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C Walter

Publications and source records attributed to C Walter.

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

Comparative studies on Na-dependent Pi transport in ovine, caprine and porcine renal cortex.

In contrast to monogastric species, renal excretion of inorganic phosphate (Pi) in ruminants is low and this could be attributed to an almost complete tubular Pi reabsorption. However, the functional and regulatory basis for this phenomenon has not yet been clarified. Therefore, it was the aim of the present study to characterize the kinetic parameters of the tubular Pi reabsorption system as affected by P or Ca depletion using preparations of renal cortex brush border membrane vesicles (BBMV) from goats and sheep and to compare the data with respective parameters of porcine preparations. Na-dependent Pi uptake into renal cortex BBMV as a function of Pi concentration showed typical Michaelis-Menten kinetic and respective Scatchard plot analysis of the specific Pi uptake revealed linearity indicating the predominant presence of a single type of Pi transporters in the preparations. Under control conditions Vmax values of Na-dependent Pi uptake into BBMV were highest in goats and sheep and lowest in pigs (1.98, 1.39 and 0.95 nmol x mg(-1) protein x 10s(-1), respectively). Km values were not different between goats and sheep under all feeding conditions and ranged from between 0.34 mmol x l(-1) and 0.55 mmol x l(-1) which was three- to five-times higher than that found in pigs (0.11 mmol x l(-1)). Oligonucleotides derived from rat kidney cortex type IIa Na/Pi cDNA were used for reverse transcriptase-polymerase chain reaction (RT-PCR) in goat, sheep and pig kidney cortex. The products isolated were 768 bp for sheep and pigs and 765 bp for goats, with the respective amino acids sequences, representing a segment of approximately 40% in length of the entire transporter, exhibiting an at least 92% sequence homology between different species. From the results, involvement of type IIa Na/Pi cotransport in tubular Pi reabsorption in small ruminants can be postulated. However, it should not be considered that a potential role of other Pi transport systems be completely be excluded. Interestingly, neither P nor Ca depletion caused significant effects on Na-dependent Pi transport capacities and affinities in goats and sheep. From this, parathyroid-hormone independent regulatory pathways of tubular Pi reabsorption can be assumed.

Animals↗
PubMed2000

Titanium clamps for refixation of bone fragments in the repair of depressed skull fractures: technical note.

The rigid fixation of bone fragments in the repair of depressed skull fractures can be a problem, especially if not all fragments are replaceable. Usually, in these cases mini- or microplates are used. The Craniofix titanium clamp (Aesculap, Germany) was developed for the fixation of bone flaps after osteoplastic craniotomy. It consists of a screw holding together two 10-mm diameter metallic disks with concaved teeth pressing bone flap and cranium between the two disks. We used this system for the operative treatment of two patients with depressed skull fracture. A rigid fixation of the bone fragments was achieved in both cases. The postoperative three-dimensional CT scan showed a good fragment alignment. From the report of two cases we show that this system is a useful tool in the fixation of bone fragments in the repair of depressed skull fractures.

Adult↗
PubMed2000

[Precision of MRI-guided needle placement--experimental results].

PURPOSE: To estimate the accuracy of the determination of tip position of MR compatible biopsy needles based on signal voids and artifacts in MR guided biopsies. METHOD: In a nylon grid phantom an MR compatible 18G needle (E-Z-EM) was measured in a 1.0 T imager using TSE- and FFE-sequences of 20 s and 40 s duration in 34 different orientations of needle versus B0, frequency and slice selection gradient. 4 radiologists with no experience in the evaluation of signal void artifacts estimated the needle tip positions from needle tip artifacts. The readers determined the needle tip before and after a 15 minute training session based on high resolution images with explanation of size and shape of specific artifacts of biopsy needles in 12 different orthogonal or parallel orientations to B0 and frequency encoding gradient that are possible if the needle lies parallel to the slice, i.e. orthogonal to the slice selection gradient. The values obtained before and after the training session were compared to the real position of the needle tip. RESULTS: Mean distance of actual needle tip and tip position as determined from images was 1.8 +/- 2.3 mm in TSE-versus 2.5 +/- 1.2 mm in FFE-images, with the needle length overestimated. After a 15 minute training session the positioning error decreased significantly to 0.2 +/- 1.8 mm for TSE-sequences and to 1.0 +/- 1.8 mm for FFE-sequences. A higher accuracy of tip localization was obtained with TSE sequences. CONCLUSION: In MR guided biopsies using FFE- and TSE-sequences the needle position can be more accurately determined if the reader is familiar with the 12 orthogonal or parallel positions of the needle with respect to B0 and frequency encoding gradient and the corresponding artifacts.

