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Biomedical subjects

M Bernhard

Publications and source records attributed to M Bernhard.

At least 37 records · Page 2Linked to original sources
PubMed2000

Ralstonia eutropha TF93 is blocked in tat-mediated protein export.

Ralstonia eutropha (formerly Alcaligenes eutrophus) TF93 is pleiotropically affected in the translocation of redox enzymes synthesized with an N-terminal signal peptide bearing a twin arginine (S/T-R-R-X-F-L-K) motif. Immunoblot analyses showed that the catalytic subunits of the membrane-bound [NiFe] hydrogenase (MBH) and the molybdenum cofactor-binding periplasmic nitrate reductase (Nap) are mislocalized to the cytoplasm and to the inner membrane, respectively. Moreover, physiological studies showed that the copper-containing nitrous oxide reductase (NosZ) was also not translocated to the periplasm in strain TF93. The cellular localization of enzymes exported by the general secretion system was unaffected. The translocation-arrested MBH and Nap proteins were enzymatically active, suggesting that twin-arginine signal peptide-dependent redox enzymes may have their cofactors inserted prior to transmembrane export. The periplasmic destination of MBH, Nap, and NosZ was restored by heterologous expression of Azotobacter chroococcum tatA mobilized into TF93. tatA encodes a bacterial Hcf106-like protein, a component of a novel protein transport system that has been characterized in thylakoids and shown to translocate folded proteins across the membrane.

Amino Acid Sequence↗
PubMed2000

[Anterior bridges with the IPS-Empress-2 System after alveolar ridge augmentation. A case report].

The success of a prosthesis is judged according to optimal function, good chewing comfort, adequate phonetics and white and pink esthetics. The aim of a treatment is to approach the perfection of nature. For anterior bridgework, the all-ceramic System IPS Empress 2 offers light transmission and reflection comparable to that of natural teeth, provided that the pink esthetics are optimised in the preprosthetic phase. The provision of an anterior bridge in the IPS Empress 2-system is presented here in the form of a case report. After extraction of the anterior teeth, a ridge augmentation including preparation of the pontic bed was carried out. The type of post and core, preparation and cementation are important parameters for the success of all-ceramic restorations.

Adult↗
PubMed1999

Reduced prostacyclin to thromboxane A2 ratio is correlated with central apneas in preterm infants.

Prostacyclin has a vasodilating effect on pulmonary vessels, whereas thromboxane A2 results in vasoconstriction. This study was designed to test the hypothesis that recurrent central apneas in preterm infants are correlated with a reduced prostacyclin to thromboxane A2 ratio. Twelve preterm infants with clinical events of apneas were matched with 12 control infants. Urinary concentration of 2,3-dinor-6-keto-PGF1alpha and 2,3-dinor-TxB2 was determined, and the ratio correlated with the number of central apneas (>20s) measured in overnight polygraphy. The number of central apneas >20s/12h was 97.4 (SE 7.8) in the study group, and 47.3 (SE 6.6) in the control group (p = 0.001). There was a significant correlation between the number of central apneas and the 2,3-dinor-6-keto-PGF1alpha/2,3-dinor-TxB2-ratio in all infants combined (r = -0.72, p < 0.0001) as well as in the two subject groups. Central apneas in premature infants are correlated with an decreased prostacyclin to thromboxane A2 ratio. The underlying pathomechanism may be increased intrapulmonary shunts with reflexive central apneas due to reduced pulmonary oxygenation.

6-Ketoprostaglandin F1 alpha↗
PubMed1998

The role of prophylactic antibiotics in spinal instrumentation. A rabbit model.

STUDY DESIGN: A rabbit model was used to test the efficacy of cefazolin administered in various therapeutic regimens in preventing iatrogenic Staphylococcus aureus infections during spinal instrumentation. OBJECTIVE: To assess the efficacy of various prophylactic therapeutic regimens of cefazolin in preventing iatrogenic S. aureus infections during spinal instrumentation. SUMMARY OF BACKGROUND DATA: Previous studies have not dealt specifically with the occurrence of iatrogenic S. aureus infections during spinal instrumentation in a prospective fashion. METHODS: Twenty New Zealand White rabbits underwent a posterior approach to the lumbar spine. Fifteen of the animals then had double-braided 26-gauge surgical wire placed around bilateral L3-L4 and L4-L5 facet joints. A standardized volume of a 103 S. aureus/mL of solution was then inoculated onto the fusion-hardware site in all rabbits. The rabbits were divided into four groups receiving various antibiotic dose regimens. Five days after surgery, the animals were killed, and cultures were obtained. RESULTS: All of the rabbits receiving no antibiotic had fusion sites infected with S. aureus. None of the animals who received prophylactic cefazolin produced cultures that grew S. aureus. A specimen from one fusion site cultured Staphylococcus epidermidis, which is not sensitive to cefazolin. Analysis of these data using Fisher's exact test resulted in a P value of 0.008 when results in antibiotic groups were compared with those in a group receiving no antibiotics and a P value of 0.0003 when all groups were compared. CONCLUSIONS: This model was valid and reproducible for the study of spinal instrumentation and infection. In addition, the data support the efficacy and use of prophylactic intravenous antibiotics in preventing infection in spinal instrumentation and fusion surgery.

