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Biomedical subjects

J M Naylor

Publications and source records attributed to J M Naylor.

At least 37 records · Page 2Linked to original sources
PubMed1995

cDNA cloning, expression, and chromosomal localization of a human UDP-GalNAc:polypeptide, N-acetylgalactosaminyltransferase.

Oligonucleotide primers derived from the cDNA encoding a full-length bovine UDP-GalNAc:polypeptide, N-acetylgalactosaminyltransferase (GalNAc-transferase) [Homa, F. L., Hollander, T., Lehman, D. J., Thomsen, D. R., and Elhammer, A. P. (1993) J. Biol. Chem. 268, 12609-12616], were used for PCR to isolate sequences encoding a homologous enzyme from human salivary gland cDNA. Comparison of the human and bovine nucleotide sequences reveals 94.8% sequence identity in their coding regions and 87% identity in their 3-untranslated regions. The translation of the human GalNAc-transferase coding region predicts an amino acid sequence which is nearly identical (99.6%) to that of the bovine counterpart; there are five conservative and one non-conservative amino acid substitutions between the two enzymes. Expression of the bovine and human cDNAs in the insect cell line, Sf9, resulted in the synthesis of proteins which appeared identical on SDS-PAGE and which had similar enzymatic properties. Screening of a somatic cell human/rodent hybrid panel with a probe derived from the human GaLNAc-transferase cDNA sequence indicated that the human GalNAc-transferase gene is localized to chromosome 18.

Amino Acid Sequence↗
PubMed1995

Effect of psyllium on plasma concentration of glucose, breath hydrogen concentration, and fecal composition in calves with diarrhea treated orally with electrolyte solutions.

We investigated the effect of adding psyllium to a standard electrolyte solution in 10 calves with diarrhea. The calves were tested with the standard solution on one day and standard solution plus psyllium on the alternate day. The order of treatments was randomized. Psyllium converted the solution into mucilage, but did not affect fecal consistency. Mean +/- SEM area under the glucose absorption curve was lower for mucilaginous than for nonmucilaginous solutions, 2.1 +/- 0.62 vs 3.75 +/- 1.18 mmol.h, respectively, but the difference was not significant. The area under the breath hydrogen curve was marginally lower for mucilaginous than nonmucilaginous solutions, 102 +/- 20 and 209 +/- 60 ppm.h, respectively. The usefulness of such decreased bacterial fermentation is doubtful.

Analysis of Variance↗
PubMed1994

Selection of quarter horses affected with hyperkalemic periodic paralysis by show judges.

Thirty offspring of a Quarter Horse sire, affected by hyperkalemic periodic paralysis (HPP), were examined electromyographically. On the basis of the detection of or lack of spontaneous activity with high frequency myotonic or pseudomyotonic discharges, the horses were diagnosed as being affected (14 horses) or unaffected (16 horses) with HPP. The show performance of these horses was evaluated for the first 3 to 9 years of their life by use of American Quarter Horse Association records. Horses affected with HPP performed significantly (P < 0.01) better in halter classes than did unaffected horses; mean halter points for the 2 groups were 11.9 and 0.4, respectively. The mean total performance points were not significantly different. None of the offspring had a successful racing record.

Animals↗
PubMed1994

Equine hyperkalemic periodic paralysis: review and implications.

The purpose of this review is to present an up-to-date summary of the signs, diagnosis, treatment, and implications of equine hyperkalemic periodic paralysis. The review encompasses all original articles published between 1986 and early 1993. Hyperkalemic periodic paralysis is the result of a genetic mutation in the skeletal muscle sodium channel gene. It is inherited as an autosomal dominant trait; most affected horses are heterozygotes. The classical signs are muscle fasciculation, spasm, and weakness associated with hyperkalemia. However, these signs are only rarely observed in affected horses. Potential sequelae to attacks are abrasions and involuntary recumbency; these problems are not specific for hyperkalemic periodic paralysis, but they occur more frequently in hyperkalemic periodic paralysis-affected horses. It is also likely that hyperkalemic periodic paralysis results in greater muscle mass. There are suggestions that homozygotes may be more severely affected and show signs of upper respiratory obstruction as foals. The practitioner needs to be aware of the tests for hyperkalemic periodic paralysis, and their limitations, so that he can properly diagnose this condition. The industry has the difficult problem of deciding whether or not testing should be mandatory and the fate of positive horses.

Animals↗
PubMed1993

Clinical syndrome and diagnosis of hyperkalaemic periodic paralysis in quarter horses.