Artifacts↗
PubMed1999

The KID Study V: the natural history of type 2 diabetes in younger patients still practising a profession. Heterogeneity of basal and reactive C-peptide levels in relation to BMI, duration of disease, age and HbA1.

In a detailed evaluation of the data accumulated for 493 type 2 diabetics who participated in the KID Study, pre- and postprandial C-peptide was correlated with blood glucose level, HbA1, body mass index (BMI), duration of disease and age. As described earlier the KID-Study examined a younger cohort of type 2 diabetics predominately practising a profession. Our investigations demonstrate a significant increase of pre- as well as postprandial C-peptide levels with increasing obesity. However, delta C-peptide, as an indicator at the reaction capacity of pancreatic secretion, decreases significantly and continuously. Pre- as well as postprandial C-peptide levels decrease significantly with up to 15-20 years duration of disease. The preprandial pancreatic secretion is usually even at a high normal level at such a late stage whereas the secretory reserve of normal or mildly overweight as well as of obese type 2 diabetics is more impaired. In contrast to patients with a BMI < 30, obese patients with a BMI > 30 will also develop impairment of basal insulin secretion over decades. The patient's age did not influence the pre- or postprandial insulin secretion. The quality of metabolic control as measured by the HbA1 has nearly exclusive impact on the secretory reserve capacity. Correlation with increasing HbA1 concentrations, the postprandial but not the preprandial C-peptide levels decreased significantly and continuously. Predictive factors for a deterioration in pancreatic function are in order of importance: the extent of obesity, the quality of metabolic control and only last the duration of diabetes. Fortunately, consistent diabetic care can have an impact on the first two.

Age of Onset↗
PubMed1999

The KID Study VI: diabetic complications and associated diseases in younger type 2 diabetics still performing a profession. Prevalence and correlation with duration of diabetic state, BMI and C-peptide.

A sub-study evaluated 698 younger (54.5 +/- 6.9 years) type 2 diabetics of the KID Study participants to establish the prevalence of diabetic complications and associated diseases and their correlation with body mass index (BMI), duration of disease and to C-peptide levels. Only 19.8% of the type 2 diabetics had a normal weight. In all weight subgroups, the average age of diabetes manifestation were around age 45. In 46.6% of all type 2 diabetics we could already demonstrate microangiopathic complications. Strikingly, 15.9% of the patients already had proliferative retinopathies and 12.6% had albuminuria of more than 1000 mg/dl. 74.7% of our type 2 diabetics presented with the well-known risk cluster of the metabolic syndrome: In every other patient, we found hypertension and/or hyperlipoproteinaemia. Accordingly, the prevalence of the macroangiopathic diabetic complications, coronary artery disease and peripheral vascular disease was 17.8%, which is high for a relatively young population with a mean age of 53.9 years and goes conform with recent literature (Lowel et al., 1999). An increase in BMI correlated significantly with deterioration of HbA1, a decrease in HDL cholesterol, an increase in triglycerides and with a higher prevalence of hypertension. The frequency of nephropathy increase significantly up to a BMI of 30-35 kg/m2. Retinopathies and polyneuropathies were associated with BMI but increased significantly with the duration of the diabetic state. In contrast to microangiopathic diabetic complications, there was already a high prevalence of nephropathy after a comparatively short duration of disease. The prevalence of hyperlipoproteinaemia and hypertension did not depend from the duration of diabetes. These concomitant diseases already were frequent early in the disease and did not increase with the duration of disease. However, there was a strong correlation between increasing hyperlipoproteinaemia and hypertension and higher C-peptide levels. We found no coincidence between C-peptide levels and microangiopathic diabetic complications.

Adult↗
PubMed1999

[MR-compatible and conventional marker wires in breast diagnosis--experimental studies on their dislocatability and artifact size in MRT].