Animals↗
PubMed1998

Different patterns of sighs in neonates and young infants.

To examine the prevalence and clinical assessment of sighs in neonates, we observed three different patterns of sighs: (A) sighs in the absence of apneic pause; (B) sighs with instantly following apneic pause >2 s, and (C) sighs with apneic pause >2 s following 1-3 normal breaths. We investigated preterm and term infants with 12 h nocturnal polygraphic recording. Sighs were more frequent in preterm than in term infants and more so during REM sleep than non-REM sleep. The part of sighs B of total number of sighs increased with gestational age. During REM sleep sighs without apnea were predominant, whereas apnea-associated sighs were mainly found during non-REM sleep.

Apnea↗
PubMed1997

Functional and structural role of the cytochrome b subunit of the membrane-bound hydrogenase complex of Alcaligenes eutrophus H16.

This study shows that the product of the hoxZ gene of Alcaligenes eutrophus H16 is a b-type cytochrome (cytochrome b(z)), which is essential for anchoring the membrane-bound hydrogenase (MBH) complex to the periplasmic side of the membrane and for H2-coupled respiration. The hoxZ product is not required for MBH translocation and H2-dependent reduction of the redox dye, 2,3,5-triphenyl-2-tetrazolium chloride. The lack of cytochrome b(z) does not affect the electron-transport activities linked to oxidation of succinate and NADH, although it enhances the electron-flow rate through the cytochrome-c oxidase pathway in hoxZdelta membranes. We show that the hoxZ product is a dihaem cytochrome b (haems with E(m7.0) of +10 mV and +166 mV) involved in H2-dependent electron transfer. We conclude that cytochrome b(z) of the A. eutrophus MBH complex is the link necessary for transfer of electrons from H2 to the ubiquinone pool and that it is required for attachment of MBH to the membrane.

Alcaligenes↗
PubMed1997

Bilateral breast carcinoma versus unilateral disease. Review of 498 patients.

In literature data, an uncertainty exists whether occurrence of bilateral breast cancer decreases the survival probability of affected patients. Therefore, we analyzed the medical records of 498 postoperatively irradiated (1977-1982) female breast cancer patients (T1-4,N0-3,M0). In the follow-up time, in 36 patients a bilateral breast carcinoma treated by surgery with or without radiotherapy was found. The 10-year overall survival rates were 54% in patients who had unilateral disease, compared with 56% in bilateral carcinoma patients, respectively. The incidence of metastasis did not differ between both groups: 24.2% versus 38.8%. Eleven percent of unilateral cancers recurred; in the other group, local failure of the first and second tumor was observed in 19.4% and 11.1%, respectively. We conclude that the occurrence of bilateral breast cancer has no significant impact on survival, although the development of local failures and metastases seems to be more frequent. The therapeutic strategy in bilateral carcinoma should resemble the treatment procedure in unilaterally affected patients.

Adult↗
PubMed1997

Insulin resistance with altered secretory kinetics and reduced proinsulin in cystic fibrosis patients.

