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Biomedical subjects

H Hauser

Publications and source records attributed to H Hauser.

At least 73 records · Page 4Linked to original sources
PubMed1997

A sensitive method for the detection of murine C-type retroviruses.

A RT-PCR assay was developed for group-specific detection of murine C-type retroviruses using a nested set of degenerated primers. To distinguish exogenous viruses from related, but silent endogenous viruses, a DNAse I pretreatment of supernatants is applied. This is followed by a heat inactivation/denaturation step. The PCR method is ultrasensitive. which enables the detection of 100 attogram of MoMuLV proviral DNA or up to 1-10 infectious mouse C-type retroviruses in 10 microl supernatant of infected cells. The high specificity of the method allows the differentiation between mouse C-type retroviruses and related retroviruses of the A, B, and D type and C-type retroviruses found in other species. It serves as a valuable tool for the screening of animal cell cultures for contaminations with mouse retroviruses, e.g. hybridomas or recombinant cell lines producing foreign proteins.

3T3 Cells↗
PubMed1997

The transcriptional silencer protein NRF: a repressor of NF-kappa B enhancers.

NF-kappa B/rel proteins are present in most cell types. In concert with other transcriptional factors they regulate a variety of genes which contribute to a wide spectrum of physiological activities like inflammation and apoptosis. An excellent example of this combinatorial regulation takes place in the IFN-beta promoter. In this promoter the fundamental regulatory elements are assembled within less than 100 base pairs including a NF-kappa B/rel enhancer and a negative regulatory element, called NRE. NRE is a member of a new class of transcriptional repressor sequences with a silencing capacity targeted to the NF-kappa B/rel enhancer. NRF is a novel transcriptional factor that binds to NRE. NRF belongs to a major class of transcriptional repressors that interact with specific promoter elements and repress transcription by separable repression domains. Such molecules have been termed active repressors, because they act by inhibitory protein-protein interaction and not simply by steric hindrance.

Binding Sites↗
PubMed1997

Cystic retroperitoneal lymphangiomas in adults.

Lymphangioma (LA) is a rare benign tumour of the lymphatic tissue, most common in the neck and head, and clinically manifests itself mostly in childhood. Within this group, intra-abdominal and retroperitonal LA are the rarest tumours, especially when occurring in adults. We report four LAs localized in the retroperitoneum of patients aged between 28 and 72 years. One of these tumours infiltrated the transverse mesocolon and greater omentum, others were situated in the left retroperitoneum and retroperitoneally at the duodeno-jejunal flexure, and in the retrosplenal and retropancreatic area. Diagnosis was made by light microscopy supported by immunohistochemistry. In three cases the tumour could be removed by radical surgery and none of these patients had a recurrence (median follow-up time: 4 years). The tumour could not be removed completely from one patient with pre-operative chylascos. Six months after diagnosis of LA this patient died of cardiopulmonary failure due to progressive tumour chylascos. Isolation and ligation of the cystic LA's peduncle as well as ligation of lymph channels can prevent recurrences and chylascos.

Adult↗
PubMed1997

Experience with a high speed biopsy gun in breast cancer diagnosis.

Pre-operative determination of histology and receptor status is important in optimizing the management of breast cancer. The purpose of our study was to evaluate the high speed biopsy gun in 109 patients with palpable breast tumours. High speed biopsies were performed using the system BIP High Speed Multi 22 with 16-gauge-needles at a speed of 30 m/s. All biopsies could be used for frozen sections and for determination of receptor status. In 81 patients (74.3%) malignant breast tumours were diagnosed, and three patients (2.8%) had highly suspicious lesions. The oestrogen receptor status was negative in 32%, progesterone receptor status negative in 41%. In one patient (0.9%) a high grade non-Hodgkin's lymphoma of B-cell-type was diagnosed. In 21.1% benign tumours were found. In one patient a malignant tumour was missed at biopsy (0.9% false-negative). It was concluded that high speed biopsy is a reliable and simple method for preoperative sampling of breast lesions.

Biopsy, Needle↗
PubMed1997

Endocavitary Ir-192 radiation and laser treatment for palliation of obstructive rectal cancer.