PURPOSE: Localization of non-palpable suspicious breast lesions with tumor localization wires is commonly used before surgical excision. Dislocation of the wire is possible. The possibility of dislocation for different types of tumor localization wires was examined experimentally. METHODS: 22 different tumor localization wires were inserted into the subcutaneous fat-tissue of a pig. The wire tip was recorded under fluoroscopy. Traction was applied to the wire using a spring-balance. The artifact size of MR-compatible wires was examined in a 1.0 Tesla MR imager. RESULTS: The localization wires with an X-configuration and long hook could not be dislocated by a force up to the maximum of 12 Newton. The retractable localization wires were easily dislocated at traction forces of 1 Newton. Other wires with only one hook could withstand a traction from 2 up to 7 Newton. The wires with a Z-configuration and wires with short hooks showed a highly variable rate of resistance. The artifact size of localization systems was between 10.1 and 11.0 mm for gradient-echo sequences and between 6.7 and 7.1 mm for spin-echo sequences. CONCLUSION: Tumor localization wires with an X-configuration and long hooks were best anchored in the tissue. The advantage of repositioning retractable wires is confined by the high risk of accidental dislocation. No reliable fixation in the tissue could be achieved using wires with a Z-configuration and wires with short hooks. MR-compatible wires were comparable to non-MR-compatible wires concerning the rate of resistance. The size of the artifacts of MR-compatible systems showed no relevant differences.

Adipose Tissue↗
PubMed1999

Genes expressed in Pinus radiata male cones include homologs to anther-specific and pathogenesis response genes.

We describe the isolation and characterization of 13 cDNA clones that are differentially expressed in male cones of Pinus radiata (D. Don). The transcripts of the 13 genes are expressed at different times between meiosis and microspore mitosis, timing that corresponds to a burst in tapetal activity in the developing anthers. In situ hybridization showed that four of the genes are expressed in the tapetum, while a fifth is expressed in tetrads during a brief developmental window. Six of the seven cDNAs identified in database searches have striking similarity to genes expressed in angiosperm anthers. Seven cDNAs are homologs of defense and pathogen response genes. The cDNAs identified are predicted to encode a chalcone-synthase-like protein, a thaumatin-like protein, a serine hydrolase thought to be a putative regulator of programmed cell death, two lipid-transfer proteins, and two homologs of the anther-specific A9 genes from Brassica napus and Arabidopsis. Overall, our results support the hypothesis that many of the reproductive processes in the angiosperms and gymnosperms were inherited from a common ancestor.

Acyltransferases↗
PubMed1999

Effects of staphylococcal enterotoxins on human neutrophil functions and apoptosis.

Staphylococcal enterotoxins have marked effects on the properties of T cells and monocytes and have recently been reported to affect neutrophil function. In this study, we investigated the abilities of staphylococcal enterotoxins A and B and toxic shock syndrome toxin 1 to affect respiratory burst activity and to delay apoptosis in human neutrophils. When cultures containing approximately 97% neutrophils were tested, the toxins all delayed neutrophil apoptosis in a dose-dependent manner and induced the expression of FcgammaRI on the neutrophil cell surface. These effects on apoptosis and expression of FcgammaRI were largely abrogated by the addition of a neutralizing anti-gamma interferon antibody. Similarly, the effects of these toxins on phorbol ester-induced chemiluminescence were decreased after neutralization of gamma interferon. These effects on neutrophil function were mimicked by the addition of conditioned medium from peripheral blood mononuclear cells incubated with the toxins, and again, neutralizing anti-gamma interferon antibodies largely negated the effects. However, when highly purified neutrophils prepared by immunodepletion of T cells and major histocompatibility complex class II-expressing cells were analyzed, the toxins were without effect on apoptosis and FcgammaRI expression, but granulocyte-macrophage colony-stimulating factor and gamma interferon could still delay apoptosis. These data indicate that these toxins have no direct effect on neutrophil apoptosis but can act indirectly via the production of T-cell-derived and monocyte-derived cytokines. It is noteworthy that such effects are detected in neutrophil suspensions containing only 3% contamination with T cells and other mononuclear cells.

