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S Wamberg

Publications and source records attributed to S Wamberg.

36 records · Page 2Linked to original sources
PubMed1996

Acid-base status and cardiovascular function in mink (Mustela vison) anaesthetized with ketamine/midazolam.

Heart rate, arterial blood pressure and blood acid-base status were determined in 18 adult female mink (mean (+/- SEM) body weight 1052 +/- 34 g) during long-term anaesthesia with either controlled ventilation (n=12) or spontaneous respiration (n=6). Surgical anaesthesia was induced by intramuscular injection of ketamine hydrochloride (Ketaminol Vet, 40.0 +/- 1.7 mg/kg) and midazolam hydrochloride (Dormicum 2.8 +/- 0.1 mg/kg) and maintained for at least 5 h by continuous intravenous infusion of this drug combination in 0.9% saline. For all animals, the mean rates of infusion of ketamine and midazolam were 48.4 +/- 1.6 and 1.61 +/- 0.12 mg/h, respectively. Following continuous infusion of the anaesthetics in isotonic saline, at a rate of 20 ml/h, a moderate 'dilution acidosis' developed, which could be corrected by replacement of part of the saline with sodium bicarbonate to a final concentration of approximately 25 mmol NaHCO3 per litre. However, when the animals were allowed to breathe spontaneously, an increase in heart rate and a combined respiratory and metabolic acidosis occurred, due to severe respiratory depression. Apart from these effects and a few cases of increased salivation, no adverse effects over time were observed on the arterial blood acid-base status and cardiovascular function of the animals during ketamine/midazolam anaesthesia. It is concluded that the procedure described for long-term anaesthesia in mink is convenient and safe for acute physiological experiments in this species, provided normal body temperature and pulmonary gas exchange is sufficiently maintained. Thus, the need for an adequately controlled artificial ventilation is strongly emphasized. Finally, a proposal for the composition of an intravenous solution, containing ketamine and midazolam hydrochloride, and sodium bicarbonate in saline, suitable for long-term anaesthesia in adult mink is presented.

Acid-Base Equilibrium↗
PubMed1996

Incidence of nursing sickness and biochemical observations in lactating mink with and without dietary salt supplementation.

The impact of dietary sodium on the incidence of nursing sickness in mink dams and on the average litter biomass of 28 and 42 day old kits was studied. One group (n = 115 including 12 barren females) was given a standard feed mixture with a natural content of 0.53 g NaCl/MJ and another group (n = 115 including 8 barren females) was given the same feed mixture supplemented with NaCl to a final content of 1.00 g/MJ. The average dam weight at weaning was significantly lower (P < 0.001) and the incidence of nursing sickness during the last part of the lactation period 3 times higher in the nonsupplemented group. The average litter biomass at weaning did not differ between the 2 experimental groups. A number of biochemical markers of preclinical nursing sickness, e.g. plasma aldosterone and osmolality, Na+ and Cl concentrations in plasma and urine, were studied during the last part of the lactation period and at weaning in 20 dams of the nonsupplemented group, in 10 dams of the salt supplemented group and, for comparison, in 5 + 5 barren females on the day corresponding to day 34 after parturition in nursing mink. The nonsupplemented group had significantly lower concentrations of sodium and chloride in plasma and urine and a significantly higher concentration of plasma aldosterone as compared to the salt supplemented group. Distinct signs of relative salt deficiency and preclinical nursing sickness thus characterized the nonsupplemented group throughout this period, while more blurred hints of electrolyte imbalances were noticed in the sodium chloride supplemented group at weaning. A beneficial effect of salt supplementation on the incidence of nursing sickness was shown; however, it remains unclear whether salt deficiency can cause nursing sickness or whether salt acts as an appetite stimulant preventing inanition and the development of the disorder.

Aldosterone↗
PubMed1996

Failure of loop diuretics to induce nursing sickness in mink at weaning.

