Biomedical subjects

K A Howard

Publications and source records attributed to K A Howard.

4 recordsLinked to original sources

PubMed1990

The effect of an adaptation period to soybean oil additions in the diets of young pigs.

Utilization of soybean oil (SBO) in swine starter diets and the effect of an adaptation period to SBO on performance was studied in two 4-wk experiments with pigs initially 4 to 5 wk of age. One trial was extended an additional 4 wk and apparent DE was measured during the 4th wk postweaning. Corn-soybean meal-based diets were used in which SBO was substituted for cornstarch at 2, 4 and 6% of the diet in Exp. 1 and at 3 and 6% of the diet in Exp. 2. In Exp. 2, SBO was added either initially (adaptation) or after 2 wk (no adaptation). In Exp. 1 daily gain and efficiency of feed utilization were improved (P less than .05) by adding SBO during wk 3 and 4, but not earlier. Feed intake was not affected by treatment. In Exp. 2, for the initial 4-wk postweaning period, there was no effect of SBO addition on growth rate; feed intake was depressed (P less than .05) when SBO was added at wk 3, and efficiency of feed utilization was improved (P less than .05) for pigs fed SBO without an adaptation period. The primary improvements in performance occurred in the 3rd and 4th wk postweaning, with a tendency for pigs to perform better without an adaptation period. During wk 4, pigs adapted to SBO consumed more (P less than .05) feed but tended to be less efficient (P less than .10) than nonadapted pigs. With or without adaptation, apparent DE was unaffected by SBO additions. Regardless of adaptation period, SBO additions depressed feed intake (P less than .05) and improved efficiency of feed utilization (P less than .01) for the 5- to 8-wk growing phase. In conclusion, adding SBO the first 2 wk postweaning did not improve performance; an adaptation period was not necessary for a performance response from added SBO.

Adaptation, Physiological↗

PubMed1986

Cloning the DdeI restriction-modification system using a two-step method.

DdeI, a Type II restriction-modification system from the gram-negative anaerobic bacterium Desulfovibrio desulfuricans, recognizes the sequence CTNAG. The system has been cloned into E. coli in two steps. First the methylase gene was cloned into pBR322 and a derivative expressing higher levels was constructed. Then the endonuclease gene was located by Southern blot analyses; BamHI fragments large enough to contain the gene were cloned into pACYC184, introduced into a host containing the methylase gene, and screened for endonuclease activity. Both genes are stably maintained in E. coli on separate but compatible plasmids. The DdeI methylase is shown to be a cytosine methylase. DdeI methylase clones decrease in viability as methylation activity increases in E. coli RR1 (our original cloning strain). Therefore the DdeI system has been cloned and maintained in ER1467, a new E. coli cloning strain engineered to accept cytosine methylases. Finally, it has been demonstrated that a very high level of methylation was necessary in the DdeI system for successful introduction of the active endonuclease gene into E. coli.

Bacteriophage lambda↗

PubMed1985

Nucleotide sequence of the PaeR7 restriction/modification system and partial characterization of its protein products.

Bal31 deletion experiments on clones of the PaeR7 restriction-modification system from Pseudomonas aeruginosa demonstrate that it is arranged as an operon, with the methylase gene preceding the endonuclease gene. The DNA sequence of this operon agrees with in vitro transcription-translation assays which predict proteins of 532 amino acids, Mr = 59,260 daltons, and 246 amino acids, Mr = 27,280 daltons, coincident with the methylase and endonuclease genes, respectively. These predicted values coincide with the measured molecular weights of the purified, denatured PaeR7 endonuclease and methylase proteins. The first twenty amino acids from the amino-terminus of the purified endonuclease exactly match those predicted from the DNA sequence. Finally, potential regulatory mechanisms for the expression of phage restriction are described based on the properties of several PaeR7 subclones.

Amino Acid Sequence↗

PubMed1978

Efficacy and acceptability of injectable medroxyprogesterone. A comparison of 3-monthly and 6-monthly regimens.

Five hundred Black Rhodesian women given injections of 150 mg Depo-Provera every 3 months (group A) and 500 women given an injection of 450 mg Depo-Provera every 6 months (group B) were reviewed after 6 months. Group B had a significantly lower rate of defaulters. There was no significant difference between the groups with regard to weight gain, systolic and diastolic blood pressure increase, overall abnormal bleeding patterns and complaints of side-effects. Among those women who reported abnormal bleeding patterns, significantly more in group B had amenorrhoea. There was no significant increase of prolonged bleeding in group B. Among those women who complained of side-effects, significantly more in group B complained of headaches and a bloated abdomen. No pregnancies occurred in either group. The increased annual cost of the 450 mg injections, which was the main reason for women not accepting this regimen, is outweighed by convenience and reduced travel costs. Depo-Provera 450 mg given by 6-monthly injection is well tolerated and effective, and appears to be even more satisfactory as regards continued acceptance than 150 mg given every 3 months.

Adult↗