibody levels (humoral immunity). Peripheral blood specimens of 55 treated and 36 untreated patients were tested. RESULTS: The main results of this study showed that there was a significant delay in the development of leishmanicidal effector activity and to a lesser extent also a delay in the development of antigen-specific proliferative response in the treated compared with the untreated group. No difference was observed between the groups regarding the values achieved in the various tests. CONCLUSIONS: These results suggest that topical paromomycin treatment delays the development of cell-mediated immunity but does not affect the levels of immunity that are eventually achieved.

Administration, Cutaneous↗
PubMed1993

Tissue-specific and beta-adrenergic regulation of the mitochondrial uncoupling protein gene: control by cis-acting elements in the 5'-flanking region.

Uncoupling protein (UCP) gene expression is tightly restricted to thermogenic brown adipocytes and is rapidly activated by norepinephrine released after cold exposure. To identify cis-acting regulatory elements controlling this gene, a region encompassing 4.5 kilobases of DNA upstream of the transcription start site was analyzed using hybrid UCP-chloramphenicol acetyltransferase reporter gene constructs. Evidence for the presence of both tissue-specific and beta-adrenergic response elements in this 4.5-kilobase region was obtained by comparing the expression of these reporter genes in transfected brown adipocytes (in vitro differentiated), brown preadipocytes, white adipocytes, and Chinese hamster ovary (CHO) cells and from experiments in transgenic animals. Deletion analyses in transfected cells indicated that the minimal region exhibiting promoter activity and tissue specificity is located between -157 and -57 base pairs (bp). A 211-bp activator element located between -2494 and -2283 bp was necessary for full expression in brown adipocytes. This element also activated expression of the homologous -157-bp promoter and expression of a heterologous promoter in both brown adipocytes and CHO cells. A second region, downstream of the activator and possibly located between positions -400 and -157 bp, inhibited the UCP promoter in CHO cells. In mice transgenic for a chloramphenicol acetyltransferase reporter gene containing these elements, expression was both tissue specific and regulatable by environmental temperature changes. These results indicate that both positive and negative cis-acting elements participate in the regulation of UCP gene expression.

Adipose Tissue, Brown↗
PubMed1993

Development of in vitro parameters of cell-mediated immunity in the course of human cutaneous leishmaniasis infection.

The goal of the present study was to determine whether a correlation between the clinical stage of cutaneous leishmaniasis lesions and in vitro parameters of cell-mediated immunity could be established. For this purpose, we measured lymphocyte proliferation, using a total lymphocyte proliferation (TLP) blood assay, and leishmanicidal effector activity using peripheral blood mononuclear cells (PBMC) in a three-day assay. The parameters of leishmanicidal activity measured included percent infected monocytes and number of amastigotes per 100 infected monocytes 24 and 72 hr after infection. Three groups of people were studied: a group of patients in the course of the disease, a group of immune individuals, and unexposed controls. The results of the study suggested that the ability of PBMC to kill parasites increased in patients as the lesions cured, and was highest in immune individuals. In contrast, the TLP response once positive, did not increase after cure. In approximately 30% of the patients who were retested on several occasions during the course of the disease, a positive response reversed to negative both in the TLP and the effector assays while the lesions were still active. In approximately 50% of these cases, the response eventually became positive again. The data presented show that effector activity and proliferation correlate with immunity, and suggest that marked heterogeneity characterizes the immune response in the course of active disease.

Animals↗
PubMed1992

Hibernoma formation in transgenic mice and isolation of a brown adipocyte cell line expressing the uncoupling protein gene.

Transgenic mice were produced containing the adipocyte-specific regulatory region from the adipocyte P2 (aP2) gene linked to the simian virus 40 transforming genes. Most of the transgenic mice developed brown fat tumors (hibernomas) in their interscapular brown adipose tissue. Hibernoma formation was noticeable in some of the mice as early as 1 day after birth and most of the mice developed very large tumors by 1 month of age. All of the tumor tissue expressed the brown fat-specific uncoupling protein (UCP) gene as well as the aP2 gene. Several of the tumors have been used to establish cultured cell lines and at least one of these lines can be induced to differentiate into brown adipocytes. The cultured adipocytes express mRNA for UCP upon stimulation with N6,O2'-dibutyryladenosine 3',5'-cyclic monophosphate, norepinephrine, isoproterenol or D7114, a beta 3 adrenergic agonist. Thus, regulation of the key thermogenic gene UCP can now be studied in an established cell line.

Adipose Tissue, Brown↗
PubMed1992

Antibodies selected from whole antiserum by fusion proteins as tools for the study of the topology of mitochondrial membrane proteins. Evidence that the N-terminal extremity of the sixth alpha-helix of the uncoupling protein is facing the matrix.

The reactivity to freeze-thawed mitochondria or submitochondrial particles of a whole antiserum raised against the uncoupling protein has been investigated. Incubation with freeze-thawed brown adipose tissue mitochondria trapped antibodies reactive toward accessible parts of the uncoupling protein. One-third to one-half of antibodies against uncoupling protein which were present in the serum remained free. These antibodies were highly reactive with the vesicles obtained by sonication of mitochondria, in which the matricial side of the inner membrane was made accessible. To define epitopes recognized by the antiserum, different fusion proteins made up of MalE protein and uncoupling protein fragments were used. Immunoaffinity chromatography, using an immobilized purified fusion protein containing amino acids 253 to 290 of uncoupling protein, selected antibodies specifically directed against this part of the protein. A more precise localization of the main epitope recognized by these antibodies is proposed. These purified antibodies reacted with the protein only in submitochondrial particles, indicating a matricial orientation of this epitope. This result, associated with other data concerning uncoupling protein or related mitochondrial carriers such as the ADP/ATP translocator and the phosphate carrier, allowed us to determine the orientation of the sixth alpha-helix of the uncoupling protein.

Amino Acid Sequence↗
PubMed1992

Human cutaneous leishmaniasis: in-vitro parasite--mononuclear cell interactions in immune and naive individuals.

The aim of this study was to compare the ability of Leishmania parasites to survive in mononuclear cells from immune individuals with their ability to survive in cells from naive individuals. For this purpose we established an in vitro system based on the co-culture in suspension of human peripheral blood leukocytes derived from immune and naive subjects and L. major promastigotes. The proportion of monocytes containing intracellular parasites and the number of amastigotes per 100 infected monocytes (parasite burden) were determined 24 and 72 h after in-vitro infection. The proportion of infected cells from naive individuals did not change, and the number of amastigotes either did not change or increased by 1.2 to 1.7-fold between 24 and 72 h incubation. In contrast, in the immune subjects, the proportion of infected monocytes 24 h after infection was lower than in the naive individuals, and a 30-90% decrease in both the proportion of infected monocytes and the parasite burden was observed after 72 h incubation. Based on these results, three characteristics of leishmanicidal activity of mononuclear cells from immune individuals were determined: (a) the proportion of infected monocytes 24 h after infection was lower than 22%; (b) there was a decrease of more than 30% in the proportion of infected monocytes between 24 and 72 h after infection; and (c) there was a significant decrease in the number of amastigotes between 24 and 72 h after infection. The results of this study demonstrate an enhanced leishmanicidal activity of mononuclear cells from immune individuals.

Humans↗