Nursing sickness in mink is thought to be precipitated by inadequate salt intake, whether this is due to inadequate salt levels in the diet or inadequate total dietary intake. To test this hypothesis, lactating females raising large litters were given 2 daily intramuscular injections of the loop diuretic furosemide (Lasix, 4 + 4 mg/kg/day) for 2.5 d during the normal weaning period 6 wk after parturition or served as untreated controls. Following the same protocol, barren mink (i.e. unsuccessfully mated females) were treated similarly. Dams were carefully inspected for clinical signs of nursing sickness during and after the treatment. Urinary osmolality and concentrations of sodium, potassium, chloride, creatinine and carbamide (urea) were measured prior to treatment (day 1) and on day 3, immediately before and 4 h after the final diuretic treatment. Plasma concentrations of aldosterone and cortisol were determined by radioimmunassay 4 h after the last injection with furosemide on day 3. Biochemical changes in urine (a low osmolality, low concentrations of carbamide and creatinine, and extremely low sodium concentrations) and in plasma (aldosteronism) similar to those found in nursing sickness were elicited in the nursing dams. Nevertheless, none of the dams developed overt clinical signs of nursing sickness. It is concluded that the biochemical signs of volume and salt depletion associated with nursing sickness are sequelae rather than etiological factors of this disorder.

Aldosterone↗
PubMed1994

Rates of heat and water loss in female mink (Mustela vison) measured by direct calorimetry.

The energy expenditure (EE) of adult female mink was studied by continuous 24-hr measurement of rates of total heat loss (THL) in a controlled environment using a 24 m3 calorimeter allowing separate on-line determination of sensitive (SHL) and evaporative (EHL) heat loss within the range of 20-200 W (72-720 kJ/hr). In four adult female mink (scanblack colour mutant), studied in transparent cages and given free access to feline food pellets and water, the mean 24-hr energy expenditure (= THL) under controlled experimental conditions was 8.9 W/kg (range: 5.5-13.1 W/kg) at 18 degrees C and 5.8 W/kg (range: 4.3-9.5 W/kg) at 24 degrees C. The results are in agreement with the data reported in the literature on the metabolic rate of adult farm-raised mink, calculated from rates of oxygen uptake under controlled experimental conditions, and with the energy requirement for maintenance, 586 kJ/kg/day (6.8 W/kg) recommended by the NRC. Under the experimental conditions of the present study the mean rate of total evaporative water loss (TEWL) amounted to 3.7 g/kg/hr at 18 degrees C and 5.5 g/kg/hr at 24 degrees C. The contributions of SHL and EHL to 24-hr THL in female mink were inversely related and markedly dependent on chamber temperature. When corrected for evaporated urinary and faecal water, SHL and EHL amounted to 76 and 24% of THL at 18 degrees C, but at 24 degrees C the corresponding values were 41 and 59%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Influence of dietary sources of fat on lipid synthesis in mink (Mustela vison) mammary tissue.

1. The fatty acid composition of the triglyceride fraction of mink milk sampled during mid-lactation (day 28 post partum) from two nursing mink was compared to that of plasma samples and to the fatty acid composition of the feed rations used. 2. Chemical analysis of the triglyceride composition of mink milk demonstrated only minute concentrations of fatty acids with a chain length below C14. 3. The saturated C16:0- and C18:0-unit fatty acids in mink milk made up for 24-40% of the total amount of fatty acids extracted, the remainder being represented by mono and polyunsaturated long-chain (C16-C24) fatty acids. 4. Preliminary in vitro experiments proved the incorporation of 14C-labelled glucose, acetate or palmitate into triacylglycerols in cultures of mink mammary tissue to be linear for at least 2 hr. 5. The in vitro capacity for de novo fatty acid synthesis in mink mammary tissue using 14C-labelled glucose or acetate was low, i.e. ranging from 0.096-0.109 nmol/g (fresh tissue)/min, and amounted to only about 5% of that obtained in the case of [14C]palmitic acid incubation. 6. Following 14C-labelled acetic or palmitic acid incubation of mink mammary tissue neither desaturation nor chain elongation was observed. 7. In response to long-term feeding on rations with two different sources of animal fat (F = fish oil or L = lard) the influence of compositional changes in dietary neutral lipids on the fatty acid composition of the lipids of mink milk is discussed.

