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Biomedical subjects

H Visser

Publications and source records attributed to H Visser.

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

An anthropomorphic phantom for periodontal radiography.

OBJECTIVE: To construct an anthropomorphic phantom for periodontal radiography. METHODS: The phantom material for the spongiosa was produced by melting polyethylene with calcium hydroxyapatite. Compact bone and teeth were simulated by mixing silicone rubber with calcium hydroxyapatite and calcium carbonate respectively. RESULTS: Radiographs of the phantom show nearly all the structures relevant for periodontal radiography. Measurements of X-ray attenuation and optical density correspond to those of the human mandible. Any defect in the periodontal bone can be reproduced. CONCLUSION: The new phantom will be useful for research and education.

Alveolar Bone Loss↗
PubMed1995

[Strong increase in unmarried couples: some main results from the Annual Household Statistics, 1988-1994].

"The [Netherlands] Annual Household Statistics are based on the Labour Force Survey. Since 1988 the main trends show an increase of not-married couples who live together (with or without children), an increase of married couples without children and an increase of one-person households. Households consisting of married couples with children are on the decrease." (SUMMARY IN ENG)

Demography↗
PubMed1994

[Children become adults].

"The 1993 Netherlands Fertility and Family Survey interviewed about 3,700 men and 4,500 women in the age-group of 18 to 43 years. Amongst others, information was collected with respect to leaving the parental home.... Based on the collected information three groups of home leavers can be distinguished. The first group consists of children who leave their parents at a relatively young age.... Secondly a group [of] home leavers can be distinguished who leave at a relatively old age (and some of them so far never did).... The third group which can be distinguished consists of children who leave their parents at an age at which about most of the children leave." (SUMMARY IN ENG)

Age Factors↗
PubMed1994

[High-frequency dental surgery near metal reconstructions].

Dental electrosurgery carries the risk of incidental contact between the active electrode and metallic restorations. So far, on-line measurements of basic physical parameters during dental electrosurgery have not been performed under realistic conditions. The aim of our experimental study in pig jaws was to describe the physical phenomena more closely. 86 teeth in the jaws of freshly slaughtered pigs received occlusal amalgam fillings. Using 3 different units electrosurgical procedures were performed adjacent to the fillings. Voltage, current, impedance and power output were registered using a computer-controlled measuring system with high temporal resolution and broad dynamic range. The impedances of the amalgam fillings ranged from 0.5 to 9 k omega, with half of them being in the lower range of 0.5 to 1.5 k omega. During contact to amalgam fillings the dental electrosurgical unit had a high power output. Contact to fillings with low impedance yielded a power output up to 50 W. The other two electrosurgical units were equipped with different power output control systems thus preventing high power output during contact to metallic restorations. In conclusion, dental electrosurgery should be improved by units with dynamic power output control.

Animals↗
PubMed1993

Histology of laser- and high-frequency-electrosurgical incisions in the palate of pigs.

The histological effects of CO2-laser-, Nd-YAG-laser- and electrosurgical incisions were investigated in the oral mucosa of pigs. Laser- as well as electrosurgery caused necrosis by thermal effects. Undermining vacuolisation in the stratum basale and denaturation of collagenous fibers in the lamina propria were typical findings. The CO2-laser incisions were trough-like with a sharply bordered coagulation. The Nd-YAG-laser produced exclusively coagulation but no incision. Electrosurgery yielded radiating coagulation and the best ratio of depth of incision to width of coagulation.

Aluminum Silicates↗
PubMed1993

Cloning, nucleotide sequence, and regulatory analysis of the Lactococcus lactis dnaJ gene.

The dnaJ gene of Lactococcus lactis was isolated from a genomic library of L. lactis NIZO R5 and cloned into pUC19. Nucleotide sequencing revealed an open reading frame of 1,137 bp in length, encoding a protein of 379 amino acids. The deduced amino acid sequence showed homology to the DnaJ proteins of Escherichia coli, Mycobacterium tuberculosis, Bacillus subtilis, and Clostridium acetobutylicum. The level of the dnaJ monocistronic mRNA increased approximately threefold after heat shock. The transcription initiation site of the dnaJ gene was determined and appeared to be preceded by a typical gram-positive vegetative promoter sequence (TTGCCA-17 bp-TAAAAT). Upstream of the promoter region, an inverted repeat is located that is identical to those detected upstream of heat shock genes of other gram-positive organisms. A transcriptional fusion between the dnaJ expression signals and a usp45-amyS secretion cassette caused a significant increase in alpha-amylase activity after heat shock induction. Deletion mutagenesis showed that the inverted repeat is involved in heat shock regulation of the dnaJ gene. The conservation of this palindromic sequence in gram-positive heat shock genes suggests a common regulatory pathway distinct from the system used in gram-negative bacteria.

Amino Acid Sequence↗
PubMed1993

[National household forecasts 1993].

Revised household population forecasts for the Netherlands are presented for 1993, based on recent data from the Annual Household Statistics. "According to the 1993 household forecasts the number of households will increase from 6.2 million in 1992 to 7.3 million in 2010. The main source of the increase is the rise of the number of one-person households from 1.9 million to 2.7 million. As a result the number of households will increase more strongly than population size. Whereas population size in 2010 will be 11% higher than in 1992, the number of households will rise by 17%." (SUMMARY IN ENG)

Developed Countries↗
PubMed1993

Antineutrophil cytoplasm antibodies in systemic polyarteritis nodosa with and without hepatitis B virus infection and Churg-Strauss syndrome--62 patients.