Of the 16 horses studied, 14 belonged to a family previously shown to be susceptible to hyperkalaemic periodic paralysis (HPP), and 8 were shown to have HPP. Diagnosis of HPP by electromyographic detection of myotonic discharges or by oral administration of KCl to induce clinical signs and hyperkalaemia had similar reliability and gave the same result in 80% of cases. KCl had to be administered at doses up to 0.2 g/kg bodyweight to produce signs in some horses. KCl challenge testing was more time consuming than EMG and resulted in one fatality. Overall, electromyography and potassium challenge testing together gave the most accurate diagnosis. Horses were more likely to manifest signs of HPP if they were immature. There was no sex predisposition. The most frequent sign of HPP was muscle fasciculation. Other signs were sweating, muscle spasm, and weakness. Respiratory rate increased greatly during some attacks. Attacks of muscle fasciculation without hyperkalaemia were observed in 2 HPP-affected horses. Affected horses had a greater frequency of spontaneous clinical abnormalities, due mainly to trailering problems, traumatic abrasions and episodes of continuous muscle fasciculation. Hyperkalaemia was confirmed in only one of these instances.

Age Factors↗
PubMed1993

Determination of lactose and xylose malabsorption in preruminant diarrheic calves.

In preliminary studies feeding the poorly absorbed carbohydrate sorbitol at 2.3 g/kg body weight as an indication of maximal fermentative capacity failed to produce the expected large increase in breath hydrogen excretion but did produce a transient diarrhea in five out of six control calves. Twelve healthy control and eighteen diarrheic calves were fed lactose or D-xylose on consecutive days at 1.15 g/kg body weight and a concentration of 46 g/L. Breath and blood samples were collected at 1 h intervals from 0 to 7 h. After administration of lactose, there was a significant increase in breath hydrogen excretion in diarrheic versus control calves. The increase in plasma glucose concentrations was delayed in diarrheic calves but the area under the absorption curve was similar in control and diarrheic calves. After administration of D-xylose, breath hydrogen excretion did not increase significantly but plasma D-xylose concentrations were significantly reduced in diarrheic calves. The pathogens commonly isolated from the feces were Cryptosporidium species, rotavirus and coronavirus. The number of pathogens and the severity of the calves' acid-base deficit were not related to the severity of carbohydrate malabsorption. Decreased absorption of lactose and D-xylose may be the result of intestinal villous atrophy caused by viral or parasite infection. It was concluded that carbohydrate malabsorption rather than a specific lactose maldigestion is a significant problem in diarrheic calves. Diarrheic calves appear to digest and absorb lactose when fed in small amounts.

Animals↗
PubMed1992

Effects of electrolyte solutions for oral administration on clotting of milk.

The effect of electrolyte solutions commercially formulated for oral administration on clotting of milk was investigated in vitro. Rennet or abomasal fluid was used as the clotting agent. Electrolyte solutions that contained large amounts of bicarbonate or citrate (greater than 40 mEq/L) had marked adverse effects on milk clotting, probably because bicarbonate increased pH and because citrate chelated calcium. Addition of solutions that did not contain alkalinizing agents resulted in normal or enhanced clotting, and enhancement was associated with the presence of acid phosphate salts. Electrolyte solutions that included acetate as the alkalinizing agent did not interfere with milk clotting as long as pH of the final solution was acidic and minimal amounts of citric acid salts were present (less than 10 mEq/L). Acetate-containing electrolyte solutions can be used for oral administration in calves in which alkalinization of blood without interference with milk clotting is desired.

Abomasum↗
PubMed1992

Familial incidence of hyperkalemic periodic paralysis in quarter horses.

The pedigrees of 17 horses with hyperkalemic paralysis were studied. All were first-, second-, or third-generation offspring of a common sire, 16 were registered Quarter Horses. Analysis indicated that it was unlikely that the concentration of hyperkalemic periodic paralysis in the offspring of this sire was attributable to chance. The familial nature of this condition should help veterinarians diagnostically. It also suggests that it is possible to reduce the incidence of this condition by breeding from non-affected lines of horses and reinforces the need for studies to determine whether the disease is genetic in origin. Although more affected horses were second-generation offspring, the proportion of horses affected was largest in the first generation and decreased progressively with each generation. This is probably because horses in the earlier generations have been observed for longer periods and thus clinical signs are more likely to have been noticed in these horses.

Animals↗
PubMed1992

Inheritance of myotonic discharges in American quarter horses and the relationship to hyperkalemic periodic paralysis.