Animals↗
PubMed1992

Nursing sickness in lactating mink (Mustela vison). I. Epidemiological and pathological observations.

In a retrospective survey, the epidemiological characteristics of nursing sickness in Standard Black and Pastel mink (Mustela vison) were examined in a Danish fur research farm. Based on the clinical diagnosis of the disease, the overall morbidity in a total of 1774 lactating females amounted to 14.4% and the case fatality rate to 7.8%. Apparently healthy females weaned an average of 5.0 kits per litter, while dams suffering from nursing sickness raised and weaned an average of 5.4 kits per litter (p less than 0.01). Based on logistic regression analysis, the increasing age of the lactating dam, followed by littersize and female weight loss, appeared to be major determinants for the development of nursing sickness. The impact of additional covariates such as litter weight gain and female color type were remarkably low. At weaning (day 43) the mean individual live weight of the kits of either sex did not differ between healthy and sick dams. In Standard Black, the total biomass of the offspring raised by sick dams was significantly larger than that of the healthy controls (p less than 0.01). During the final two weeks of lactation, apparently healthy dams lost on average 14% of their body mass, whereas those affected by nursing sickness had a mean weight loss of about 31% (p less than 0.001). Postmortem examination of 25 dams with severe nursing sickness verified the clinical findings of progressive dehydration and emaciation. The gastrointestinal tract was empty and gastric ulcers and melaena were frequently present. Other common findings included small livers,enlarged adrenals and pitted kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1992

Nursing sickness in lactating mink (Mustela vison). II. Pathophysiology and changes in body fluid composition.

An investigation of the pathophysiological characteristics of nursing sickness in mink was carried out as a follow-up study of a previous epidemiological survey at a Danish fur research farm during the 1989 breeding season. In a total of 48 nursing females of the Standard Black and Pastel type, concentrations of several pertinent biochemical constituents of whole blood, plasma, urine and skeletal muscle were determined in order to identify nutritional and metabolic factors involved in the origin and development of the disease. Compared to the reference data obtained in 17 apparently normal lactating dams the findings in 31 females suffering from nursing sickness presented varying clinical and biochemical signs of progressive dehydration and emaciation: aldosteronism, hypovolemia, hyponatremia, hyperkalemia (in the face of muscle potassium depletion), hyperglycemia and azotemic acidemia. Neither ketosis nor severe lactacidemia was observed. The urine was almost devoid of sodium and chloride, and urinary potassium concentration diminished by approximately 50%. The concentrating ability of the kidneys was reduced to less than one third of the maximum value. The results were consistent with severe dehydration and emaciation due to heavy losses of energy, water and body mass along with increasing milk production. The progressive nature of the disease supported the hypothesis that nursing sickness is due to the combined effects of heavy milk production and excessive tissue catabolism along with reduced or ceased dietary intake, and maybe increasing environmental stress. In the advanced stage of the disease coma and death appear to be the inevitable outcome of the metabolic strains for continuing milk production.

Acid-Base Equilibrium↗
PubMed1988

Adrenocorticotropic hormone in the control of renal tubular hydrogen ion secretion. Balance of non-metabolizable base in ACTH-stimulated weanling rats subject to acid or base loading.

