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Biomedical subjects

K Voss

Publications and source records attributed to K Voss.

At least 19 recordsLinked to original sources
PubMed2006

Use of the ComPact UniLock System for ventral stabilization procedures of the cervical spine: a retrospective study.

This study evaluates clinical application of the ComPact UniLock system for ventral stabilization of the cervical spine. Patient material included 13 consecutive cases, 12 dogs and one cat, with cervical spinal instabilities secondary to disc-associated wobbler syndrome (six dogs), traumatic, iatrogenic, and disc-associated cervical spinal instability of small dogs (four cases), cervical spinal fractures (one dog and one cat), and congenital atlantoaxial instability (one dog). The 2.0 system was used in smaller patients and the 2.4 system was applied in large dogs. Implant failure was observed on follow-up radiographs in one dog with a healed C2 fracture and screw pullout occurred in one dog with caudal cervical spondylomyelopathy, necessitating revision surgery. Implants remained stable throughout the follow-up period in the other cases. 'Good' or 'excellent' clinical outcome was achieved in 12 patients, including the dog with revision surgery. One dog had to be euthanatized due to postoperative deterioration of neurological status and development of pneumonia. The ComPact UniLock system was found to be a suitable implant for treating cervical instabilities of different origin in both small and large patients with lesions from C1/C2 to C6/C7. Some problems were encountered in the dogs with disc-associated Wobbler syndrome, such as lack or slow rate of vertebral fusion and partial collapse of the distracted intervertebral space on follow-up radiographs. A lack of adequate fusion was most likely related to grafting techniques used.

Animals↗
PubMed2005

The ComPact UniLock 2.0/2.4 system and its clinical application in small animal orthopedics.

This study describes the titanium ComPact UniLock 2.0/2.4 locking plate system (Stratec Medical, Oberdorf, Switzerland) and reports its application in nine selected clinical cases. The system was found useful for a variety of indications. Three categories of clinical applications are illustrated. They include (a) long bone fractures, (b) cervical spinal fractures and instabilities and (c) joint instabilities and luxations. A brief introduction to the system has already been published

Animals↗
PubMed2004

Autonomous activity of CaMKII is only transiently increased following the induction of long-term potentiation in the rat hippocampus.

A major role has been postulated for a maintained increase in the autonomous activity of CaMKII in the expression of long-term potentiation (LTP). However, attempts to inhibit the expression of LTP with CaMKII inhibitors have yielded inconsistent results. Here we compare the changes in CaMKII autonomous activity and phosphorylation at Thr286 of alphaCaMKII in rat hippocampal slices using chemical or tetanic stimulation to produce either LTP or short-term potentiation (STP). Tetanus-induced LTP in area CA1 requires CaMKII activation and Thr286 phosphorylation of alphaCaMKII, but we did not observe an increase in autonomous activity. Next we induced LTP by 10 min exposure to 25 mM tetraethyl-ammonium (TEA) or 5 min exposure to 41 mM potassium (K) after pretreatment with calyculin A. Exposure to K alone produced STP. These protocols allowed us to monitor temporal changes in autonomous activity during and after exposure to the potentiating chemical stimulus. In chemically induced LTP, autonomous activity was maximally increased within 30 s whereas this increase was significantly delayed in STP. However, in both LTP and STP the two-fold increase in autonomous activity measured immediately after stimulation was short-lived, returning to baseline within 2-5 min after re-exposure to normal ACSF. In LTP, but not in STP, the phosphorylation of alphaCaMKII at Thr286 persisted for at least 60 min after stimulation. These results confirm that LTP is associated with a maintained increase in autophosphorylation at Thr286 but indicate that a persistent increase in the autonomous activity of CaMKII is not required for the expression of LTP.

Animals↗
PubMed2001

Lameness in feedlot cattle.

This article examines the various causes of lameness in feedlot cattle, with an emphasis on clinical signs, treatment, and prevention. Specific conditions are discussed, including interdigital necrobacillosis, laminitis, feedlot injuries, and feedlot lameness associated with Mycoplasma bovis. Immune management of the foot is also reviewed.

Animals↗
PubMed2001

Subfield-specific immediate early gene expression associated with hippocampal long-term potentiation in vivo.

