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Biomedical subjects

D D Johnson

Publications and source records attributed to D D Johnson.

At least 19 recordsLinked to original sources
PubMed1998

A practical approach to laparoscopic surgery for malfunctioning peritoneal dialysis catheters.

Peritoneal dialysis is widely accepted for the chronic management of end-stage renal disease but is associated with as high as a 70% complication rate including a significant problem with peritoneal dialysis catheter flow obstruction. The application of laparoscopic surgical techniques has revolutionized the surgical approach to peritoneal dialysis catheter-related dysfunction. However, the specific laparoscopic surgical technique varied among the reported literature. This lack of a standard laparoscopic surgical approach to obstructed peritoneal dialysis catheters prompted us to review and compare our specific technique and experience in 17 patients with 10 recent reported series. We specifically examined for insufflation techniques, access port placements and closures, timing postoperatively for reinstituting peritoneal dialysis, wound complications, and overall long-term success rates for peritoneal dialysis catheter salvage.

Adult↗
PubMed1998

Hereditary haemochromatosis mutation frequencies in the general population.

OBJECTIVES: This study aims to expand our knowledge of the general population frequency of two mutations, C282Y and H63D, identified in the candidate gene for hereditary haemochromatosis, and to determine whether the testing can be performed using routinely obtained cheek-brush (buccal) samples. SETTING: Banked buccal lysate samples, randomised and coded for anonymity, from a cohort of couples who underwent prenatal cystic fibrosis screening in Maine. METHODS: A multiplex ARMS test was performed on buccal cell lysates to identify the two mutations. RESULTS: Genotype frequencies found among the 1001 subjects studied (502 women, 499 men) were: seven C282Y homozygotes, 22 C282Y/H63D compound heterozygotes, 97 C282Y heterozygotes, 17 H63D homozygotes, 246 H63D heterozygotes, and 612 individuals with no detectable mutation. The allele frequencies for C282Y and H63D were 0.066 and 0.151, respectively. CONCLUSIONS: Observed genotype frequencies in Maine are consistent with expectations and with consensus data from five smaller studies. Combined mutational analysis data indicate that homozygosity for C282Y (the genotype found in about 85% of subjects with diagnosed hereditary haemochromatosis) occurs in 51 per 10,000 white subjects of northern European heritage; the corresponding total hereditary haemochromatosis prevalence of about 60 per 10,000 is consistent with previous estimates. The study also confirms that H63D would not be useful in general population screening for hereditary haemochromatosis.

Cohort Studies↗
PubMed1998

Effects of supplemental vitamin E and canola oil on tissue tocopherol and liver fatty acid profile of finishing swine.

We conducted a 4 x 3 factorial experiment with finishing pigs for 6 wk to evaluate effects of dietary canola oil and vitamin E on vitamin E status and liver fatty acid profile. Treatments consisted of four supplemental levels of vitamin E (0, 50, 125, and 200 mg/kg) and three of canola oil (0, 5, and 10% of the diet). Serum was collected each week and tissue samples at d 42. Dietary canola oil (P = .02) and vitamin E (P < .001) increased serum alpha-tocopherol. Serum alpha-tocopherol reached a plateau at d 35 of vitamin E and canola oil supplementation. An interaction was observed between canola oil and vitamin E (P = .02) for liver alpha-tocopherol. Liver alpha-tocopherol was greater in pigs fed diets with 10% canola oil and supplemented with 125 or 200 mg/kg of vitamin E than in pigs fed diets with 0 and 5% canola oil. An interaction also occurred between canola oil and vitamin E (P = .01) for alpha-tocopherol in the gluteus medius and obliquus capitis caudalis muscles. A greater magnitude of increase in muscle alpha-tocopherol was observed in pigs fed diets with no canola oil than in pigs fed diets with 5 and 10% canola oil. Highest alpha-tocopherol was in liver, followed by obliquus capitis caudalis and then gluteus medius. Inclusion of 5 or 10% dietary canola oil decreased the amount of saturated fatty acids by 4.1 and 13.5%, increased monounsaturated fatty acids by 10.9 and 39.3%, respectively, and had no effect (P > .10) on total polyunsaturated fatty acids. Canola oil increased linoleic acid [18:2(n-6)] (quadratic, P = .05) and linolenic acid [18:3(n-3)] (linear, P < .001) while decreasing arachidonic acid [20:4(n-6)] and docosadienoic acid (20:2) linearly (P < .001 and P = .02, respectively). Dietary canola oil and vitamin E increased serum and tissue alpha-tocopherol; canola oil increased monounsaturated and decreased saturated fatty acids in liver.

Animals↗
PubMed1997

Effect of three hours of hypoxia on atrial natriuretic factor gene expression in the ovine fetal heart.