Apoptosis↗
PubMed1999

Endothelial cell dysfunction and arterial wall hypertrophy are associated with disturbed carbohydrate metabolism in patients at risk for cardiovascular disease.

To investigate the effects of fasting and postprandial glucose on endothelial cell function and intima-media thickness, we studied 60 men with cardiovascular risk factors. Postischemic, endothelium-dependent vasodilatation was measured after 3 minutes of ischemia at the radial artery with high-resolution echo tracking. Common carotid artery intima-media thickness was measured by B-mode ultrasound. Glucose tolerance was determined by a 75-g oral glucose load. Fasting glucose levels were inversely correlated with postischemic, endothelium-dependent vasodilatation (r=-0.24, P<0.05) and directly correlated with intima-media thickness (r=0.26, P<0.05). However, postischemic, endothelium-dependent vasodilatation and intima-media thickness were not correlated. All subjects with normal postischemic, endothelium-dependent vasodilatation also had a normal intima-media thickness, whereas some subjects with impaired postischemic, endothelium-dependent vasodilatation also had a normal intima-media thickness. Multiple regression analysis revealed a profound influence of age on intima-media thickness to the exclusion of all other variables. The same age-adjusted analysis for postischemic, endothelium-dependent vasodilatation accepted fasting glucose, followed by 2-hour postprandial glucose, as variables, but no others. Subjects with fasting glucose values >100 mg/dL showed reduced postischemic, endothelium-dependent vasodilatation (59 versus 120 microm, P<0.05) and a higher intima-media thickness (right: 0.76 versus 0.62 mm, P<0.05; left: 0.78 versus 0.63 mm, P<0. 05) compared with those with fasting glucose values <100 mg/dL. Subjects with 2-hour postprandial glucose values >125 mg/dL had no reduced postischemic, endothelium-dependent vasodilatation compared with subjects with a 2-hour postprandial glucose <125 mg/dL; however, their intima-media thickness (right: 0.66 versus 0.62 mm; left: 0. 68 versus 0.62 mm; P<0.05 for both) was greater. Thus, high fasting rather than postprandial glucose values are associated with both postischemic, endothelium-dependent vasodilatation and increased intima-media thickness. Postischemic endothelium-dependent vasodilatation may precede increased intima-media thickness.

Adult↗
PubMed1998

PRFLL--a Pinus radiata homologue of FLORICAULA and LEAFY is expressed in buds containing vegetative shoot and undifferentiated male cone primordia.

In angiosperms, the formation of the flower meristem is controlled by partially redundant flower meristem identity genes of which FLORICAULA (FLO)/LEAFY (LFY) plays a central role. It is not known whether formation of reproductive organs of pre-angiosperm species is similarly regulated. Recently, a FLO/LFY-like cDNA, NEEDLY (NLY), has been cloned in a conifer species Pinus radiata (D. Don). Here we report cloning of a different Pinus radiata FLO/LFY-like cDNA, PRFLL. PRFLL had two large regions of high similarity to angiosperm FLO/LFY orthologues: amino acids 61-126 and 247-406 (50% and 81% identity, and 75% and 88% similarity, respectively, to LFY) and shorter regions of local similarity. Overall identity was 53% to LFY and 61% to NLY. Phylogenetic analysis of deduced protein sequences including partial LFY-like sequences from Pseudotsuga menziesii indicated that conifer proteins constituted a separate clade that could be divided into two groups represented by NLY and PRFLL. In contrast to angiosperms, both conifers had two paralogous proteins resembling LFY. Northern hybridisation analysis revealed expression of PRFLL in vegetative buds of juvenile, adolescent and mature trees. The transcript was not detected in vascular cambium, roots or secondary needles. To follow PRFLL expression during the early stages of cone development we analysed a temporal series of buds containing cone primordia, and developing cones, using Northern hybridisation and confocal microscopy in parallel. PRFLL mRNA was detected in buds from dominant and subordinate branches, in which cone and shoot primordia develop, and in developing male cones but not in developing female cones. Expression was particularly high in buds containing axillary primordia prior to their differentiation as male cone primordia. This is consistent with PRFLL being involved in determination of the male cone primordium identity.

Amino Acid Sequence↗
PubMed1998

Influence of the hepatobiliary contrast agent mangafodipir trisodium (MN-DPDP) on the imaging properties of abdominal organs.