Endoscopic laser therapy (ELT) either alone or combined with endocavitary Ir-192 radiation is performed for advanced, inoperable rectal cancer and when patients are ineligible for surgery due to severe concomitant medical illness. During the period from January 1984 to January 1997 we treated 81 patients (51 males, 30 females). Sixty-seven patients had ELT only using a ND-Yag Laser system. Twenty-five patients (average age: 80.5 years) were ineligible for surgery (Group I). Forty-two patients (74.1 years) had an advanced locally inoperable tumour (Group II). Fourteen patients (76.5 years) underwent a combined therapeutic regime with endocavitary Ir-192 afterloading following ELT (Group III). Adequate desobliteration was achieved in 100% (groups I and III) and 97% (group II) of the patients. The average interval to aftertreatment was 8.4 weeks in group I and 9.4 weeks in group II, compared to 11.5 weeks in group III. Serious complications (perianal abscess, rectovaginal fistula) occurred in 3.7%, minor complications (laser-induced bleedings, unclear fever) in 12.3%. All laser-induced bleedings could be dealt with using laser therapy. The frequency of treatment was governed by tumour mass and the patient's survival. The results suggest that additional endocavitary radiation significantly prolongs the maintenance of normal bowel function compared with laser therapy alone.

Aged↗
PubMed1996

Translational recoding induced by G-rich mRNA sequences that form unusual structures.

We investigated a herpesvirus mutant that contains a single base insertion in its thymidine kinase (tk) gene yet expresses low levels of TK via a net +1 translational recoding event. Within this mutant gene, we defined a G-rich signal that is sufficient to induce recoding. Unlike other translational recoding events, downstream RNA structures or termination codons did not stimulate recoding, and paused ribosomes were not detected. Mutational analysis indicated that specific tRNAs or codon-anticodon slippage were unlikely to account for recoding. Rather, recoding efficiency correlated with the G-richness of the signal and its ability to form unusual structures. These findings identify a mechanism of translational recoding with unique features and potential implications for clinical drug resistance and other biological systems.

Amino Acid Sequence↗
PubMed1996

Retroviral infection of Syrian hamster BHK cells depends on age and susceptibility toward sialidase.

Infection with recombinant retroviruses is a standard method to efficiently manipulate murine or human cells genetically. Due to differences in glycosylation of the hamster homologue to the murine ecotropic receptor and the absence of an amphotropic receptor, murine retroviruses are unable to infect hamster cells. Here we describe an isolated cell clone of the Baby Hamster Kidney cell line, BHK-21, that can be successfully infected with ecotropic murine retroviruses. This finding prompted us to investigate the possibility of changing the infectability of other cell strains by manipulating the receptors of these cell lines in vitro. We found that treatment of other BHK cell clones with sialidase from C. Perfringens makes these cell clones also permissive to murine ecotropic retroviruses. Long term cultivation of three tested cell clones increased this susceptibility. Although the resulting infectants show a higher rate of infectability, they still require the manipulation with sialidase for this superinfection to be efficient.

3T3 Cells↗
PubMed1996

On the use of double FLP recognition targets (FRTs) in the LTR of retroviruses for the construction of high producer cell lines.

A pilot experiment for the construction of a hamster derived, high producer cell line using site specific recombination is described. In the experiment chromosomal loci with intrinsic high expression characteristics were sought via infection with a retroviral construct, containing double FRT sites and subsequent screening for overproduction of an encoded markergene. These sites were then targeted with a second vector, that recombined via the FLP/FRT system from Saccharomyces cerevisiae yielding cells that had the second construct at exactly the same position as the first. By using retroviral vectors with double and single FRT sites, respectively, stable clones can be created that can no longer be excised with FLP.

Animals↗
PubMed1996

Vascular complications of lumbar disc surgery.

Over a period of seven years nine patients with vascular complications after lumber discectomy received medical care at the Clinic of Vascular Surgery, University of Graz Medical School. We report five acute bleeding complications occurring during the operation and four late manifestations of vascular lesions. Five patients presented with acute life-threatening iatrogenic haemorrhages from pelvic vessels. Three patients made a complete recovery, one patient died from acute haemorrhagic shock, one further patient died from sepsis due to an associated complication-an injury to the ureter. Over a period of two to ten years after primary surgery we corrected late complications such as 1 case of posttraumatic aneurysm of the aortic bifurcation found to have eroded the body of the fifth lumbar vertebra, and three cases of arteriovenous fistula between the common iliac artery and the common iliac vein. The four cases described below are an attempt to document the vascular surgical procedures involved and to provide typical findings. The risk of injuring the pelvic vessels intra-operatively can be explained by the close anatomical relation between the retroperitoneal vessels and the vertebral column and furthermore not only by the fact that pre-existent deficiencies but also injury to the anterior longitudinal ligament give access to the retroperitoneal space.