It is not known whether NMDA receptor-dependent long-term potentiation (LTP) is mediated by similar molecular mechanisms in different hippocampal areas. To address this question we have investigated changes in immediate early gene and protein expression in two hippocampal subfields following the induction of LTP in vivo and in vitro. In granule cells of the dentate gyrus, LTP induced in vivo by tetanic stimulation of the perforant path was followed by strong induction of the immediate early genes (IEGs) Zif268, Arc and Homer. The increase in Zif268 mRNA was accompanied by an increase in protein expression. In contrast, we were unable to detect modulation of the IEGs Zif268, Arc, Homer and HB-GAM following induction of LTP by high-frequency stimulation of the commissural projection to CA1 pyramidal cells in vivo. In this pathway, we also failed to detect modulation of Zif268 protein levels. Zif268, Arc and Homer can be modulated in CA1 pyramidal cells approximately twofold after electroshock-induced maximal seizure, which demonstrates potential responsiveness to electrical stimuli. When LTP was induced in vitro neither CA1 pyramidal cells nor granule cells showed an increase in Zif268, Arc or Homer mRNA. However, in the slice preparation, granule cells have a different transcriptional state as basal IEG levels are elevated. These results establish the existence of subfield-specific transcriptional responses to LTP-inducing stimulation in the hippocampus of the intact animal, and demonstrate that in area CA1-enhanced transcription of Zif268, Arc and Homer is not required for the induction of late LTP.

Animals↗
PubMed2001

Seizure-induced gene expression in area CA1 of the mouse hippocampus.

Synaptic plasticity in the hippocampus requires activity-dependent gene expression. We have therefore profiled gene expression in area CA1 following the induction of an electroshock-evoked maximal seizure. Using cDNA microarrays, the differential expression of approximately 9000 cDNAs was examined. In situ hybridization on 14 transcripts that showed strongest modulation in the microarray screen (1.8-2-fold) confirmed the differential expression of a single gene that encodes for the nuclear hormone receptor NGFI-B (Nur77, N10). Although this gene is only modestly up-regulated (approximately 2-fold) in area CA1, in situ hybridization revealed that maximal seizures induce a marked (approximately 12-fold) up-regulation of NGFI-B in the dentate gyrus. These data support the notion [French et al. (2001) Eur. J. Neurosci., 13, 968-976] that CA1 pyramidal neurons are more refractory than granule cells of the dentate gyrus with respect to activity-dependent gene transcription. Furthermore, our results argue against a large cohort of activity-dependent genes in area CA1.

Animals↗
PubMed2000

Determination of L- and D-amino acids in foodstuffs by coupling of high-performance liquid chromatography with enzyme reactors.

A technique is described for the enantiomeric determination of L- and D-amino acids. It works on the principle that the separation efficiency of high-performance liquid chromatography is coupled with the specificity of enzymes and the sensitivity of electrochemical detection. After separation on a lithium cation-exchange column the amino acids are converted into keto acids and hydrogen peroxide under catalyzation of L- or D-amino acid oxidase. Hydrogen peroxide is detected amperometrically. The method has been tested by the analysis of beer, port, sherry, wine and fruit juice. A main emphasis was put onto the determination of D-alanine which can serve as an indicator for bacterial contamination. It is shown that a coupling of HPLC with enzyme reactors is a suitable technique for the rapid detection of this marker.

Amino Acid Oxidoreductases↗
PubMed1996

Enhanced tyrosine phosphorylation of the 2B subunit of the N-methyl-D-aspartate receptor in long-term potentiation.

Both serine/threonine and tyrosine phosphorylation of receptor proteins have been implicated in the process of long-term potentiation (LTP), but there has been no direct demonstration of a change in receptor phosphorylation after LTP induction. We show that, after induction of LTP in the dentate gyrus of anesthetized adult rats, there is an increase in the tyrosine phosphorylation of the 2B subunit of the N-methyl-D-aspartate (NMDA) receptor (NR2B), as well as several other unidentified proteins. Tyrosine phosphorylation of NR2B was measured in two ways: binding of antiphosphotyrosine antibodies (PY20) to glycoprotein(s) of 180 kDa (GP180) purified on Con A-Sepharose and binding of anti-NR2B antibodies to tyrosine-phosphorylated proteins purified on PY20-agarose. Three hours after LTP induction, anti-NR2B binding to tyrosine phosphorylated proteins, expressed as a ratio of tetanized to control dentate (Tet/Con), was 2.21 +/- 0.50 and PY20 binding to GP180 was 1.68 +/- 0.16. This increase in the number of tyrosine phosphorylated NR2B subunits occurred without a change in the total number of NR2B subunits. When the induction of LTP was blocked by pretreatment of the animal with the NMDA receptor antagonist MK801, the increase in PY20 binding to GP180 was also blocked (Tet/Con = 1.09 +/- 0.26). The increased PY20 binding to GP180 was also apparent 15 min after LTP induction (Tet/Con = 1.41 +/- 0.16) but not detectable 5 min after LTP induction (Tet/Con = 1.01 +/- 0.19). These results suggest that tyrosine phosphorylation of the NMDA receptor contributes to the maintenance of LTP.

