Biomedical subjects

J K Ha

Publications and source records attributed to J K Ha.

10 recordsLinked to original sources

PubMed2006

Electron spin precession upon reflecting from ferromagnetic surfaces.

Electrons with the polarization vector perpendicular to the magnetization of Fe, Co, and Ni films are spin analyzed after reflecting from the ferromagnet. At low primary electron energies a strong spin motion is found, namely, a precession of the polarization around the magnetization and a change of the angle between the polarization and the magnetization. This observation can be accounted for by the existence of spin-dependent gaps in the electronic band structure of the ferromagnets.

Journal Article↗

PubMed2005

Effect of germination temperature on characteristics of phytase production from barley.

The effects of germination temperature on the growth of barley seedlings for phytase production were studied at 15, 20 and 25 degrees C for 6-10 days. The growth rate of the barley seedlings was increased as the germination temperature was increased. The initial rate of total protein production was closely coupled to that of the barley growth, and the rate of total protein production tended to increase as the germination temperature was increased. SDS-PAGE analysis of total protein from the barley seedlings showed time-dependent appearance and disappearance of protein bands. Although no significant phytase activity was detected at zero time of germination, a significant increase in phytase activity up to 7.9-fold occurred during the first several days of germination then decreased. Phosphate production (viz. phytate degradation) in the barley seedlings occurred rapidly at the beginning of germination. However, the rate of production continued to decrease with further germination. A time lag of about 1-2 days between the rate of total protein production and that of phytase production was observed. Unlike the extent of total protein production, that of phytase production was similar irrespective of germination temperature. Partial purification of a crude enzyme extract by hydrophobic interaction chromatography resulted in two phytase fractions (PI and PII). Zymogram analysis demonstrated that PI had two bands with molecular masses of about 66 and 123 kDa while PII had one band corresponding to a molecular mass of about 96 kDa. The optimal temperature for PI was found to be 55 degrees C, while it was 50 degrees C for PII. The enzyme fraction PI had a pH optimum at 6.0, whereas the optimum pH for PII was found to be 5.0. Addition of 0.1% (v/v) Tween 80 was found to increase enzyme activity significantly (i.e., 167% for PI and 137% for PII). Phytate in cereals including barley, rice, corn and soybean degraded effectively by the treatment of the barley phytases.

6-Phytase↗

PubMed2002

Influence of slaughter weight and sex on yield and quality grades of Hanwoo (Korean native cattle) carcasses.

To assess the effects of slaughter weight and sex on APGS (Animal Products Grading Service) quality and APGS yield grade of Korean Hanwoo (n = 20,881) cattle, data were collected from cow, bull, and steer carcasses during a 1-yr period. Factors used to determine quality grade (marbling, meat color, fat color, texture, and overall maturity score) and yield grade (cold carcass weight, adjusted fat thickness, and longissimus muscle area) by the Korean grading system were recorded. Both yield and quality grades were improved (P < 0.01) with heavier slaughter weight, but there was no difference in yield grade for Hanwoo cattle classes heavier than 551 kg (P > 0.01). Longissimus muscle area, adjusted fat thickness, and marbling score increased (P < 0.01) with carcass weight. Bull carcasses showed higher yield but lower quality than those of cows or steers (P < 0.01). The quality grade of steer carcasses was higher (P < 0.01) than that of cow carcasses due to higher marbling scores, lower maturity scores, and heavier carcass weights. Hanwoo carcasses with larger longissimus muscle areas in relation to their carcass weight had lower APGS quality grades. The APGS quality grades were different between yield grade A and B carcasses (P < 0.01), but quality grade was not improved by increased fat thickness beyond the point of yield grade B. Adjusted fat thickness and marbling score showed significant (P < 0.01) differences among all yield grade classes, and this resulted in increased quality grade as yield grade decreased. Adjusted fat thickness showed the strongest correlation (r = -0.63) with yield grade, whereas marbling score had the strongest correlation (r = 0.81) with quality grade. Results showed a negative effect of castration on yield but a positive effect on quality. Also, data showed that Hanwoo carcasses with heavier weights had higher quality grades than those of lighter weight.

Animals↗

PubMed2001

The effects of sequential inoculation of mixed rumen protozoa on the degradation of orchard grass cell walls by anaerobic fungus Anaeromyces mucronatus 543.