Adult↗
PubMed1996

Paragangliomas of the carotid bifurcation: oncological aspects of vascular surgery.

The present study reviews in concise form the past 12 years of our clinical experience with paragangliomas of the carotid body. Every aspect of the anatomical, histological and biological and biological behaviour of paragangliomas of the carotid body has been recorded in order to be able to define better surgical management and the clinical prognosis. In addition to the conventional histological methods of investigation we also applied immunohistochemistry and made use of electron microscopy. Eighteen tumours of the carotid body in 12 female and four male patients with a mean age of 54 years (34 to 70 years) were treated surgically. Angiography of the aortic arch and supra-aortic branches was undertaken diagnostically in every case. In three patients computer tomography and magnetic resonance imaging demonstrated spreading of the tumour up to the base of the skull and pre-operative embolization of the arteries supplying the tumour was performed to decrease tumour vascularity. In four cases (22%) resection of the internal carotid artery and its reconstruction by a saphenous vein graft was required in order to achieve the therapeutic aim of a complete extirpation of tumourous tissue and preserving the vascular system of the internal carotid artery. In three cases (16%) there was histological evidence of a metastasizing process to the local lymph nodes of the neck and, due to this criterion of malignancy, 50-60 Gy of radiation was applied to the site of the tumour after surgery. Four patients experienced a transient neurological deficit in the supply area of the hypoglossal and the recurrent nerves. In one case, the vagus nerve could not be retained. In an average follow-up of 102 months we recorded one case of local recurrence 13 months after the initial resection and radiation treatment applied to a malignant paraganglioma. All the other patients were doing well without evidence of recurrent disease.

Carotid Body Tumor↗
PubMed1996

Regulated ribosomal frameshifting by an RNA-protein interaction.

Ribosomal frameshifting is a translational mechanism used as an essential step in the replication cycle of retroviruses. Programmed frameshifting in retroviral translation involves two sequence elements: A heptanucleotide slippery sequence which induces a low basal level of frameshifting and a downstream RNA structure as an enhancer of the process. The precise mechanism of function of these downstream elements is still unclear, but their effect does not solely depend on their stability. Likewise, the possibility that frameshifting could be controlled by specific proteins that bind to these elements and enable or modulate their effects has yet not been substantiated. The RNA hairpin of the HIV-1 gag-pol frameshift cassette was replaced by the iron-responsive element (IRE) from ferritin mRNA, a stem-loop structure that binds iron regulatory proteins (IRPs) in dependence of the iron status of the cell. When a lacZ/luciferase reporter construct was expressed in transfected BHK-21 cells, the IRE or a point-mutated version that is unable to bind IRPs were found to functionally substitute for the HIV-1 hairpin. When cells were treated with the iron chelator desferrioxamine to stimulate IRP binding to the wild-type IRE, frameshift activity was specifically and strongly augmented by protein binding Our data establish that frameshifting can be regulated in a reversible fashion by mRNA-binding proteins.

Animals↗
PubMed1996

[Local vascular complications after iatrogenic femoral artery puncture].

Over a period of 5 years 81 vascular complications after 15,460 catheterizations of the femoral artery for diagnostic (n = 11,883) or therapeutic (n = 3577) procedures were registered. The following complications were observed in declining frequency: 1. False aneurysm (n = 65), 2. arterial occlusion (dissection, embolia, thrombosis) (n = 8), 3. vascular lesion causing profuse bleeding (n = 7), 4. AV-fistula (n = 1). The total complication rate was 0.52%. The complication rate was significantly higher in therapeutical procedures (1,03%) than in diagnostic investigations (0.37%). Pseudoaneurysms were complicated by thrombosis of the femoral vein (n = 3), lymphatic fistula (n = 3) and deep wound infection (n = 9); secondary complication rate 18.5%. Risk factors for local vascular complications are old age, female gender, high grade arteriosclerosis at the puncture site, overweight, manifest arterial hypertension and medication with cumarin, acetylsalicylic acid or heparin. Further complicating factors are connected with technical risks such as duration of the procedure. French size of the catheter, the catheter sheath and multiple punctures. Vascular repair was performed by simple angiography in most cases, but in 14.8% more extensive surgical procedures were required. In patients with signs of occlusive vascular disease the external iliac artery was replaced by a PTFE-vascular access graft in 4 cases and an arterioplasty of the deep femoral artery was performed in 2 patients. 36% of the operations were undertaken as emergencies. Reintervention was necessary for a postoperative bleeding complication in 1 case (surgical complication rate 1.2%). A female patient suffering from aortic valve stenosis died during emergency operation due to massive retroperitoneal hemorrhage after cardiac catheterization (mortality rate 1.2%). Over a median follow-up period of 37 months no late complications of the intervention were recorded, nor recurrences of peripheral arterial occlusive disease.