OBJECTIVE: Antibodies directed against components of neutrophil cytoplasm have been detected in various systemic vasculitides and especially in Wegener's granulomatosis. In polyarteritis nodosa (PAN) and Churg-Strauss syndrome, few data are available and correlation between clinical manifestations and antineutrophil cytoplasm antibodies (ANCA) has not been established. Therefore, we tested, before treatment of vasculitis, 62 consecutive patients suffering from PAN with hepatitis B virus (HBV) markers, PAN of unknown etiology or Churg-Strauss syndrome. METHODS: Only patients with PAN and Churg-Strauss syndrome were included in the study. The diseases were histologically and/or angiographically proven. Every patient's serum was tested by an indirect immunofluorescence assay (IFA) and, in 37 cases, by an enzyme linked immunosorbent assay (ELISA). RESULTS: ANCA detected by IFA were observed in 10.7% of the patients with PAN with HBV markers, in 27.3% of the patients with PAN without HBV markers and in 66.7% of the patients with Churg-Strauss syndrome. When ELISA was performed, 11.1% of the patients with PAN associated with HBV infection, 20% of the patients with PAN without HBV markers and 55.6% of the patients with Churg-Strauss syndrome were positive. ANCA were positively correlated with asthma and purpura and negatively correlated with HBV markers. CONCLUSION: Regardless of the technique used, Churg-Strauss syndrome was associated with ANCA in about 60% of the cases while, in PAN of unknown etiology, ANCA were found in about 25% of cases. In contrast, IFA and ELISA only detected ANCA in a limited number of cases of PAN related to HBV infection. ELISA positivity in patients with PAN and Churg-Strauss syndrome was usually associated with antimyeloperoxidase antibodies. In our cases of PAN, ANCA and purpura were significantly correlated, suggesting that, in these cases, small vessels are involved and therefore macroscopic and microscopic PAN coexist. Thus it seems that ANCA are essentially present in the cases of small vessel vasculitis, as has been described, and are not a marker of pure macroscopic PAN, at least at our present level of understanding of these antibodies.

Adult↗
PubMed1992

Binding of surfactant protein A (SP-A) to herpes simplex virus type 1-infected cells is mediated by the carbohydrate moiety of SP-A.

Pulmonary surfactant protein A (SP-A) has been shown to act as an opsonin in the phagocytosis of viruses by alveolar macrophages. To determine whether SP-A binds to viral proteins and which part of the SP-A molecule is involved in this interaction, binding studies were undertaken. SP-A was labeled with fluorescein isothiocyanate, and its binding to herpes simplex virus type 1-infected HEp-2 cells, as a model for virus-infected cells in general, was studied using flow cytometry. The binding of SP-A to virus-infected cells was saturable, reversible, and both time- and concentration-dependent, reaching a maximal level after 30 min at an SP-A concentration of 10 micrograms/ml. An approximately 4-fold increase in binding of SP-A to infected cells over control cells was observed. Yeast mannan, a mannose homopolysaccharide, did not influence the binding. However, heparin inhibited binding of SP-A in a concentration-dependent manner. In addition, heparin could also dissociate cell-bound SP-A, indicating that polyanionic oligosaccharides are involved in the binding of SP-A to virus-infected cells. Deglycosylated SP-A, obtained by digestion with N-glycosidase F, did not bind to infected cells. Heparin or deglycosylation of SP-A had no effect on the stimulation of alveolar macrophages by SP-A. It is concluded that the carbohydrate moiety of SP-A is involved in the recognition of viruses by SP-A and may play a role in the antiviral defenses of the lung.

Animals↗
PubMed1991

[A prospective study on the incidence of mercury levels in dental students. 2. Correlation analysis].

The urinary mercury levels of 49 dental students have been examined in a longitudinal study for one year. The correlation of the measured values with the number of amalgam fillings, age, sex, smoking habits, and nutrition was assessed. The urinary mercury levels did not correlate with sex and smoking habits, but there was a correlation with the number of amalgam fillings. The data obtained in our longitudinal study confirm the results of cross sectional studies: amalgam fillings contribute a measurable though small amount to urinary mercury excretion.

Adult↗
PubMed1991

[Measurement of physical parameters in HF surgical techniques in dentistry].

A method for measuring electrical parameters in dental electrosurgery and new data on this surgical technique are presented. A computer-controlled system which measures voltage, current, phase, power and impedance with high temporal resolution was applied to dentistry. Statistical analysis of many operations on freshly butchered pig jaws was performed. The impedance of oral soft tissues is higher during cutting, the power required smaller than stated in the literature. The influence of frequency, power-output control, anatomical structures, and metallic restorations on dental electrosurgery is discussed in detail.

Animals↗
PubMed1991

[Recommendations for training with dental HF surgery apparatus].

A training program for the application of dental electrosurgery is presented. Exercises on muscle tissue and pig jaws are suitable to get informations of the proper adjustment of the units as well as the treatment procedures. The necessity of proper handling is illustrated by the results of wrong manipulations. Better understanding of the facts during electrosurgery enables the dentist to avoid adverse effects in treating his patients.

Animals↗