To assess the influence of Mangafodipir Trisodium on the imaging properties of abdominal organs when using T1-weighted gradient-echo (GE) and T2-weighted turbo spin-echo (TSE) sequences, thirty patients with focal lesions in the liver were examined at a field strength of 1.5 T before and after intravenous administration of Mangafodipir Trisodium (dose: 5 micromol/kg of body weight). Administration of Mangafodipir Trisodium led to a significant increase in the signal intensity of the liver tissue (p < 0.001), the spleen (p < 0.01), the pancreas (p < 0.001), and the kidneys (p < 0.001) in the T1-weighted GE sequence, while there was no relevant enhancement in fatty tissue and the musculature. In the T2-weighted turbo spin-echo sequence, there was no relevant change in the signal following administration of a contrast agent. The contrast-to-noise ratio (C/N) between the lesions and the liver tissue increased significantly in the post-contrast T1-weighted GE sequence (p < 0.001), while there was no change in the contrast-to-noise ratio in the post-contrast T2-weighted turbo spin-echo sequence. The contrast-to-noise ratio of the plain T2-weighted TSE sequence was significantly higher than that in the post-contrast T1-weighted GE sequence (p < 0.001). Although Mangafodipir Trisodium was primarily developed as a hepatobiliary contrast agent for demonstration and differentiation of liver lesions, it also affects the signal levels in the pancreas, spleen, and kidneys in the T1-weighted image. Awareness of this effect on the extrahepatic tissue makes it easier to interpret pathological findings in magnetic resonance imaging (MRI) of the abdomen.

Abdomen↗
PubMed1998

Detection of focal hepatic lesions: effects of superparamagnetic iron oxide (AMI-25) on magnetic resonance imaging of the liver using T2-weighted fast spin-echo sequences and gradient-and-spin-echo sequences at 1.0 tesla.

RATIONALE AND OBJECTIVES: The authors evaluate the value of two fast spin-echo sequences (FSE) with different T2-weighting (repetition time [TR]/echo time [TE] = 2000/90 mseconds and TR/TE = 2000/40 mseconds) and combined gradient-and-spin-echo sequences (TR/TE = 2000/90 mseconds) for contrast-enhanced liver imaging with superparamagnetic iron oxide (AMI-25). METHODS: Forty-seven patients with focal liver lesions underwent magnetic resonance imaging at 1.0 tesla. AMI-25 was administered intravenously at a dose of 15 micromol iron/kg. RESULTS: Administration of AMI-25 resulted in a significant increase of lesion/liver contrast-to-noise ratio (C/N) for all T2-weighted sequences (P < 0.001). On the precontrast images, the FSE sequence with a TE of 90 mseconds had the highest C/N (16.0 +/- 4.5) whereas the best postcontrast C/N (27.9 +/- 7.6) was obtained with the mild T2-weighted FSE sequence with a TE of 40 mseconds. CONCLUSIONS: Fast spin-echo sequences are valuable sequences for imaging of the liver at 1.0 tesla. For AMI-25-enhanced magnetic resonance imaging, a mild T2-weighted FSE sequence is recommended.

Adult↗
PubMed1998

Use of the hand test in the assessment of combat-related stress.

This study investigated the effectiveness of the Hand Test in discriminating the differential symptomatology of posttraumatic stress (PTS) in Vietnam combat veterans (VCVs). Participants were 108 VCV outpatients, 85 of whom met the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]; American Psychiatric Association, 1994) criteria for posttraumatic stress disorder (PTSD), and 23 patients that were found to meet some, but not the minimum criteria, required for a diagnosis of PTSD by the DSM-IV. The latter group of patients was classified into a subclinical PTSD, posttraumatic stress symptoms (PTSS) group. Results showed higher levels of overall psychopathology, a vulnerable capacity for coping, and a tendency for feelings of inadequacy and inferiority in the PTSD group. The PTSD group also exhibited more limited interaction with the world around them than the PTSS group, which may be indicative of withdrawal, apathy, or a lack of concern with environmental activities and goals. These findings are discussed in relation to the assessment, understanding, and treatment of PTS symptomatology and PTSD.

Adult↗