Aged↗
PubMed1996

Low density lipoprotein particle size and core cholesteryl ester physical state affect the proton NMR magnetic environment of fatty acid methylene and methyl nuclei.

Recent studies using proton NMR to quantify plasma lipoprotein concentrations have shown that lipoprotein particle size affects the chemical shift of methyl and methylene resonances. The purpose of this study was to investigate the interrelationship of low density lipoprotein (LDL) size and cholesteryl ester (CE) physical state on the chemical shift of methyl and methylene protons. LDL were isolated from the plasma of nonhuman primates fed diets containing lard or fish oil to result in a wide range of LDL particle sizes and CE core transition temperatures for NMR analysis. The proportion of nuclei in the fluid state in LDL at different temperatures, measured as proton NMR peak intensity, paralleled the melting profile of LDL CE determined by differential scanning calorimetry. At 37 degrees C the linewidths of several resolvable fatty acyl resonances, but not the choline methyl resonance, were significantly less in the fish oil LDL, indicating a less restrictive environment along the fatty acyl chain. The (CH2)n and t-CH3 resonances demonstrated an upfield shift (i.e., smaller chemical shift) with increasing temperature for both diet groups, but the peaks for fish oil LDL were always upfield from those of the lard LDL regardless of temperature. No change in the chemical shift of the choline CH3 resonance was observed as a function of dietary fat or temperature. Above the transition temperature for LDL CE there was a significant positive correlation between LDL size and the chemical shift of the (CH2)n and t-CH3 resonances. This relationship was not statistically significant for the same LDL below the Ce transition temperature. We conclude that LDL CE must be fully melted to obtain accurate results for LDL particle size distribution as well as mass quantification using portion NMR spectroscopy.

Animals↗
PubMed1996

A comparative study of sterol absorption in different small-intestinal brush border membrane models.

We reported previously that the absorption of cholesterol and long-chain cholesteryl esters by rabbit small-intestinal brush border membranes (BBMV) is protein-mediated (Thurnhofer, H., and H. Hauser. 1990. Biochemistry. 29:2142-2148; Compassi, S., M. Werder, D. Boffelli, F. E. Weber, H. Hauser, and G. Schulthess. 1995. Biochemistry. 34: 16473-16482). Evidence is presented for similar cholesterol transport activities in rabbit, pig, and human BBMV. As BBMV are subject to a number of limitations and the influence of these on sterol absorption is unknown, it is desirable to verify results obtained with this model system in other brush border membrane models more closely related to the in vivo situation. Sterol absorption in intact enterocytes parallels the absorption measured in BBMV, provided that both model systems are normalized to equal sucrase activity. The parallel behavior of the two brush border membrane models lends support to our previous conclusion that the brush border membrane takes up free and esterified cholesterol in a facilitated and energy-independent process. The absorption of sterols in small-intestinal segments mounted in the Ussing chamber is shown to be a complex process in which the diffusion of the bile salt micelles to the brush border membrane is rate-limiting. All brush border membrane models share the disadvantage of being unstable and subject to degradation. The seriousness of the problem increases apparently with the complexity of the model, i.e., in the order BBMV-->enterocytes-->intestinal segments. One main conclusion of this study is that no brush border membrane model is sufficient and satisfactory, therefore conclusive work in lipid absorption can never be based on a single brush border membrane model.

Absorption↗
PubMed1996

[Femoropopliteal vascular replacement: vein, ePTFE or ovine collagen?].