Groups of weanling rats subject to ACTH-stimulation (tetracosactrin, 1 mg kg-1 day-1) were exposed to heavy oral loads of ammonium chloride (approx. 21 mmol kg-1 day-1) or sodium bicarbonate (approx. 40 mmol kg-1 day-1) for 8 days. During loading with sodium bicarbonate, the animals maintained a normal positive external (whole body) balance of non-metabolizable base (NB), excess NB being excreted quantitatively in the urine, whereas loading with ammonium chloride caused a fall in the mean balance of NB from a reference value of 12.1 mmol per 8 days to about zero. However, in the two groups the concentration in plasma of NB rose from the reference value (41 mmol l-1) to the same level (57 and 59 mmol l-1, respectively; P greater than 0.5) despite extreme differences in rates of gastrointestinal NB absorption, despite a significant rise in the rate of endogenous sulphuric acid production and despite the presence of ample chloride in diet and urine. These results indicate that ACTH determines the extracellular concentration of NB at which exchange of NB takes place by influencing, directly or indirectly, the relative rates of renal tubular H- secretion and Cl- reabsorption at any given rate of tubular reabsorption of Na-. Some cybernetic considerations of the disturbance are presented.

Acid-Base Equilibrium↗
PubMed1987

Methionine-induced acidosis in the weanling rat.

Whole body balances of non-metabolizable base (NB) were studied in weanling rats fed a cereal-based diet with or without added L-methionine. In response to L-methionine loading (2.5 mmol day-1) the rats exhibited a significant reduction in rates of food intake (109 vs. 160 g per 8 days) and body growth (3 vs. 52 g per 8 days); fractional oxidation of absorbed dietary amino acid sulphur increased from 0.28 to 0.64; and mean urinary sulphate excretion increased from 2.3 to 14.8 mmol per 8 days. Mean rates of renal excretion of NB and filtered titratable organic acid decreased from 20 to -11 mmol per 8 days and from 22 to 8 mmol per 8 days. Balances of calcium and NB remained at reference values despite a decrease in whole blood 'base excess' from -1.0 to -6.4 mmol l-1. The concentration of NB in plasma rose but slightly. It is concluded that L-methionine loading in the weanling rat leads to extracellular non-carbonic acidosis subject to renal compensation. This acidosis is due not to retention of H+ released by ionization of endogenous sulphuric acid but possibly to accumulation of (acid) organic metabolites of methionine which are efficiently conserved by the kidneys. The rise in sulphuric acid production leads to an adaptive decrease in fractional reabsorption of filtered sulphate. Even during inhibited growth, absorbed dietary NB is retained and deposited in the skeleton, probably as calcium carbonate.

Acid-Base Equilibrium↗
PubMed1985

Acid-base balance in ruminating calves given sodium hydroxide-treated straw.

1. Studies of whole-body balances of non-metabolizable base (NB) and several minerals, and of relevant acid-base quantities in blood and urine, were carried out in two 6-month-old ruminating Holstein X Friesian bull calves fed on fixed rations containing 500 g barley straw/kg diet (group A) to examine the quantitatively important components of the balance of NB and determine the rates of mineral and NB retention associated with normal body growth. 2. Parallel balance studies were conducted in six other bull calves given fixed rations containing 500 g alkali-treated barley straw/kg diet to evaluate the effects of long-term alkali-straw feeding on the rates of body growth and skeletal mineral and NB deposition and the renal control of extracellular electrolyte and acid-base status. The straw component was treated either with 50 g sodium hydroxide/kg dry matter (DM) (group B; two calves), or with 50 g or 100 g NaOH/kg DM and subsequently neutralized with hydrochloric acid (groups C and D, two calves per group). In all groups the animals were given free access to tap water. 3. Throughout the total 105 d experiment, all animals remained healthy and gained weight. Normal body growth group A) was associated with a positive balance of NB (1-2 mmol/kg live weight (LW) per d) due to continuing deposition of dietary NB in 'new tissue', largely in the developing skeleton. 4. During 105 d alkali-straw feeding, the animals showed a remarkable ability to cope with dietary loads of NAOH or sodium chloride, up to about 30 mmol/kg LW per d, without any significant disturbance of extracellular acid-base and electrolyte status or body growth rate. The surplus mineral and NB loads were absorbed and subsequently excreted in an increased volume of urine. Rates of mineral and NB retention were not significantly different from the reference values of group A and remained within the range of values reported from similar studies. In all groups, maintenance of normal whole blood and plasma acid-base and electrolyte status was accounted for by efficient renal control of the composition of the extracellular fluid compartment.

