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Biomedical subjects

H Blessing

Publications and source records attributed to H Blessing.

At least 19 recordsLinked to original sources
PubMed2005

Tissue engineering of bone: effects of mechanical strain on osteoblastic cells in type I collagen matrices.

The aim of the present study was to investigate the effect of cyclic uniaxial mechanical strain on a human osteoblastic precursor cell line (hFOB 1.19) in three-dimensional type I collagen matrices. Cell seeded collagen constructs were mechanically stretched by a daily application of cyclic uniaxial strain using a special motor-driven apparatus and compared to unstretched controls. Expression of genes involved in cell proliferation and osteoblastic differentiation as well as matrix production were investigated by analyzing the mRNA of histone H4, core binding factor 1, alkaline phosphatase, osteopontin, osteocalcin, and collagen type I (Col I) up to a cultivation period of 3 weeks using real-time PCR. Cyclic stretching of cell seeded Col I matrices at a magnitude occurring in healing bone increased cell proliferation and slightly elevated the expression of nearly all investigated genes over unstrained controls at various time points. It was concluded that mechanical load promotes the proliferation and differentiation of osteoblastic precursor cells in a Col I matrix and that the application of mechanical stimuli may have a beneficial effect on in vitro tissue formation.

Biocompatible Materials↗
PubMed2004

[Effects of mechanical strain on human osteoblastic precursor cells in type I collagen matrices].

BACKGROUND: The aim of the present study was to investigate the effect of mechanical strain on human osteoblastic precursor cells in a three-dimensional scaffold. METHODS: Osteoblastic precursor cells were seeded in a collagen type I gel and mechanically stretched by daily application of cyclic uniaxial strain. The expression of histone H4, core binding factor 1, alkaline phosphatase, osteopontin, osteocalcin, and collagen type I was investigated by analysing the mRNA. Cell and matrix orientation were investigated by scanning electron microscopy. RESULTS: Cyclic stretching increased cell proliferation. The expression of osteogenic markers was slightly increased by mechanical strain. The cells and matrix were strictly oriented in the stress direction. CONCLUSION: The application of mechanical load might have a beneficial effect on the quality and quantity of generated bone tissue and might be a important factor in tissue engineering of bone.

Alkaline Phosphatase↗
PubMed2003

Modulation of DNA repair processes by arsenic and selenium compounds.

Nickel, cadmium, cobalt and arsenic compounds are well known carcinogens to humans and experimental animals. In addition to the induction of mainly oxidative DNA damage, they interfere with nucleotide and base excision repair (BER) at low, non-cytotoxic concentrations. In case of arsenic, an inactivation of DNA repair has also been observed for the trivalent and pentavalent methylated metabolites, with the strongest effects exerted by MMA(III) and DMA(III). As potential molecular targets, interactions with so-called zinc finger proteins involved in DNA repair and/or DNA damage signaling have been identified. For example, arsenite suppresses poly(ADP-ribosyl)ation at extremely low, environmentally relevant concentrations. Also, Fpg and XPA involved in BER and NER, respectively, are inactivated by arsenite, MMA(III) and DMA(III). Nevertheless, an interaction with the zinc finger structures of DNA repair proteins may also occur by essential trace elements such as certain selenium compounds, which appear to exert anticarcinogenic properties at low concentrations but may compromise genetic stability at higher concentrations.

Animals↗
PubMed2002

Interference by toxic metal ions with zinc-dependent proteins involved in maintaining genomic stability.