The effects of protozoa on the degradation of plant cell walls (CW) during different growth stages of the fungus Anaeromyces mucronatus have been investigated. Since fungi show a marked lag in their in vitro cultures and many protozoa rapidly die during a prolonged incubation time, the effects of protozoa may vary according to the growth phase of the fungi. Therefore, the approach adopted was (i) to inoculate CW with fungus monoculture, (ii) to inoculate CW with fungus-protozoa coculture, or (iii) to sequentially inoculate fungal cultures that had been grown in CW for 24 (initial stage of growth), 48, and 72 h (late stage of growth) with mixed protozoa. When a fungus was associated with protozoa, a growth phase dependent effect was observed. Ruminal protozoa adversely affected the growth and activity when introduced in the initial growth stage of A. mucronatus, but a synergetic interaction was detected when added to late growth stage cultures. Although there is no immediate explanation for these results, the data suggested that protozoa can engulf the fungal zoospores, which are in ruminal fluids and (or) attached to small feed particles, but cannot engulf the fungal thallus that is tightly attached to feed particles by a rhizoidal system. Our data indicated that the protozoa did not influence cellulolysis by the fungi in exponential and (or) stationary phase, but they had a marked inhibitory effect on fungi that were in lag phase. Inhibition during lag phase could result from the protozoal predation of fungal zoospores that had failed to attach to substrates.

Anaerobiosis↗

PubMed2001

Survival and prognostic factors in patients with primary pulmonary hypertension.

OBJECTIVES: Primary pulmonary hypertension (PPH) that affects predominantly young and productive people is a progressive fatal disease of unknown cause. The objectives of this study were to characterize mortality in patients with PPH and to investigate the factors associated with their survival. METHODS: Thirteen patients with PPH were enrolled between 1988 and 1996 and followed-up through July 1999. Measurements at diagnosis included hemodynamic and pulmonary function variables in addition to information on demographic data and medical history. RESULTS: 1) The mean age of the patients with PPH enrolled into the study was 36.1 +/- 9.3 years with female predominance. 2) The estimated median survival was 3.4 +/- 0.6 years. 3) Decreased cardiac index was the only significant predictor of mortality (Cox proportional hazards model). CONCLUSION: Patients with PPH have a poor survival expectancy. In this limited study with a small number of patients, mortality is largely associated with decreased cardiac index.

Adult↗

PubMed2000

Relative contributions of bacteria, protozoa, and fungi to in vitro degradation of orchard grass cell walls and their interactions.

To assess the relative contributions of microbial groups (bacteria, protozoa, and fungi) in rumen fluids to the overall process of plant cell wall digestion in the rumen, representatives of these groups were selected by physical and chemical treatments of whole rumen fluid and used to construct an artificial rumen ecosystem. Physical treatments involved homogenization, centrifugation, filtration, and heat sterilization. Chemical treatments involved the addition of antibiotics and various chemicals to rumen fluid. To evaluate the potential activity and relative contribution to degradation of cell walls by specific microbial groups, the following fractions were prepared: a positive system (whole ruminal fluid), a bacterial (B) system, a protozoal (P) system, a fungal (F) system, and a negative system (cell-free rumen fluid). To assess the interactions between specific microbial fractions, mixed cultures (B+P, B+F, and P+F systems) were also assigned. Patterns of degradation due to the various treatments resulted in three distinct groups of data based on the degradation rate of cell wall material and on cell wall-degrading enzyme activities. The order of degradation was as follows: positive and F systems > B system > negative and P systems. Therefore, fungal activity was responsible for most of the cell wall degradation. Cell wall degradation by the anaerobic bacterial fraction was significantly less than by the fungal fraction, and the protozoal fraction failed to grow under the conditions used. In general, in the mixed culture systems the coculture systems demonstrated a decrease in cellulolysis compared with that of the monoculture systems. When one microbial fraction was associated with another microbial fraction, two types of results were obtained. The protozoal fraction inhibited cellulolysis of cell wall material by both the bacterial and the fungal fractions, while in the coculture between the bacterial fraction and the fungal fraction a synergistic interaction was detected.

Animals↗

PubMed1993

Release of volatile branched-chain and other fatty acids from ruminant milk fats by various lipases.

Bovine, ovine, and caprine milk fats were treated with pregastric lipases (kid goat, calf, and lamb), microbial lipases (Candida cylindracea, C. cylindracea AY30, Aspergillus niger APF12, Rhizopus arrhizus, Penicillium roqueforti R10, and Mucor zavanicus Map 10), porcine pancreatic lipase, or milk lipase. All three pregastric lipases preferentially hydrolyzed volatile branched-chain and short n-chain fatty acids from each milk fat. Pregastric lipases also released a relatively low proportion of C10 from bovine milk fats but a high proportion of C10 from caprine milk fat. Milk lipase released very low concentrations of butanoic acid and did not release 4-methyloctanoic acid in significant amounts except from caprine milk fat. Ovine milk fat yielded a substantially greater concentration of butanoic acid than did bovine or caprine milk fats when it was hydrolyzed by porcine pancreatic lipase. Candida cylindracea lipase yielded high amounts of volatile n-chain fatty acids nonselectively and only small quantities of volatile branched-chain fatty acids. High amounts of the medium-chain branched fatty acids were produced by kid goat, P. roqueforti, A. niger, and R. arrhizus lipases.