Amino Acid Sequence↗
PubMed1996

The political economy of inequality in the "age of extremes".

Massey's presidential address correctly points to growing economic inequality as one of the pressing issues of our day, but his analysis gives short shift to the political institutions that underlie the economic trends. We supplement his analysis with a review of some of those institutions. In particular we point out how politics mediates between computerized production and inequality, between the segregation of education and inequality, and (drawing directly from American Apartheid) between housing markets and residential segregation.

Computers↗
PubMed1995

Methotrexate therapy of psoriasis: differential sensitivity of proliferating lymphoid and epithelial cells to the cytotoxic and growth-inhibitory effects of methotrexate.

Although methotrexate (MTX) is one of the most clinically effective therapies employed to treat psoriasis, the mechanism by which low-dose MTX acts to modulate the hyperplasia of psoriasis, leading to the restoration of clinically normal skin, is only partially understood. MTX has been considered a cytotoxic agent that mediates its effect primarily on proliferating or cycling epidermal cells. Recently, proliferating lymphoid cells have been identified in psoriatic lesions, raising the possibility that proliferating lymphoid cells could be another target cell that is killed by MTX. In this study, we examined the growth-inhibitory and cytotoxic effects of MTX on proliferating lymphoid cells [THP-1 (macrophage), and MOLT-4 (T cell)], epithelial cells (HeLa, and HaCat), and normal human keratinocytes (NHK) in vitro. The proliferating cells were exposed to MTX for 24 h, and placed in fresh media to mimic the transient MTX blood levels that result from once-weekly therapy. THP-1 and MOLT-4 were found to be 10-100 times more sensitive to the cytotoxic effects of MTX than were HeLa and HaCat, and more than 1000 times more sensitive than primary human keratinocytes. At MTX concentrations that would be expected to occur in vivo during once-weekly therapy, a large percentage (> 95%) of proliferating lymphoid targets would be killed, and only a small percentage (< 10%) of proliferating epidermal cells would be affected. This in vitro data suggests that in psoriasis proliferating lymphoid cells are more likely than epithelial cells to be a major cellular target of MTX in vivo.

Cell Division↗
PubMed1995

The effect of ketanserin upon postoperative blood pressure, cerebral blood flow and oxygen metabolism in patients subjected to craniotomy for cerebral tumours.

Hypertension and cerebral hyperperfusion are often seen in the immediate postoperative period after craniotomy for supratentorial tumours. This study was performed to evaluate the effect of ketanserin, given at the end of the peroperative period, upon cerebral blood flow (CBF), and cerebral metabolic rate of oxygen (CMRO2) before extubation. Mean arterial blood pressure (MABP), cerebral arterio-venous oxygen content difference (AVDO2), PaO2, and PaCO2 were repeatedly measured during the operation, and 180 minutes after extubation. Ten patients were included in this study. The results were compared to those from a recent study in which ten patients served as control. All patients were anaesthetized with thiopentone, fentanyl, nitrous oxide 67%, halothane 0.5% anesthesia. Ten patients were given ketanserin 10-20 mg (mean 18.5 mg) before extubation. There was no significant difference in CBF- and CMRO2 values between the two groups. During the period between closure of the dura and 5 minutes after extubation, an increase in MABP was observed in the control group (P < 0.05) but not in the ketanserin group. During the same period, a decrease in AVDO2 was observed in both groups (P < 0.05) and during the next 10 minutes an increase was observed. However, no difference in AVDO2 values between the two groups was found. These findings suggest that peroperative treatment with ketanserin reduces postoperative hypertension without influencing the cerebral blood flow or metabolism.

Adult↗
PubMed1990

Cognitive test profile analysis for the identification of dementia of the Alzheimer type.