Metal ions are essential components of biological systems; nevertheless, even essential elements may have toxic or carcinogenic properties. Thus, besides As(III) and Cd(II), also Ni(II) and Co(II) have been shown previously to disturb different types of DNA repair systems at low, non-cytotoxic concentrations. Since some metals exert high affinities for SH groups, we investigated whether zinc finger structures in DNA-binding motifs of DNA repair proteins are potential targets for toxic metal ions. The bacterial formamidopyrimidine-DNA glycosylase (Fpg protein) involved in base excision repair was inhibited by Cd(II), Cu(II) and Hg(II) with increasing efficiencies, whereas Co(II), As(III), Pb(II) and Ni(II) had no effect. Furthermore, Cd(II) still disturbed enzyme function when bound to metallothionein. Strong inhibition was also observed in the presence of phenylselenyl chloride, followed by selenocystine, while selenomethionine was not inhibitory. Regarding the mammalian XPA protein involved in the recognition of DNA lesions during nucleotide excision repair, its DNA-binding capacity was diminished by Cd(II), Cu(II), Ni(II) and Co(II), while Hg(II), Pb(II) and As(III) were ineffective. Finally, the H(2)O(2)-induced activation of the poly(ADP-ribose)polymerase (PARP) involved in DNA strand break detection and apoptosis was greatly reduced by Cd(II), Co(II), Ni(II) and As(III). Similarly, the disruption of correct p53 folding and DNA binding by Cd(II), Ni(II) and Co(II) has been shown by other authors. Therefore, zinc-dependent proteins involved in DNA repair and cell-cycle control may represent sensitive targets for some toxic metals such as Cd(II), Ni(II), Co(II) and Cu(II), as well as for some selenium compounds. Relevant mechanisms of inhibition appear to be the displacement of zinc by other transition metals as well as redox reactions leading to thiol/disulfide interchange.

Cations, Divalent↗
PubMed2002

Identification of glycoprotein gpTRL10 as a structural component of human cytomegalovirus.

Human cytomegalovirus (HCMV) has a coding capacity for glycoproteins which far exceeds that of other herpesviruses. Few of these proteins have been characterized. We have investigated the gene product(s) of reading frame 10, which is present in both the internal and terminal repeat regions of HCMV strain AD169 and only once in clinical isolates. The putative protein product is a 171-amino-acid glycoprotein with a theoretical mass of 20.5 kDa. We characterized the protein encoded by this reading frame in the laboratory strain AD169 and a recent isolate, TB40E. The results from both strains were comparable. Northern blot analyses showed that the gene was transcribed with early/late kinetics. Two proteins of 22 and 23.5-kDa were detected in virus-infected cells and in cells transiently expressing recombinant TRL10. Both forms contained only high-mannose-linked carbohydrate modifications. In addition, virus-infected cells expressed small amounts of the protein modified with complex N-linked sugars. Image analysis localized transiently expressed TRL10 to the endoplasmic reticulum. Immunoblot analyses as well as immunoelectron microscopy of purified virions demonstrated that TRL10 represents a structural component of the virus particle. Immunoblot analysis in the absence of reducing agents indicated that TRL10, like the other HCMV envelope glycoproteins, is present in a disulfide-linked complex. Sequence analysis of the TRL10 coding region in nine low-passage clinical isolates revealed strain-specific variation. In summary, the protein product of the TRL10 open reading frame represents a novel structural glycoprotein of HCMV and was termed gpTRL10.

Amino Acid Sequence↗
PubMed2000

[Is appendectomy really performed too frequently? Results of the prospective multicenter study of the Swiss Society of General Surgery].

Scientific publications and provoking criticism from the lay press have recently pointed out, that appendices may be surgically removed too frequent and without indisputable necessity. In an attempt to verify these questionable statements, the Swiss Society for General Surgery (SGAC) initiated a prospective controlled multi center trial. From September 1997 to December 1998, hundred and twenty-five institutions documented 4603 appendectomies performed due to a suspected appendicitis. Histological investigation of all specimens revealed a 7% rate of normal appendices, 7.2% for patients with national health service (NHS) and 5.9% for patients with private insurances respectively. Compared to the results of the literature, where a frequency of normal appendices around 15% is judged as standard, these results are excellent. In 17.2% of the patients (15.9% NHS and 23.6% privately insured patients) an "appendicitis perforata" was observed. This percentage remains in the range reported by other authors. The analysis of time of admission (i.e. day or night) and the delay from admission to surgery shows a distribution independent to the insurance of the patients. Therefore, the planned appendectomy for patients with private insurances does not exist. A different choice of the surgical technique could be observed depending on the insurance status. In 30.4% of the private insured patients a laparoscopic appendectomy was performed as compared to 22.6% of patients with NHS. Surprisingly, an identical median hospitalization time can be observed for both groups (laparoscopic 5.5 days, open surgery 5.5 days).