Electromyography (EMG) was used to detect myotonic discharges in Quarter Horse breeding stock and to follow the results of mating horses with hyperkalemic periodic paralysis (HPP). The studies were performed on two brood mare farms. A total of six breeding stock showed myotonic discharges and 15 were nonmyotonic. Myotonic discharges were seen in five of six horses belonging to the blood line previously implicated as being predisposed to HPP. Two of these horses had shown clinical signs of HPP. Only one of 15 breeding horses unrelated to the HPP predisposed blood line showed myotonic discharges. When both parents were non-myotonic on EMG than the F1 generation (n = 6) were also nonmyotonic. When a stallion with HPP and myotonic discharges was mated to eight nonmyotonic mares over a six year period half the animals of the F1 generation (n = 25) showed myotonic discharges. When both parents showed myotonic discharges four F1 offspring were myotonic and two were nonmyotonic on EMG testing. There was no evidence of sex linkage. The results are consistent with an autosomal dominant mode of inheritance. Hyperkalemic periodic paralysis and myotonic discharges on EMG may be different manifestations of the same underlying defect.

Animals↗
PubMed1990

Oral fluid therapy in neonatal ruminants and swine.

Definitive recommendations regarding the best method to treat the diarrheic calf cannot be made at this time. The exact recommendation will probably depend on the situation. At the present time, I do not believe it is detrimental to withdraw milk from the diet for periods up to 24 to 36 hours, as long as the calf is in good condition and is returned to a full ration (maintenance plus) of milk within 3 to 5 days from the start of milk withdrawal. Milk withdrawal is most likely to be beneficial in those situations in which the calf is depressed and has lost its sucking reflex. Oral electrolyte solutions should be fed at the rate of 4-6 L/day if diarrhea is profuse or if the calf is depressed. As the calf feels better and the severity of diarrhea decreases, the amount of oral electrolyte solution can be reduced. It is sensible to continue feeding oral electrolyte solution, perhaps at the rate of 2 L/day, as long as the calf scours. Products containing 40-80 mEq/L of alkalizing agent give the best results. The higher concentrations may be more effective in older calves. Products containing bicarbonate or metabolizable base can be used when the calf is held off milk, whereas only solutions that contain a metabolizable base should be used if the calf is fed milk that day. Milk withdrawal may only be beneficial in calves that are losing their interest in sucking. Early reintroduction to milk and avoidance of milk deprivation in bright calves will help maintain condition and may boost immune function and mucosal repair. Calves that are held off milk for more than 2 days and calves that are deprived of milk while in poor condition should be fed a high-energy electrolyte solution. Beef calves tend to be treated while they are still on the dam, and if they are separated from the cow, it is usually only for a short period. This maintains the cow's lactation and maternal instincts. Cow's milk is better digested than many milk replacers and is available at a steady rate because calves suck frequently. Calves maintained on cow's milk should be fed an oral electrolyte solution containing a metabolizable base. Gastric fill from the electrolyte solution will tend to reduce milk consumption. It is important to prevent the calf from gorging on milk, which sometimes happens when a calf that is depressed and not sucking regains its appetite and has access to a very full udder. Cows that have been separated from their calf or that have distended udders should be milked out.

Animals↗
PubMed1990

Use of electromyography for the diagnosis of equine hyperkalemic periodic paresis.

The use of electromyography (EMG) as a diagnostic aid for equine hyperkalemic periodic paresis (EHPP) was investigated in seven affected and seven control horses. Affected horses were confirmed positive for EHPP either by elevated serum potassium concentration with clinical signs of myotonia, or by inducing hyperkalemia and clinical signs using oral potassium chloride challenge. All horses were asymptomatic at the time EMG was performed, using bipolar fine wire needle electrodes. The myopotentials were recorded on magnetic tape and displayed on paper charts for analysis. Insertional and resting activity were recorded from the right supraspinatus, triceps, extensor carpi radialis and gluteal muscles in standing horses. Myotonic discharges were seen in six of seven affected horses but not in any of the controls. All seven affected horses and two control horses had prolonged insertional activity. Five out of seven affected horses and one control horse displayed spontaneous motor unit discharges unrelated to recording electrode movement. Myoelectrical potentials containing closely timed muscle potentials, i.e. doublets, were found in all affected horses, with four of seven affected horses also showing triplets. These potentials were not observed in any of the controls. No obvious difference in activity was observed among the four muscle sites tested. It is concluded that EMG is a safe and useful tool for diagnosing EHPP in horses not currently displaying clinical signs. Myotonic discharges and doublets appear to be the most diagnostically significant electromyographic abnormalities in EHPP affected horses.