In an eight year-period from 1988 to 1995 653 femoropopliteal and femorocrural bypasses were performed. 347 above-knee reconstructions 206 below-knee reconstructions and at last 100 femorocrural bypasses were analysed. The cumulative patency rate after a follow up of three years for above-knee vein bypasses was 90%, patency rate for PTFE grafts in the same period was 52%, for ovine collagen grafts 56%. For below-knee bypasses with autologous saphenous vein a function rate of 76% could be observed in the same period, the rate of PTFE grafts in this position was only 30%. In this position 3-year patency rates of 50% were achieved with ovine collagen grafts. This difference was statistically significant. Three years cumulative patency rate for femorocrural reconstructions with greater saphenous vein was 72%, the function rate for PTFE in this position was below 30% after a follow up of one year, with ovine grafts below 40%. Graft infection, aneurysm formation and postoperative mortality were low in all groups. Our data demonstrate, that patency rates of autologous vein bypasses could not be achieved with PTFE or ovine collagen prosthesis in any femoropopliteal the femorocrural position. We therefore cannot confirm the recommendation to use alloplastic grafts as primary choice for above knee bypasses to spare the saphenous vein.

Adult↗
PubMed1995

Cholesteryl ester absorption by small intestinal brush border membrane is protein-mediated.

This paper provides unambiguous evidence that brush border membrane vesicles (BBMV) routinely prepared from rabbit small intestine contain a protein that catalyzes the absorption of long-chain cholesteryl ester and ether. The protein is located on the lumenal side of the brush border membrane. The experiments demonstrate that cholesteryl oleate need not be hydrolyzed prior to its incorporation in the BBMV. Unexpectedly and surprisingly, the absorption kinetics of free and esterified cholesterol are very similar in small intestinal BBMV using mixed bile salt micelles and small unilamellar phospholipid vesicles as the donor. The water-soluble form of the protein responsible for this effect is released into the supernatant, probably by autoproteolysis, and catalyzes the exchange of both free and esterified cholesterol between two populations of small unilamellar phospholipid vesicles (SUV). The water-soluble form of the protein was partially purified by a two-step procedure involving gel filtration on Sephadex G-75 and anion-exchange chromatography on Mono Q, yielding a 50-fold increase in the specific activity of the protein. The resulting protein gave two bands on sodium dodecyl sulfate--10% polyacrylamide gel electrophoresis and was used to raise polyclonal antibodies in sheep. The IgG fraction of the sheep antisera blocked the cholesteryl oleate and cholesterol exchange between two populations of SUV mediated by the antigen. The same IgG fraction produced a partial inhibition of cholesterol absorption in small intestinal BBMV. We conclude from the data presented that, contrary to the general belief prevailing in the field of lipid digestion and absorption, long-chain cholesteryl esters may be taken up by the brush border membrane as such and need not be hydrolyzed prior to absorption. The actual contribution of this mechanism to the total absorption of long-chain cholesteryl esters is probably limited by the low solubility of these compounds in mixed bile salt micelles and lipid vesicles.

Absorption↗
PubMed1995

The immunohistochemical localization of the non-specific lipid transfer protein (sterol carrier protein-2) in rat small intestine enterocytes.

A 13 kDa protein was isolated from rabbit small intestine brush-border membrane vesicles that was postulated to be involved in intestinal phosphatidylcholine (PC) and cholesterol uptake. This protein has cholesterol and PC-transfer activity in vitro (Turnhofer, H. et al. (1991) Biochim. Biophys. Acta 1064, 275-286) and has a molecular mass and isoelectric point similar to that of the non-specific lipid transfer protein (nsL-TP, identical to sterol carrier protein-2). In addition, the first 28 N-terminal amino acid residues of the 13 kDa protein are nearly identical to nsL-TP from different species (Lipka, G. et al. (1995) J. Biol. Chem. 270, 5917-5925). In view of its possible role in intestinal lipid absorption, the localization of nsL-TP in rat small intestine was investigated using immunohistochemistry and immunoblotting. It is shown that nsLTP is predominantly localized in a subapical zone of the enterocyte but not in the brush-border membrane, thereby excluding a role in lipid uptake of this protein at the level of the plasma membrane. nsL-TP co-localized with the peroxisomal marker PMP70, underscoring earlier observations that nsL-TP is a peroxisomal protein. nsL-TP was found to be present along the entire length of the small intestine. The 58 kDa cross-reactive protein that was recently identified as a peroxisomal thiolase was shown to be present only in a small segment approximately halfway down the jejunum. The close apposition of the peroxisomes with the apical membrane and the discrete distribution of the 58 kDa protein may indicate that these organelles play a role in the intracellular processing of absorbed lipids.

Amino Acid Sequence↗