Adolescent↗
PubMed2000

Catechol-O-methyltransferase inhibition attenuates levodopa toxicity in mesencephalic dopamine neurons.

Inhibition of catechol-O-methyltransferase (COMT; EC 2.1.1.6) is a new therapeutic strategy in the treatment of Parkinson's disease. However, nothing is known about the effects of COMT inhibition on levodopa (L-dopa)-induced toxicity in dopamine (DA) neurons. Therefore we evaluated the effects of the selective COMT inhibitors Ro 41-0960, OR-486, and tolcapone alone and in combination with L-dopa in primary mesencephalic cultures from rat. Neither COMT inhibitor affected the growth of tyrosine hydroxylase immunoreactive (THir) cells with concentrations up to 10 microM when studied alone. However, Ro 41-0960 reduced the L-dopa-induced THir cell loss after 24 h in a dose-dependent manner, shifting the TD(50) value from 21 microM in the absence to 71 microM in the presence of 1 microM Ro 41-0960 (P <.01) without affecting survival of non-DA neurons. OR-486 and the clinically used COMT inhibitor tolcapone showed similar effects. In contrast, toxicity induced by D-dopa was not altered by COMT inhibitors. Furthermore, the primary metabolite of L-dopa formed by COMT, 3-O-methyldopa, and the methyl group donor S-adenosyl-L-methionine used by COMT did not alter THir neuron survival and L-dopa-induced toxicity, respectively, with concentrations up to 100 microM. These data demonstrate that COMT inhibition attenuates L-dopa toxicity toward DA neurons in vitro, but probably not by preventing 3-O-methyldopa production or cellular S-adenosyl-L-methionine depletion.

Animals↗
PubMed1997

[Leiomyosarcoma of the small intestine].

Leiomyosarcomas of the small bowel are quite rare. These tumors are mostly located in the jejunum distal of the duodeno-jejunal flexure. The non-metastasizing leiomyosarcomas have a good prognosis, according to the literature. The adequate surgical treatment is the resection of the small bowel. Chemotherapy is discussed if there is evidence of metastatic disease. For the diagnosis of leiomyosarcomas tumor markers have no significance. We report the case of a 79 years old patient with a leiomyosarcoma of the jejunum who was admitted as an emergency with an acute abdomen and underlying chronic anaemia. This case demonstrates the often unspecific symptoms and characteristics of leiomyosarcomas.

Aged↗
PubMed1997

[The LAPARO-HOOK for use in gas-free laparoscopy].

This report describes our newly developed retractor, the LAPARO-HOOK, for gasless laparoscopy. Compared to other systems it is less traumatic and easy to handle. The abdominal working space is similar to the one using a pneumoperitoneum. A further advantage, especially in the learning-phase, is the possibility to convert to traditional laparoscopy by insufflating CO2 at any time.

Carbon Dioxide↗
PubMed1997

[Endoscopic pre-peritoneal prolene mesh-plasty for management of inguinal and femoral hernias].

From October 1994 to March 1996 158 inguinal or femoral hernias were repaired in 124 patients through a total extraperitoneal approach. The repairs were done with polypropylene mesh. The patients were seen 6 to 8 weeks postop; until today 57 patients were seen 12 months postop. This method favours an early return to work. Patients with unilateral hernias returned to work after an average of 14 days, patients with bilateral hernias after an average of 19 days. Complications were rare and mostly minor. So far we have seen no recurrences and no mesh related complications. We consider the laparoscopic extraperitoneal mesh repair a safe procedure for inguinal and femoral hernias.