Animals↗
PubMed1990

Risk factors for mortality from diarrhea in beef calves in Alberta.

A case-study involving 56 randomly selected beef herds in Alberta was conducted to assess the association of a number of suspected risk factors upon the odds of a high mortality from diarrhea among calves less than 30 days of age. Using stepwise logistic regression it was found that an increased percentage of heifers calving in the herd, poor drainage in the nursing area, providing limited shelter in the nursing area, a large calving area, and wintering cows and heifers on the same ground were conditionally associated with an increase in the odds of high mortality from neonatal diarrhea.

Alberta↗
PubMed1989

The effects of feeding milk to diarrheic calves supplemented with oral electrolytes.

The effects of feeding different levels of milk to diarrheic calves (n = 19) supplemented with oral electrolytes were investigated. In the early stages of the disease the calves were fed either enough milk to maintain normal growth in a healthy calf, one half that volume or no milk. The three groups were further subdivided according to whether or not the electrolyte solution contained bicarbonate. A full milk ration allowed uninterrupted weight gains of 1% body weight/day (p = 0.003), but caused greater inappetence (p = 0.003 to 0.037) at the beginning of the trial than lower levels of milk intake. Electrolyte solutions with bicarbonate reduced growth rates in milk fed calves (p = 0.014). The density of fat stores increased with the level of milk feeding (p = 0.04 to 0.053). The mitotic index of the duodenal mucosa increased with milk feeding (p = 0.08), indicating a superior mucosal regeneration potential. Thymic atrophy was pronounced in those calves fed no milk (p = 0.001). It was concluded that the continued feeding of milk to diarrheic calves was beneficial. Electrolyte solutions containing bicarbonate should be avoided when milk is fed to diarrheic calves.

Animals↗
PubMed1989

Clinical and pathological effects of flunixin meglumine administration to neonatal foals.

The effects of daily intravenous administration of flunixin meglumine at dosages of 0.55, 1.1, 2.2 and 6.6 mg/kg for five days were examined in neonatal foals. Six two day old foals were used to evaluate the effect of each dosage. Foals were examined every day and blood samples collected on days 1, 3 and 6. All foals were euthanized after six days, necropsied and examined for lesions. The major clinical abnormality was diarrhea, but the incidence was not related to the dosage of flunixin meglumine administered. The foals receiving 6.6 mg/kg of flunixin meglumine had significantly more gastrointestinal ulceration and greater cecal pathology and cecal petechiation scores than those foals treated with saline. The foals in the 6.6 mg/kg treatment group had a greater loss of total protein during the study, but the difference was not significant. There were no statistically significant blood cellular or biochemical alterations associated with the administration of flunixin meglumine. There were no significant clinicopathological differences between healthy foals treated with the recommended dosage of flunixin meglumine and those treated with physiological saline.

Animals↗
PubMed1989

Diagnosis of copper deficiency and effects of supplementation in beef cows.

The effects of feeding supplementary dietary copper to a herd of 400 beef cows, were studied over a two year period. In the first year of the trial, the calves showed clinical signs of copper deficiency. There was improved growth following subcutaneous injection of copper ethylenediamine tetraacetate, and the treated calves had a 2.8% increase in adjusted weaning weights. In the second year of the trial pregnant cows were fed a basal ration of bromegrass silage, barley and minerals over the winter feeding period. The feed was supplemented with copper so that half received 5.5 mg/kg of copper on a dry matter basis and half 40 mg/kg. Calving occurred in the spring and half the calves were treated with injectable copper at birth and again at 12 weeks of age. There was no evidence of copper deficiency in the calves and there was no effect of high level copper supplementation on calf birth weight, or neutrophil candidacidal activity. Susceptibility to diarrhea varied in a complex fashion; morbidity was lowest in calves born to dams fed supplementary copper and highest in calves born to supplemented dams and injected with copper at birth. The cows and calves grazed the same copper deficient pasture over the summer. The average daily gain for calves born to supplemented cows was 0.999 +/- 0.010 kg/day (x +/- SEM) which was significantly greater than the 0.972 +/- 0.009 kg/day for calves from nonsupplemented dams (p = 0.044). The benefit of copper supplementation on 200 day weaning weight was estimated at 4.8 kg. Evidence of copper deficiency was seen when a herd test showed mean serum levels below 9 mumol/L and liver values below 0.09 mmol/kg wet matter.

Animals↗