Acid-Base Equilibrium↗
PubMed1983

Corticotropin-induced alkalosis in the weanling rat and its relation to the balance of non-metabolizable base.

Studies of whole body balances of non-metabolizable base (NB) and several electrolytes and of the acid-base status of blood and urine during development of corticotropin-induced alkalosis in the weanling rat were carried out in order to identify the primary source of base and factors instrumental in maintenance of the alkalotic state. The data were compared to baseline and running control values and to the results of whole carcass analysers. Primary accumulation of NB was accounted for by ongoing gastrointestinal NB absorption in the weight-losing animal, distributed to extracellular and non-extracellular compartments of the body. An increase in the rate of renal excretion of non-metabolizable acid (NA), from negative values to zero, corresponded to an increased load of endogenous sulphuric acid and a reduced rate of gastrointestinal NB absorption. Accordingly, the renal response did not per se contribute to the induction of extracellular alkalosis. Maintenance of alkalosis occurred in spite of ample chloride in the renal tubular lumen and a moderate increase in relative extracellular volume. In the absence of evidence of overloading (with base) or malfunction of the kidney, corticotropin-induced alkalosis is classifiable as a 'set-point disturbance' of acid-base metabolism in which fluctuations in the (non-renal) load of NA lead to commensurate changes in renal NA excretion at an elevated extracellular pH. Withdrawal of corticotropin injections was followed by prompt restoration of a normal extracellular acid-base status and a return to reference values for renal NA excretion despite a marked fall in the balance of NB. This observation supports a concept of the extracellular compartment as the immediate reference system of the kidney.

Acid-Base Imbalance↗
PubMed1979

Balance of net base in the rat: adaptation to and recovery from sustained hypercapnia.

Net base and mineral balances were evaluated in a group of male 350 g Wistar rats exposed to 10% carbon dioxide in air for 10 days with a view to identifying the source of net base subject to retention during renal compensation of sustained respiratory acidosis. In response to hypercapnia, the rate of renal net acid excretion rose but insignificantly. However, a rise in whole body net base concentration from about 215 mmol/kg to about 250 mmol/kg came about by ongoing gastrointestinal absorption in the weight-losing animal, absorbed net base being distributed to extracellular and non-extracellular compartments of the body, presumably including bone. During an 8-day recovery period, a small decrement in whole body net base concentration was observed.

Acid-Base Equilibrium↗
PubMed1979

Balance of net base in the rat. V. Effects of oral ammonium chloride loading.

The physiology of oral ammonium chloride loading was studied in four groups of male weanling rats weighing about 100 g and fed either standard ground Rostock rat food (containing 317 mmol net base/kg) or ground barley (containing only 20 mmol net base/kg). One group of animals on the Rostock diet received oral supplements of ammonium chloride (approximately 32 mmol . kg-1 . day-1) sufficient to provide a net zero rate of oral net base intake. In this group, ongoing fecal net base excretion caused net acid to be absorbed at an average rate of 15 mmol . kg-1 . day-1. The mean rate of renal net acid excretion rose markedly (by 29.4 mmol . kg-1 . day-1); and over an 8-day balance period the animals were able to maintain near-normal balances of net base. During a subsequent 8-day recovery the pattern of mineral turnover returned to normal. Even in the barley-fed rats, gastrointestinal net acid absorption was observed. These animals suffered a 61% reduction in the rate of body growth, but the overall rate of net base retention, per kilogram of mass gain, was close to the reference value. Finally, the combination of barley and ammonium chloride led to weight loss, positive net acid balances (8.5 mmol . kg-1 . day-1), and a maximal rate of renal net acid excretion (50.8 mmol . kg-1 . day-1). Some implications for the metabolism of organic acids are discussed.

Acid-Base Equilibrium↗
PubMed1978

Balance of net base in the rat. III. Effects of oral sodium bicarbonate and sodium citrate loading.

