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Biomedical subjects

R Koch

Publications and source records attributed to R Koch.

At least 127 records · Page 7Linked to original sources
PubMed1997

An intronic germline transition in the HNPCC gene hMSH2 is associated with sporadic colorectal cancer.

The aim of this study was to determine whether an intronic germline substitution in the hereditary non-polyposis colorectal cancer (HNPCC) gene hMSH2 represents a genetic risk factor for sporadic CRC. Possible effects of this substitution were investigated by assessment of microsatellite instability and hMSH2 cDNA sequencing. Constitutional DNA from patients with sporadic CRC and healthy controls from the same region in Germany was analysed for the intronic germline T-->C transition six bases upstream of exon 13 of hMSH2. 29 of 106 patients (27%) were found to harbour the germline T-->C transition as opposed to only 13 of 125 controls (10%; P < 0.001; OR 3.2, CI 1.58-6.63). CRCs from patients with the substitution displayed neither clinical HNPCC-like features nor an increased rate of microsatellite instability. No abnormal cDNA sequence was found at the exon 12-13 border. These data suggest a 3.2-fold increased risk of sporadic CRC for individuals with the intronic hMSH2 transition. However, this substitution might not be pathogenic itself, but may be linked to a locus nearby that is.

Adult↗
PubMed1997

[DIMA-magnification mammography. Phantom studies on image quality and radiation exposure of the patient].

PURPOSE: A mammographic system has been developed to provide direct radiographic magnification; investigation of image quality and radiation exposure for surveys and aimed exposures were carried out on phantoms and the results compared with two modern screen methods. MATERIAL AND METHOD: Image quality was defined by contrast transfer function, resolution of low contrast, contrast of large areas and recognition of low contrast detail, using suitable phantoms. Measurements of entrance surface dose were made with a 1 cm3 flat chamber. RESULTS: For survey examinations, the new mammographic system provided image quality equal to a screen system but using 50% radiation dose. For localised views, the new system used similar radiation dose but provided significantly better demonstration of diagnostic detail. CONCLUSION: Using a focal spot of 40-120 microns, the new mammographic system provides markedly improved direct radiographic magnification. With reduced radiation exposure at times, there is a significant gain in diagnostic information compared with current standard systems.

Female↗
PubMed1997

Purification and Properties of a Thermostable Pullulanase from a Newly Isolated Thermophilic Anaerobic Bacterium, Fervidobacterium pennavorans Ven5.

Extremely thermophilic anaerobic fermentative bacteria growing at temperatures between 50 and 80(deg)C (optimum, 65 to 70(deg)C) were isolated from mud samples collected at Abano Terme spa (Italy). The cells were gram-negative motile rods, about 1.8 (mu)m in length and 0.6 (mu)m in width, occurring singly and in pairs. Cells commonly formed spheroids at one end similar to Fervidobacterium islandicum and Fervidobacterium nodosum. The new isolate differs from F. nodosum by the 7% higher G+C content of its DNA (40.6 mol%) but is similar to Fervidobacterium pennavorans and F. islandicum in its G+C content and phenotypic properties. The phylogenetic dendrogram indicates that strain Ven5 belongs to the order Thermotogales and shows the highest 16S ribosomal DNA sequence similarity to F. pennavorans, F. islandicum, and F. nodosum, with similarities of 99.0, 98.6, and 96.0%, respectively. During growth on starch the strain produced a thermostable pullulanase of type I which preferentially hydrolyzed (alpha)-1,6 glucosidic linkages. The enzyme was purified 65-fold by anion-exchange, gel permeation, and hydrophobic chromatography. The native pullulanase has a molecular mass of 240,000 Da and is composed of three subunits, each with a molecular mass of 77,600 Da as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Optimal conditions for the activity and stability of the purified pullulanase were pH 6.0 and 85(deg)C. At pH 6.0, the half-life of the enzyme was over 2 h at 80(deg)C and 5 min at 90(deg)C. This is the first report on the presence of pullulanase type I in an anaerobic bacterium.

Journal Article↗
PubMed1997

[Measurement of skin temperature as a method of detecting febrile diseases in swine].