BACKGROUND: Impaired glucose tolerance and secondary diabetes are frequent in older patients with cystic fibrosis (CF), associated with increased frequency of infections and reduced life expectancy. Studies on the pathophysiology of islet cell secretion in CF are a prerequisite for a scientifically based therapeutic approach. METHODS: Oral glucose tolerance tests were performed in 71 patients (14.2 +/- 0.5 years; mean +/- SE) and 56 control subjects (16.5 +/- 0.9 years). Glucose, insulin, C-peptide, and proinsulin were measured every 30 min. RESULTS: Glucose tolerance in CF patients was classified as normal (NGT, n = 48), impaired (IGT, n = 14), or diabetic (DM, n = 9). Even in CF patients with NGT, blood glucose was significantly elevated at 30, 60, and 90 min of the test. Surprisingly, the secretory responses of insulin and C-peptide were not reduced in CF patients with IGT or DM compared with both healthy controls or CF patients with normal glucose tolerance. However, peak insulin concentration was reached at 90 min in CF-IGT or CF-DM patients compared with 30 min in controls. The ratio of glucose to insulin, an indicator of insulin resistance, increased in CF patients with progression of carbohydrate intolerance. Proinsulin was significantly reduced in all CF patients compared with controls (p < 0.001; Wilcoxon's rank sum test). CONCLUSIONS: In CF patients with impaired glucose tolerance or diabetes, integrated insulin release is not diminished, indicating that insulin resistance is likely to contribute to hyperglycemia in CF patients with IGT or DM. Reduced proinsulin levels in CF patients are compatible either with enhanced conversion of proinsulin to insulin in compensation for reduced beta-cell mass, or enhanced clearance of proinsulin.

Adolescent↗
PubMed1996

The Alcaligenes eutrophus membrane-bound hydrogenase gene locus encodes functions involved in maturation and electron transport coupling.

Alcaligenes eutrophus H16 produces two [NiFe] hydrogenases which catalyze the oxidation of hydrogen and enable the organism to utilize H2 as the sole energy source. The genes (hoxK and hoxG) for the heterodimeric, membrane-bound hydrogenase (MBH) are located adjacent to a series of eight accessory genes (hoxZ, hoxM, hoxL, hoxO, hoxQ, hoxR, hoxT, and hoxV). In the present study, we generated a set of isogenic mutants with in-frame deletions in the two structural genes and in each of the eight accessory genes. The resulting mutants can be grouped into two classes on the basis of the H2-oxidizing activity of the MBH. Class I mutants (hoxKdelta, hoxGdelta, hoxMdelta, hoxOdelta, and hoxQdelta) were totally devoid of MBH-mediated, H2-oxidizing activity. The hoxM deletion strain was the only mutant in our collection which was completely blocked in carboxy-terminal processing of large subunit HoxG, indicating that hoxM encodes a specific protease. Class II mutants (hoxZdelta, hoxLdelta, hoxRdelta, hoxTdelta, and hoxVdelta) contained residual amounts of MBH activity in the membrane fraction of the extracts. Immunochemical analysis and 63Ni incorporation experiments revealed that the mutations affect various steps in MBH maturation. A lesion in hoxZ led to the production of a soluble MBH which was highly active with redox dye.

Alcaligenes↗
PubMed1996

Carboxyl-terminal processing of the cytoplasmic NAD-reducing hydrogenase of Alcaligenes eutrophus requires the hoxW gene product.

Two open reading frames (ORFs) were identified immediately downstream of the four structural genes for the soluble hydrogenase (SH) of Alcaligenes eutrophus H16. While a mutation in ORF2 had no obvious effect on hydrogen metabolism, an in-frame deletion in ORF1, subsequently designated hoxW, led to a complete loss of SH activity and hence a significant retardation of autotrophic growth on hydrogen. Hydrogen oxidation in the hoxW mutant was catalyzed by the second hydrogenase, a membrane-bound enzyme. Assembly of the four subunits of the SH was blocked in mutant cells, and HoxH, the hydrogen-activating subunit, accumulated as a precursor which was still capable of binding nickel. Protein sequencing revealed that HoxH isolated from the wild type terminates at His-464, whereas the C-terminal amino acid sequence of HoxH from the hoxW mutant is colinear with the deduced sequence. Processing of the HoxH precursor was restored in vitro by a cell extract containing HoxW. These results indicate that HoxW is a highly specific carboxyl-terminal protease which releases a 24-amino-acid peptide from HoxH prior to progression of subunit assembly.

Alcaligenes↗
PubMed1991

Comparative study of mercury accumulation in dolphins (Stenella coeruleoalba) from French Atlantic and Mediterranean coasts.