The balance of net base in groups of male weanling Wistar rats exposed to sustained oral loads of net base were studied. In response to dietary loads of sodium bicarbonate (approx. 50 mmol.kg-1.day-1) an average increment in the mean rate of retention of net base of 21.8 mmol.kg-1.day-1 was observed in the absence of significant changes in the blood 'base excess'. Following withdrawal of sodium bicarbonate, mean rates of gastrointestinal absorption, renal excretion, and retention of net base promptly returned to control values, accumulated net base being retained in the body, presumably as skeletal sodium carbonate. In response to equimolar loads of net base in the form of trisodium citrate, a similar, albeit less pronounced, rise in the rate of retention of net base occurred.

Acid-Base Equilibrium↗
PubMed1978

Balance of net base in the rat. IV. Effects of oral calcium and phosphate loading.

Mineral and net base balances were studied in groups of male weanling Wistar rats given oral loads of calcium chloride, monocalcium phosphate plus monosodium phosphate, and disodium phosphate plus monopotassium phosphate, respectively. A group of adult nongrowing rats loaded with calcium chloride was included for comparison. In response to CaCl2 loading, gastrointestinal net base absorption was inhibited due, largely, to luminal precipitation of tertiary phosphates of calcium and magnesium. In the weanling animal, however, a rise in the rate of renal net acid excretion matched the concomitant decrement in the rate of net base absorption, permitting of continued skeletal net base storage. Similarly, in the adult animals augmented renal net acid excretion offset a positive rate of gastrointestinal net acid absorption with a resultant (normal) zero net base balance. Loading with monocalcium phosphate and disodium phosphate at a constant oral net base intake did not influence the overall net base balance, but disodium phosphate loading caused significant sodium retention.

Acid-Base Equilibrium↗
PubMedDate not supplied

LH release in mink (Mustela vison). Pattern of the LH surge and effect of metabolic status.

The mink is a seasonal breeder with induced ovulation and delayed implantation. Reproductive processes are strongly influenced by energy supply and body condition. Items for which there is paucity or complete lack of data were the main objectives of this study: the temporal relationship between copulation and the pre-ovulatory LH surge and the influence of energy supply on LH release. A total of 30 yearling female mink with a well defined metabolic status was used. Twelve females kept in the laboratory were measured in six consecutive one-week balance periods each including the measurement of heat production by means of indirect calorimetry, and 18 females were kept under conventional farm conditions. The animals were fed so as to maintain energy balance (CON), flush fed by 2 weeks food restriction followed by 2 weeks refeeding (FLUSH), or kept in a negative energy balance (NEG). Plasma concentrations of the thyroid hormones, IGF-1 and insulin were determined weekly (n = 12), or 1 week after change in energy supply to the FLUSH group (n = 18). On the day of mating, blood samples for LH and oestradiol-17beta (E2) were taken before and immediately after mating and then 4, 8, 12, 24, 30 and 48 h thereafter. Frequent blood samplings, each lasting 60 min, were taken during the LH surge from two other females surgically fitted with venous access ports. Peak concentrations of LH were recorded on the first sampling, an average 16 min after mating. The concentrations remained elevated for 12 h, but almost decreased to basal values 24 h after mating. Plasma E2 was high before mating and peak values were attained 4 h after mating after which it decreased. Energy supply had no significant influence on LH and E2, but there was a tendency for a more sluggish LH release in NEG animals. The lack of response in FLUSH animals was explained by these animals having a lower intake of metabolisable energy than CON animals, the total intake not being significantly different from the NEG group. Plasma concentrations of thyroid hormones, IGF-1 and insulin were not significantly affected by the treatment, but in FLUSH animals the values mirrored energy supply, and in the NEG group, the values tended to decrease during the course of the experiment. It was concluded that the pre-ovulatory LH surge is an immediate response to mating, and that reproductive activity in the mink is maintained over a wide range of energy supply and body condition.

Animals↗