The objective of the study was to determine whether precise estimation of rectal temperature of pigs is possible by taking their skin temperature in consideration of different factors as body weight, ambient temperature and relative air humidity. Therefore skin temperature of 272 pigs (7-222 kg BW) was measured by direct (thermo couple element) and indirect (infrared thermometer) methods at distinct localisations. In order to investigate different stages of pyretogenesis Escherichia coli endotoxin was administered to 30 of the pigs intravenously. A significant influence on skin temperature could be ascertained for the ambient temperature and the body weight, but not for the relative air humidity. From these data equations were established to estimate rectal temperature (RT) by measurement the skin temperature (ST) at the base of the ear: 1. Weaners and fattening pigs: RT = ST + 21.867 - 0.089x1 - 0.432x2 + 0.009x3, (r = 0.703) 2. Sows: RT = ST + 31.511 - 0.074x1 - 0.657x2 - 0.011x3, (r = 0.641) (x1 = ambient temperature, x2 = skin temperature, x3 = body weight) In spite of consideration of ambient temperature and body weight estimation of the rectal temperature was not suitable for clear detection of febrile pigs. Only in 35.45% of the younger pigs and in 29.30% of the sows a definite diagnose (fever yes/no) could be made. This method can only be used as a screening in the herd, if estimation of extreme values allowed the recognition of febrile illness. A follow-up control of the rectal temperature is always necessary in groups of animals, where estimations give no clear results.

Aging↗
PubMed1996

Echocardiographic quantification of regional left ventricular wall motion with color kinesis.

BACKGROUND: Color kinesis is a new technology for the echocardiographic assessment of left ventricular wall motion based on acoustic quantification. This technique automatically detects endocardial motion in real time by using integrated backscatter data to identify pixel transitions from blood to tissue during systole on a frame-by-frame basis. In this study, we evaluated the feasibility and accuracy of quantitative segmental analysis of color kinesis images to provide objective evaluation of regional systolic endocardial motion. METHODS AND RESULTS: Two-dimensional echocardiograms were obtained in the short-axis and apical four-chamber views in 20 normal subjects and 40 patients with regional wall motion abnormalities. End-systolic color overlays superimposed on the gray scale images were obtained with color kinesis to color encode left ventricular endocardial motion throughout systole on a frame-by-frame basis. These color-encoded images were divided into segments by use of custom software. In each segment, pixels of different colors were counted and displayed as stacked histograms reflecting the magnitude and timing of regional endocardial excursion. In normal subjects, histograms were found to be highly consistent and reproducible. The patterns of contraction obtained in normal subjects were used as a reference for the objective automated interpretation of regional wall motion abnormalities, defined as deviations from this pattern. The variability in the echocardiographic interpretation of wall motion between two experienced readers was similar to the diagnostic variability between the consensus of the two readers and the automated interpretation. CONCLUSIONS: Color kinesis is a promising new tool that may be used clinically to improve the qualitative and quantitative evaluation of spatial and temporal aspects of global and regional wall motion. In this initial study, segmental analysis of color kinesis images provided accurate, automated, and quantitative diagnosis of regional wall motion abnormalities.

Adult↗
PubMed1996

Summary of findings from the United States Collaborative Study of children treated for phenylketonuria.

The Collaborative Study of children treated for phenylketonuria (PKUCS) was conducted to investigate prospectively the effects of dietary restriction of phenylalanine on the growth and development of these children. Patients with classic phenylketonuria were identified by newborn screening and began treatment shortly thereafter. All were given the restricted diet until age 6 years, when half were randomly assigned to continue and half to discontinue dietary therapy. By age 10 years, 35% had deviated from randomization. The effects of diagnostic, treatment, and psychosocial factors on cognitive test scores were evaluated through 12 years of age. After controlling for parent IQ, significant correlations were noted between various measures of control of blood phenylalanine and their scores on intelligence, reading, spelling and behavior tests, but not for arithmetic or language scores. Bender Gestalt test scores were related to phenylalanine level at the time of testing, but not to early treatment history. These findings strongly support the importance of early initiation of dietary treatment and continuation of therapy throughout childhood.