Two measures of profile similarity have been derived that offer complementary information about the classification of patients with diagnoses of probable dementia of the Alzheimer type (DAT). These measures were obtained for 31 probable DAT patients and 31 age- and education-matched controls using a set of six newly constructed cognitive scales designed to provide reliable measurement in both patient and control groups. A measure assessing similarity to the average performance of the controls provided perfect separation of the patient and control groups. A measure assessing similarity to the average performance of the probable DAT patients identified up to four atypical cases of probable DAT. One of these four cases has come to autopsy and was found to have Pick disease. The cognitive profiles of this Pick patient and an autopsy-confirmed DAT patient are compared to illustrate the potential advantages of using DAT patients as the reference group for profile analysis.

Aged↗
PubMed1989

In vitro and in vivo effects of sodium selenite on 7,12-dimethylbenz[a]anthracene--DNA adduct formation in isolated rat mammary epithelial cells.

Supplementation with increasing quantities of selenium (Se), as sodium selenite, to cultures of rat mammary epithelial cells resulted in a proportional depression in 7,12-dimethylbenz[a]anthracene (DMBA) binding to DNA. A depression in the two major anti bay-region dihydrodiol epoxide-deoxyribonucleoside adducts largely accounted for the reduced binding. DMBA-DNA binding in freshly isolated mammary cells from rats fed a diet containing 2.0 p.p.m. Se and incubated in culture with DMBA for 24 h was decreased 32% compared to binding in cells obtained from rats fed 0.1 p.p.m. Se. DMBA-DNA binding in mammary cells obtained from rats fed supplemental Se for 2 weeks or more was depressed compared to that occurring in cells from unsupplemented rats. The reduced ability of cells obtained from rats previously fed a 2.0 p.p.m. Se diet to activate DMBA to intermediates capable of binding to DNA became increasingly apparent with the duration of exposure to the carcinogen. Consistent with the in vitro supplementation study, cells isolated from rats previously fed a diet containing 2.0 p.p.m. Se had a reduced occurrence of the two major anti dihydrodiol epoxide adducts. The depression in DMBA binding following selenite supplementation, both in vitro and in vivo, supports the ability of Se to inhibit the initiation phase of carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

[PARTICLE--an expert system for microscopic image analysis].

The pathologist is usually not an expert in engineering or image analysis. Therefore an expert system was developed, entitled PARTICLE, to help pathologists producing image analysis programs in histological pathology. The PARTICLE expert system is based on karyometric data using the AMBA/R dialogue and programming system.

Expert Systems↗
PubMed1988

Automated histometry in fibrocystic breast disease.

Ductal epithelial proliferations of the mammary gland in biopsy material from 101 patients, including 52 with proliferative fibrocystic disease (mastopathy), were quantitatively analyzed by means of the Robotron A 6471 system together with AMBA/R software. Based on reproducible data obtained for distinct karyometric and histometric features, significant differences were found to exist between epithelial proliferations without atypical hyperplasia (mastopathy II) and those with atypia (mastopathy III). The multiparameter analysis also produced some hints that cases of proliferative mastopathy III can be divided into two groups having different risks of developing carcinoma.

Cell Division↗
PubMed1987

Morphometric and densitometric investigations of protoplasmic astrocytes and neurons in human hepatic encephalopathy.

Morphometric and densitometric evaluations were made of nuclei of astrocytes and nerve cells of 49 cases with chronic liver diseases and of 9 control cases. The data measured from Nissl-stained specimens of putamen were compared with clinical degrees of encephalopathy and with blood ammonia levels. The parameters measured included nuclear area and optical density of nuclei. The nuclear area of astrocytes (AAREA), on average, was found to grow significantly along with aggravation of encephalopathy, that growth being from 39 micron 2 in the control group to about 60 micron 2 in cases of severe encephalopathy. Furthermore the proportion of astrocyte nuclei with an area above 70 micron 2 (ALRG) and the proportion of the optical light area of the total nuclear area (AHOLE) rises. Mean compactness (ACEXT) and mean extinction of astrocyte nuclei (AMEXT) dropped along with growing severity of encephalopathy. Mean blood ammonia levels rose from 42 mumol/l in cases with no microscopically detectable signs of encephalopathy to about six times higher values in cases with severe encephalopathy. Optical density of astrocyte nuclei was negatively correlated and mean nuclear area positively correlated to blood ammonia levels. No characteristic morphometric and densitometric changes of nerve cell nuclei were recordable from the putamen.

Adolescent↗