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Y Gröhn

Publications and source records attributed to Y Gröhn.

18 recordsLinked to original sources
PubMed2006

Multilocus sequence typing supports the hypothesis that cow- and human-associated Salmonella isolates represent distinct and overlapping populations.

A collection of 179 human and 156 bovine clinical Salmonella isolates obtained from across New York state over the course of 1 year was characterized using serotyping and a multilocus sequence typing (MLST) scheme based on the sequencing of three genes (fimA, manB, and mdh). The 335 isolates were differentiated into 52 serotypes and 72 sequence types (STs). Analyses of bovine isolates collected on different farms over time indicated that specific subtypes can persist over time on a given farm; in particular, a number of farms showed evidence for the persistence of a specific Salmonella enterica serotype Newport sequence type. Serotypes and STs were not randomly distributed among human and bovine isolates, and selected serotypes and STs were associated exclusively with either human or bovine sources. A number of common STs were geographically widespread. For example, ST6, which includes isolates representing serotype Typhimurium as well as the emerging serotype 4,5,12:i:-, was found among human and bovine isolates in a number of counties in New York state. Phylogenetic analyses supported the possibility that serotype 4,5,12:i:- is closely related to Salmonella serotype Typhimurium. Salmonella serotype Newport was found to represent two distinct evolutionary lineages that differ in their frequencies among human and bovine isolates. A number of Salmonella isolates carried two copies of manB (33 isolates) or showed small deletion events in fimA (nine isolates); these duplication and deletion events may provide mechanisms for the rapid diversification of Salmonella surface molecules. We conclude that the combined use of an economical three-gene MLST scheme and serotyping can provide considerable new insights into the evolution and transmission of Salmonella.

Animals↗
PubMed1992

The mediating effect of maternal nutrition knowledge on the association between maternal schooling and child nutritional status in Lesotho.

The present study tested whether maternal nutrition knowledge was a mediating factor in the association between maternal schooling and child nutritional status, and whether the mechanism involved differed according to socioeconomic status. The data were collected in Lesotho on 921 mother-child pairs and included scores from a nutrition knowledge test, socioeconomic and demographic information, and the child's anthropometric data. A wealth factor derived from a factor analysis was used to stratify the sample into two socioeconomic groups. Two-stage least-squares estimation was used to test the mediating role of nutrition knowledge between maternal schooling and child weight-for-age. Results showed that both the importance of maternal schooling and the mechanism by which it affects the child's weight-for-age are contingent upon the family's socioeconomic status. While maternal schooling was positively associated with weight-for-age for both wealthier and poorer households, the size of the effect was much larger for the latter group. The effect of maternal schooling on weight-for-age was mediated by the mother's nutrition knowledge only among wealthier households. These results imply that, in Lesotho, nutrition education for mothers could contribute to improving children's growth, but only in households that have access to a minimum level of resources. For poorer households, nutrition education would not be sufficient.

Adult↗
PubMed1987

Nonlinear pharmacokinetics and conversion to glucose of intravenous sodium propionate in dairy cattle.

Three doses of sodium propionate (.75, 1.5, and 3.0 mmol/kg) were administered intravenously to 6, 8, and 14 dairy cows. Using first order kinetic analysis, the apparent plasma half-life increased significantly with increasing propionate dose. The apparent increase of propionate half-life with increasing propionate dose was attributed to saturation of uptake and disposal mechanisms. Using the nonlinear mathematical model of Henri-Michaelis-Menten for propionate concentrations at 3.0 mmol/kg, propionate half-life was significantly shorter than that obtained with the first order kinetic model. The Michaelis constant was 4.0 mM, the maximal rate of concentration decrease was .55 mM/min, half-life was 4.8 min, and distribution volume was .37 L/kg. Plasma glucose concentrations increased following all doses of propionate. The maximal increase in glucose concentration occurred earliest for the lowest dose and latest for the highest dose and increased in magnitude with increasing propionate dose. The plasma glucose response to intravenous propionate has been suggested as a measure of liver function in ruminants. Of the three propionate doses tested, the 3.0 mmol/kg dose appeared to saturate the uptake and disposal mechanisms of healthy liver and should be the most satisfactory dose for observing the plasma glucose response to injected propionate.

Animals↗
PubMed1986

Structure and occurrence of perisinusoidal stellate cells in the liver of lactating dairy cows.

The structure and occurrence of liver stellate cells were studied in healthy, mildly and severely ketotic lactating dairy cows. In addition, the stellate cells in five clinically healthy lactating cows, each sampled at five different occasions after parturition, were studied. Liver samples were obtained by percutaneous needle biopsy, immediately fixed in 3% glutaraldehyde and processed for light and electron microscopy. The volume fractions of stellate cells and hepatocytic fat were estimated. Bovine stellate cells contained one, often large lipid droplet, not surrounded by a membrane. The cells had a well-developed Golgi apparatus and rough endoplasmic reticulum. Morphological indications for collagen synthesis by the cells were found. The results also suggest that a direct exchange of material between hepatocytes and stellate cells is possible. The volume fraction of stellate cells was decreased and the fraction of hepatocytic fat increased in severely ketotic cows as compared to the other groups. A negative correlation between the volume fractions of hepatocytic fat and stellate cells was significant. Hepatocytic fat decreased significantly after parturition, but an increase in the volume fraction of stellate cells was not significant.

Animals↗
PubMed1986

Hepatic morphology and effects of intravenous injection of sodium propionate on plasma propionate and glucose in fed and fasted dairy cattle.