Child↗
PubMed1996

The International Collaborative Study on maternal phenylketonuria: organization, study design and description of the sample.

The International Maternal Phenylketonuria (PKU) Collaborative Study commenced in 1984 to evaluate the efficacy of the low-phenylalanine diet in reducing the morbidity associated with maternal PKU syndrome. Four hundred and sixty eight (468) pregnancies resulted in 331 live births, 3 stillbirths, 61 spontaneous abortions, 2 ectopic pregnancies and 71 elective terminations. Since its inception, the study has steadily progressed toward its goal of diet initiation preconception or early in pregnancy. By 1994, 51% of the sample began the diet preconceptionally, with an additional 41% doing so by 8 weeks gestation. The number of adolescent pregnancies has decreased from 31% to 9%, college attendance has increased from 5% to 16%, number of women in the lowest socioeconomic classes has decreased from 95% to 59% and average IQ has increased from 78 to 88. The organization of the network of 130 referral centers and clinics within the U.S.A., Canada and Germany and the objectives of the scientific research investigation have served to provide a derived benefit of outreach, education, reproductive counseling and early diet intervention in a large cohort of PKU women.

Adolescent↗
PubMed1996

Outcome implications of the International Maternal Phenylketonuria Collaborative Study (MPKUCS): 1994.

It is well established that women with phenylketonuria who remain untreated during pregnancy face serious problems in offspring outcome. Surveys have documented that maternal phenylalanine (Phe) blood concentrations above 1200 mumol/l are associated with microcephaly, congenital heart disease and intrauterine growth retardation among their offspring. To investigate the efficacy of the Phe restricted diet, the National Institute of Child Health and Human Development in Bethesda Maryland developed an international study to evaluate fetal outcome in pregnancies treated with the Phe restricted diet. The study involves over 100 metabolic clinics in the United States, Canada and Germany, and is now in its 10th year. The results included in this report are still preliminary in nature and the actual risk for such pregnancies remains to be determined.

Diet, Protein-Restricted↗
PubMed1996

The North American Maternal Phenylketonuria Collaborative Study, developmental assessment of the offspring: preliminary report.

Preliminary results of 2-year Bayley and 4-year McCarthy test scores are presented. To date numbers are too small to statistically correlate:- offspring from pregnancies in which diet was started prior to conception, offspring from pregnancies with phenylalanine (Phe) levels of 120-360 mumol/l versus 360-600 mumol/l, influence of home environment, influence of maternal nutrition, language development, behaviour/hyperactivity, Revised Wechsler Intelligence Score, school performance and learning disabilities. Two-year Bayley scores (mental and motor) revealed a median developmental quotient of 113 in 58 offspring from control pregnancies, 104 in 19 offspring from untreated "non-phenylketonuria (PKU) mild hyperphenylalaninaemia" (natural Phe levels < 600 mumol/l) pregnancies, 104 in 32 offspring from pregnancies whose Phe levels decreased on treatment to < 600 mumol/l by 10 weeks gestation and remained in that range for the remainder of the pregnancy, 98 in offspring from 32 pregnancies where permanent control was not achieved until 10-20 weeks and 72 in offspring from 51 pregnancies where control was not attained until after 20 weeks gestation. IQ scores determined by the McCarthy test at age 4-5 years revealed a mean of 112 in 43 offspring of control mothers, 99 in 12 offspring of "non PKU mild hyperphenylalaninaemia" women, 93 in 14 offspring whose mother's Phe levels were continuously under 600 mumol/l by 10 weeks gestation, 88 in 24 offspring from pregnancies in metabolic control by 10-20 weeks and 73 in 28 offspring of pregnancies not in metabolic control until after 20 weeks gestation. These preliminary results suggest that early and adequate dietary treatment during pregnancy in maternal PKU may provide some protection to the fetus for later intellectual development but much more data is required before definitive statements about cognition can be made.

Child Development↗
PubMed1996

Maternal non-phenylketonuric mild hyperphenylalaninemia.