Animals↗

PubMed1988

Digestion and utilization of high moisture barley by lactating dairy cows.

Two experiments were conducted to study digestion and utilization of dry and high moisture barley. Dry matter yield of dry barley was 2.99 tonnes/ha in contrast to 3.58 tonnes/ha for high moisture barley. In Experiment 1, 38 cows in early to midlactation were assigned to two diets (40% alfalfa hay; 9.4% supplement and 50.6% barley, DM basis) that differed only in the type of barley fed: diet 1, rolled dry barley, and diet 2, rolled high moisture barley. Although DM intake, milk yield, and 4% FCM were not significantly influenced by diet, cows fed diet 2 had higher milk persistency than those fed diet 1. In Experiment 2, three lactating cows fitted with ruminal and duodenal cannulae were assigned to three dietary treatments in a Latin square design. Diets 1 and 2 were as in Experiment 1, whereas diet 3 contained ground high moisture barley. Digestibility coefficients tended to be lower and duodenal starch percent higher for cows fed diet 3 than those fed diets 1 or 2. No significant dietary differences were observed in ruminal pH, VFA, or ammonia concentrations. Although ensiling and processing influenced the rate and extent of DM and CP degradation in situ, treatment did not influence effective degradability. Results suggest that the feeding value of high moisture barley for lactating cows is equivalent to dry barley on a DM basis.

Animal Feed↗

PubMed1984

Effect of protein on nutrient digestion and milk production by Holstein cows.

Four multiparious Holstein cows fitted with ruminal and duodenal cannulae were in a 4 X 4 Latin square experiment to assess effects of increasing dietary protein on ruminal blood and duodenal traits, milk production, and nutrient digestion. Protein percents of 13, 15, 17, and 19 dry matter were achieved by rolled barley replaced with 0, 12, 24, and 36% rapeseed (canola) meal in pelleted concentrate mixtures. Increasing dietary protein concentration increased ruminal ammonia nitrogen, urea nitrogen in blood serum, and concentration of duodenal total, nonammonia, and feed nitrogen. Highest microbial nitrogen concentration was in cows fed the 15% protein diet; ruminal ammonia nitrogen was 6 mg/100 ml at this percent of protein. Cows fed 13% protein lost body weight (.43 kg/day), whereas those at 15, 17, and 19% protein gained .59, .38, and .59 kg/day. Efficiency of conversion of feed protein to milk protein declined, but digestibility of dry matter, organic matter, and nitrogen was improved with increasing dietary protein. From the traits measured, 15% crude protein appeared to be optimum for cows producing an average of 28 kg milk per day.

Animals↗

PubMed1983

In vitro effect of pH variations on rumen fermentation, and in vivo effects of buffers in lambs before and after adaptation to high concentrate diets.

An in vitro wheat fermentation study (Exp. 1) was conducted to investigate the effect of pH (pH 7, 6, 5 and 4) on rumen lactate and VFA production. In another study (Exp. 2), lambs were fed high concentrate diets containing either no additions (control), 2% sodium bentonite, 2% limestone, 2% NaHCO3 or 10% alfalfa hay. The effect of these diets was determined on ruminal and systemic measurements before and after dietary adaptation. Effect of the control, bentonite, limestone and NaHCO3 treatments on nutrient digestibilities and mineral retentions after adaptation were also determined. Lactate production in the rumen fluid incubated at pH 7 or 6 was negligible. Reducing incubation pH from 6 to 5 resulted in accumulation of both total and L(+)-lactate, but further reduction to pH 4 did not result in an additional increase in lactate production. Variations in incubation pH or time did not affect the ratio of D to L isomers. Lowering the incubation pH to below 6 reduced total VFA production and increased the acetate to propionate ratio. In Exp. 2, the feeding of buffers or alfalfa hay was effective in maintaining a more normal feed intake and ruminal pH, and reduced ruminal lactate. Blood measurements were not affected by dietary treatment. When animals were adapted to the experimental diets, the dietary buffers did not influence rumen and blood measurements. Lambs fed 2% NaHCO3 digested more (P less than .05) organic matter, crude protein, N-free extract and starch, and 2% limestone increased (P less than .05) fiber digestibility. Dietary buffers tended to increase fecal pH and reduce fecal starch Magnesium retention with 2% bentonite, Ca retention with 2% limestone and Na and Mg retention with NaHCO3 were all increased (P less than .05).

Animals↗