Sodium propionate (3 mmol/kg) was injected IV into 8 nonlactating dairy cows before and after 6 days (144 hours) of fasting. During fasting, long-chain fatty acids in plasma increased from 0.30 +/- 0.05 (SE) mM to 1.09 +/- 0.15 mM (P less than 0.05). Liver fat increased from 0.5 +/- 0.3% to 9.3 +/- 1.7% (P less than 0.05). Half-life of injected sodium propionate increased significantly (P less than 0.05) from 7.6 +/- 0.5 minutes to 10.1 +/- 1.0 minutes during fasting. Sulfobromophthalein half-life did not change significantly (3.8 +/- 0.79 minutes to 5.3 +/- 1.3 minutes). Increases in plasma glucose concentrations after propionate loading were significantly less during fasting than during feeding. Thus, the change in glucose concentration served as an indicator of hepatic conversion of propionate to glucose. Increases in glucose concentration of less than 2 mM at 30 minutes after propionate loading indicated that liver function was altered in nonlactating dairy cows.

Animals↗
PubMed1985

Ultrastructural changes of the liver in spontaneously ketotic cows.

The ultrastructure of the liver in normal, mildly ketotic and severely ketotic cows was studied using stereological methods. In the liver of severely ketotic cows there is: (1) a significant increase in the volume fraction of hepatocytes and a decrease in the volume fraction of sinusoids, and (2) an increase in the volume fraction of lipid and smooth endoplasmic reticulum and a decrease in the volume fraction of glycogen and Golgi in parenchyma. A decrease in the profile density of mitochondria per 1 mm2 field and an increase of the volume occupied by mitochondria were not significant nor was the decrease in the volume density of rough endoplasmic reticulum. The degree and duration of negative energy balance obviously affect the morphological changes of the fatty liver. However, additional work is needed to determine the significance of ultrastructural changes in liver function.

Acidosis↗
PubMed1985

Propionate loading test for liver function during experimental liver necrosis in sheep.

The first objective of this work was to study the conversion of propionate to glucose by liver of the sheep during experimentally induced liver necrosis. An additional objective was to determine the most appropriate sampling time after a propionate load has been given to use glucose concentration as an aid in the diagnosis of disturbed liver function. Sodium propionate (3 mmol/kg) was injected IV into 6 healthy sheep before and after they were given carbon tetrachloride (20% CCl4 in mineral oil; 0.25 ml of CCl4/kg, orally). To differentiate the effects of liver necrosis from the effects of decrease in food intake after CCl4 administration, 5 sheep which were fasted for 2 days, but not given CCl4, were studied. Microscopically, liver necrosis was observed, as well as an increase of fatty infiltration in nonnecrotic liver tissue. After sheep were given CCl4, the plasma liver-specific enzyme activities (namely, those of iditol dehydrogenase and gamma-glutamyl-transferase) were elevated. Microscopic and enzymatic changes were not observed in fasted animals. Serum sulfobromophthalein (BSP) half-life (t1/2) was markedly increased in the sheep given CCl4 treatment (t1/2 = 22.8 +/- 11 minutes) when compared with the t1/2 before treatment (t1/2 = 2.5 +/- 0.2 minutes). The BSP t1/2 did not differ between fed and fasted sheep. The t1/2 of the IV propionate load increased significantly, from 6.9 +/- 0.4 minutes in the control sheep to 12.8 +/- 2 minutes in the CCl4-treated sheep, whereas an insignificant increase was seen after fasting (6.8 +/- 1 minutes to 8.3 +/- 1 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Propionate loading test for liver function in spontaneously ketotic dairy cows.

Propionate utilisation by the liver in spontaneously ketotic dairy cows was investigated by determining blood glucose levels after an intravenous sodium propionate load (2.5 mmol kg-1). In addition, blood ketone body concentrations were measured after propionate loading. Cows were divided into three groups (control, mildly ketotic and severely ketotic) by their blood acetoacetate concentrations. Plasma glucose concentrations increased significantly after sodium propionate injection in all three groups (P less than 0.05). The maximum glucose concentration occurred earlier in the control group than in the ketotic groups. Changes in glucose concentrations following propionate loading of control and ketotic cows differed significantly at 20 minutes and beyond. Differences in the change in glucose concentration between mildly ketotic and severely ketotic cows were not significant. Acetoacetate concentration was significantly decreased at five minutes and beyond after the injection in ketotic cows, whereas beta-hydroxybutyrate concentration decreased more slowly. A decrease in beta-hydroxybutyrate concentration was significant at 40 minutes and beyond in the severely ketotic group and at 10 minutes and beyond in the mildly ketotic group after loading.

3-Hydroxybutyric Acid↗
PubMed1983

Fatty infiltration of liver in spontaneously ketotic dairy cows.

The purpose of this study was to ascertain 1) fatty infiltration of the liver in spontaneously ketotic cows and 2) the most appropriate blood components to aid diagnosis of ketotic fatty liver. Liver biopsies and blood samples were obtained under field conditions. Cows were divided into three groups (healthy, mildly ketotic, and severely ketotic) by their blood ketone body concentrations. Severely ketotic cows had a greater percent fat in the liver than healthy cows. The mildly ketotic group fell between the other two groups and was significantly different from only the severely ketotic group. There was a positive correlation between fatty infiltration and blood ketone body concentrations but a negative correlation with glucose concentrations. Liver-specific enzymes were positively correlated with fatty infiltration. Only ornithine carbamoyltransferase and iditol (sorbitol) dehydrogenase could be used to separate healthy cows from those with severe ketosis. The best equation to explain the variation of percent fat in liver included concentration of beta-hydroxybutyrate (BHB) and logarithm of ornithine carbamoyltransferase concentration (Log-OCT): % Fat = -6.15 + 2.39 (BHB) + 11.7 (LogOCT) Although this equation explained 39.5% of the variation, it could not be used to predict reliably percent fat in the liver. Liver biopsy seems still to be the only reliable method of measuring of fatty infiltration in the liver.

3-Hydroxybutyric Acid↗