Total mercury concentrations (Hgt) have been determined in liver, kidneys, skeletal muscle, melon, stomach and intestine of 35 specimens of Stenella coeruleoalba stranded on French Atlantic and Mediterranean coasts. Very high mercury levels, with concentrations reaching 80 mg Hgt kg(-1) fresh weight (FW) in muscle and about 1500 mg Hgt kg(-1) FW in liver tissue, were observed. Liver has the highest concentration, followed by muscle and kidney. The lowest concentrations were found in the melon. The levels observed in the Mediterranean specimens are among the highest observed in marine organisms and confirm previous reports of high mercury levels in marine mammals from the Mediterranean. Comparison between Hgt accumulation levels in these two geographic groups of dolphins shows that Mediterranean individuals have much higher concentrations than specimens from the Atlantic. These differences provide additional confirmation for the higher Hgt concentrations observed previously in other pelagic species (tuna, sardine, anchovy, etc.) from the Mediterranean Sea. Taking into consideration the pelagic habitat of the dolphin and the local influence of anthropogenic mercury sources it seems reasonable to assume that the main source of the high mercury concentrations observed in Mediterranean biota is natural mercury deposits located in many regions of the Mediterranean basin.

Animals↗
PubMed1987

Total mercury, organic mercury, copper, manganese, selenium, and zinc in Sarda sarda from the Gulf of Genoa.

The total mercury content of the Atlantic bonito (Sarda sarda) increases with increasing size of the specimen, as shown by other authors for other marine organisms (Renzoni et al., 1973; Buffoni et al., 1982; Bernhard and Andreae, 1984; Thibaud, 1986). Organic mercury content also increases with the size of the specimen, whereas inorganic mercury remains constant, which is in agreement with the prediction made on another species of Sgombridae (Bernhard, 1985). This kind of mercury partitioning has not, to our knowledge, been reported for other species of fish. It is interesting to note that the mercury concentration in the gonads also increases with the size of the specimen. A very small difference between the total mercury content of white and dark muscle was observed, while for selenium, zinc, copper, and manganese the concentrations are lower in white muscle than in dark muscle.

Animals↗
PubMed1987

[Status of radiologic pelvimetry].

The diagnostic value of radiological pelvimetry is subject to controversial interpretation. This examination is being conducted at the Department of Gynaecology in Aarau (Frauenklinik Aarau) mainly in pregnant women in pelvic presentation or during the puerperium after Caesarean section. Based on 164 radiological pelvimetric measurements in breech presentation and 112 X-ray films after Caesarean section an attempt was made to assess the prospective value of this examination. Abnormal shapes of the pelvis and narrow pelvic dimensions were found about equally often. Analysis of the indications of the section yielded both in breech presentation and in the entire group of the patients examined post partum an almost equally high percentage of about 20% of indications for a disproportionate head-pelvis relationship. Radiologically, considerably narrowed pelvic dimensions were seen in 10% of the examined women. The most frequent finding was a funnel-shaped pelvis, whereas an assimilation pelvis was never seen. Every pathologically narrowed funnel-shaped pelvis and generally narrow pelvis was detected also by digital palpation. All cases of conjugata vera masses below 10 cm concerned generally narrow cases of pelvic dimensions and were thus detectable by digital palpation. We recommended to abstain from routine performance of radiometric pelvimetry. Lateral pelvic X-ray can be an additional help in difficulties in pregnant women with regard to determining the mode of birth in breech presentation and after Caesarean section in case there is an urgent suspicion of malproportionate head-pelvis ratios.

Cesarean Section↗
PubMed1979

[Panoramic radiography: why the controversy?].

Because of the confusion which exists between the panography and the orthopantomogram we like to rectify the error. With the orthopantomograph the mandible and the maxilla are taken on a single film. The radiation source is extraoral, whereas for a panography the radiation source is directed from the oral cavity towards the outside, two films are needed, one for each jaw. The orthopantomogram can be used generally in odonto-stomatology. Dosimetry was also mentioned. The results prove that for an orthopantomogram the radiation dose is four times smaller than the dose given for full mouth X-rays taken with 16 intraoral films. It appears that an orthopantomogram should be the first step for a general X-ray examination, though it does not give all informations. For details the intraoral film keeps its value.

Humans↗
PubMed1977

Panoramic radiography in the examination of edentulous patients.

A radiologic survey covering 4 years and using orthopantomography was made of 287 edentulous patients prior to denture construction. Orthopantomographs revealed 155 significant lesions in 41 per cent of the patients examined. Therefore, the use of panoramic radiography before any prosthetic procedure is undertaken seems justified. Surgery would be indicated where cysts (residual and follicular), visible root fragments, and sequestra are detected. In most situations, such as deeply imbedded impactions, localized sclerotic bone, or foreign bodies, surgery would not be justified for elderly patients because of the possible unfavorable aftereffects. When this decision is made, the patient should be informed of the possibility of future surgical and prosthetic procedures.

Alveolar Process↗