Unlike maternal phenylketonuria (PKU) which produces severe birth defects when untreated during pregnancy, maternal non-PKU mild hyperphenylalaninemia (MHP) has a less severe impact but whether it is benign or may have long-term consequences for offspring has been unclear. From an international survey of maternal MHP we obtained information about 86 mothers (blood phenylalanine (Phe) 150-720 mumol/l), their 219 untreated pregnancies and 173 offspring. Spontaneous fetal loss and congenital anomalies were no more frequent than normally expected. Median Z-scores for birth length and birth head circumference and offspring IQ (100), however, were significantly lower for maternal Phe > 400 mumol/l than for maternal Phe < 400 mumol/l, in which the median offspring IQ was 108. Data on maternal MHP from the prospective Maternal PKU Collaborative Study (MPKUCS) are as yet incomplete but seem to be conforming to the general pattern of the international survey. We conclude that maternal blood Phe levels above 400 mumol/l in maternal MHP are associated with lower birth measurements and slightly lower offspring IQ. It would seem that dietary intervention to lower the maternal Phe levels to below 400 mumol/l might be indicated in maternal MHP pregnancies with the higher blood Phe levels.

Adult↗
PubMed1996

Care of the adult with phenylketonuria.

Forty-three adults with classical phenylketonuria were identified by neonatal screening and treated with a phenylalanine (Phe) restricted diet. Nineteen have remained on dietary treatment with varying levels of blood Phe control and 24 have discontinued the diet at an average age of 7.8 years. Follow up at an average age of 22 years revealed that the cohort remaining on dietary treatment have achieved substantially better social and academic achievement than the 24 who discontinued dietary treatment. Another group of 19 adults who were not diagnosed until an average age of 2.5 years have also been evaluated after an average of 22 years on a Phe restricted diet. This report is based upon Wechsler Adult Intelligence Revised Test scores, attendance at college, employment and marital status.

Adolescent↗
PubMed1996

A computer based, temperature controlled bipolar electrocoagulation system.

OBJECTIVE: To reduce complications during electrocoagulation particularly injury of other organs, a computer based, temperature controlled bipolar coagulation system has been developed. Under this system temperature in the tissue is kept between 60 degrees C and 95 degrees C during coagulation. A real time graphic display provides the surgeon with an actual temperature at the tip of the forceps during coagulation. STUDY DESIGN: Rabbit uterine horns were coagulated at 90 degrees C and were examined histologically and histochemically at 6 weeks after coagulation. RESULTS: Electrocoagulation at 90 degrees C induced a total loss of LDH activity in the tissue. Lumen of the uterus was completely occluded when examined 6 weeks later. CONCLUSION: This system with low temperature is sufficient for homogenous coagulation of the tissue.

Animals↗
PubMed1996

Patterns and prediction of orthodontic treatment course.

Most attempts at the identification and prediction of treatment-related changes and outcome in orthodontics thus far have relied upon single biometric parameters instead of employing a systemic and ecological approach. The concept of facial harmony and the availability of sophisticated multivariate statistics offer new chances for a deeper understanding of the mechanisms of change. A longitudinal study has been conducted on approximately 500 youths aged 9-11 years, on average. Numerous parameters of cephalometric analysis, study casts, growth, treatment regimen and patient co-operation were assessed at the onset of treatment (T0) and after 1 year (T1) to determine treatment-related changes under therapy with removable appliances. Exploratory cluster analyses were based on five fundamental cephalometric parameters (SNA, SNB, ML-NSL, NL-NSL, NS-Ba) that establish an operational approach to harmonious facial relations (Segner and Hasund, 1991). As a first step, analyses were restricted to 281 Class II division 1 patients selected for good co-operation by an expert rating by the first author on a three-point rating scale. They all were treated with bionators either with anterior or posterior traction. Both subgroups were studied separately. Based on cluster analytic procedures, different patterns of change were identified for both types of appliance. A slight tendency toward harmonization of the initial skeletal relations was observed throughout all subgroups, with reactions being most obvious in the maxilla. The clusters produced for either appliance group were then screened for additional predictors of group membership by means of discriminant analysis. The findings are discussed in terms of the suitability of the methodological approach chosen.

Activator Appliances↗