Adult↗
PubMed1996

[Surgical therapy of anal fissure].

Lateral internal sphincterotomy has shown to be a very efficient method to treat acute and especially chronic anal fissure. The question remains, whether it is possible to optimate the short and long term outcome by individualizing the extent of sphincterotomy. This can be done by calculating the length of the anal canal and the area under the curve on a preoperative manometric pressure profile. We present the short and long term results over 3 years in a consecutive series of 30 anal fissures. All patients remained symptomfree and had full anal sphincter competence.

Adult↗
PubMed1996

[Laparoscopic endoscopic pre-peritoneal combined hernia operation in incarcerated indirect inguinal hernia].

We report on a 73-year-old patient with an incarcerated right sided groin hernia. First the incarcerated small bowel was gently retracted laparoscopically; then using the extraperitoneal endoscopic approach the hernial sack was redused and a 15/13 cm prosthesis (polypropylene mesh) brought in appropriate position and fixed with endo-staples. Prior to closing the trocar-incisions the vitality of the small bowel was checked once again laparoscopically.

Aged↗
PubMed1993

[Late results after individualized lateral internal sphincterotomy].

A total of 75 patients underwent individualized lateral internal sphincterotomy for acute and chronic anal fissure (n = 30) or high pressure hemorrhoids (n = 45) and were followed-up 3 months and 3 years (13-66 months) postoperatively. All but one patient with anal fissure (97%) and 38 out of 45 patients with hemorrhoids (84%) remained symptom free; only one patient (1.3%) occasionally had symptoms of minor incontinence. Following the operation both the maximum resting pressure and the medium anal pressure fell significantly and were completely or nearly normalized in 54 (72%) and 17 (23%) patients respectively. At medium follow-up of 3 months and 3 years postoperatively there was no significant difference in the two sets of postoperative manometric results.

Adult↗
PubMed1992

[Chronic pancreatitis of the head of the pancreas in hyperplasia of the body and tail of the pancreas].

We report a case of chronic pancreatitis of the head of the pancreas complicated with insulin-requiring diabetes mellitus, in a 44-year-old woman with hypoplasia of the dorsal pancreas. Preoperative ultrasonography, computerized tomography and angiography revealed a calcifying retroperitoneal mass, which on explorative laparotomy proved to be a severe chronic pancreatitis of the head of the pancreas with a finding of abnormal visibility of the confluens venosum and absence of both the corpus and the tail of the pancreas. The postoperative course following pylorus-preserving duodenopancreatectomy was uneventful.

Adult↗
PubMed1989

[Spontaneous vaginal rupture with prolapse of the small intestine].

Spontaneous rupture of the vaginal vault is a rare event. Patients at risk are postmenopausal. Very often they show symptoms of an enterocele or have been operated before vaginally. Treatment is always by surgery. Whether it can be done vaginally or by laparotomy, depends on the local situation. To prevent recurrence, a double closure of the lesion is necessary, often combined with colpocleisis, colpectomy, sacropexie or obliteration of the "cul-de-sac".

Aged↗
PubMed1989

[Initial experiences with a new kind of computer compatible coding and analysis system for inpatient and ambulatory services].

This paper describes a new concept of an operational database management system including the word processing program "Word Star". The system structure is composed of patients identities and linked MIR's (medical information records) to follow a patient's history in space and time. In- and out-patient's data are collected on a special data sheet with numeric responses from the following areas: demographics including risk factors, diagnosis, surgical procedure, intra- and postoperative morbidity analysis. Data are entered using a DBS-16 concurrent dos system and stored on a 105 Megabytes hard disk. The software program in its compiled version allows for processes like outpatients clinic management, appointments organisation and statistical analysis of different variables thus providing detailed information on patients postoperative morbidity.

Ambulatory Care↗