OBJECTIVES: The current study investigated the effects of 3 hours of hypoxia on atrial natriuretic factor gene expression and peptide content in each of the four cardiac chambers of the near-term ovine fetus. STUDY DESIGN: Twenty-three chronically catheterized ovine fetuses at 125 to 129 days' gestation (term 145 days) were used for this study. Fetal hypoxia was induced for 3 hours in 12 fetuses by infusion of nitrogen into the maternal trachea. The remaining fetuses were used as controls. Fetal arterial PO2 and plasma atrial natriuretic factor concentrations were measured during hypoxia. At the end of the hypoxic period atrial natriuretic factor peptide contents and messenger ribonucleic acid levels in each cardiac chamber were determined by radioimmunoassay and Northern blot analysis, respectively. RESULTS: With infusion of nitrogen into the maternal trachea, fetal arterial PO2 was reduced within 30 minutes by an average of 8.0 +/- 0.3 (SEM) mm Hg (p < 0.0001) and remained reduced at this level throughout the entire hypoxic period. Plasma atrial natriuretic factor concentrations increased by 1152 +/- 212 pg/ml (p < 0.003) and the increase was sustained for the duration of hypoxia. Atrial natriuretic factor peptide and messenger ribonucleic acid levels were much higher in the atria than in the ventricles. Hypoxia did not result in alterations of atrial natriuretic factor peptide content or messenger ribonucleic acid abundance in each cardiac chamber. CONCLUSIONS: In the near-term ovine fetus, 3 hours of hypoxia resulted in greatly elevated plasma atrial natriuretic factor concentrations; this response was sustained for the duration of hypoxia. However, the increase was not associated with a detectable change in atrial natriuretic factor peptide content or an induction of atrial natriuretic factor gene expression in the atria and ventricles.

Animals↗
PubMed1997

Is nasogastric tube decompression necessary after major abdominal surgery in children?

Nasogastric (NG) decompression has traditionally been used after major abdominal surgery in pediatric patients. This study was designed to determine if NG tubes could be routinely omitted in pediatric patients undergoing major abdominal procedures. Between January 1993 and December 1995, 83 patients had follow-up prospectively without NG decompression after a variety of major abdominal surgeries. NG tubes were inserted for persistent vomiting or abdominal distension. Exclusion criteria included bowel obstruction, intestinal atresia, and perforation of the stomach or duodenum. Ages ranged from 13 days to 22 years. Seventy-four patients (89%) were treated successfully without postoperative NG decompression. There were no cases of pneumonia, wound dehiscence, anastomotic leak, or delay in return of gastrointestinal function. Nine patients required NG tubes for persistent vomiting or abdominal distension. An anastomotic leak developed in one patient after endorectal pull-through. NG decompression is unnecessary after most major abdominal operations in pediatric patients. The endorectal pull-through may represent a group of patients that benefit from routine decompression.

Adolescent↗
PubMed1997

Three-dimensional ultrasound of the fetal spine.

OBJECTIVE: To describe normal fetal spinal anatomy displayed by three-dimensional ultrasound and to determine whether three-dimensional ultrasound improves visualization of specific spinal defects. METHODS: Fetuses (n = 28) (16 normal and 12 abnormal) were examined on standard two- and three-dimensional sonographic equipment. RESULTS: In 15 of 16 normal fetuses, the spine was visualized at least from the upper thoracic area to the lower sacrum in a single three-dimensional image, and in 14 normal fetuses continuity of the ribs and spine was depicted. Neural tube defects were identified on both two- and three-dimensional ultrasounds; however, three-dimensional ultrasound displayed the level of the defect more accurately in three of the five cases. Scoliosis was recognized easily on a single three-dimensional rendered image, whereas several two-dimensional redered image, whereas several two-dimensional images were needed for the examiner mentally to reconstruct the scoliosis. CONCLUSION: Three-dimensional ultrasound may become an important tool for imaging of the fetal spine. Additional studies are necessary to determine the efficacy and cost effectiveness of this technology. However, our preliminary data suggest that presentation of the spine as a continuous structure rather than in independent two-dimensional views makes visualization of the spatial relationship of the spinal anatomy and adjacent structures easier. The ability to review the volume data using techniques not available on two-dimensional ultrasound may enable physicians to determine the extent of neural tube defects with more accuracy.

Female↗
PubMed1997

False-positive diagnosis of spina bifida in a fetus with triploidy.

BACKGROUND: Neural tube defects can be difficult to diagnose using ultrasound. Cranial markers, such as the lemon and banana signs, are useful sonographic findings that alert the ultrasonographer to examine the spine more carefully. The false-positive rate for the banana sign has been reported previously as zero. CASE: A patient with elevated maternal serum alpha-fetoprotein presented for a fetal ultrasound examination. Findings on the scan included a lemon sign, a banana sign, an effaced cisterna magna, and splayed lumbar vertebrae. After pregnancy termination, no spinal abnormality was detected on autopsy. X-rays of the fetal spine demonstrated narrowing in the thoracic spine. The karyotype of the fetus was 69,XXY. CONCLUSION: The sonographic cranial findings suggestive of a neural tube defect were misleading in this case.

Abortion, Therapeutic↗
PubMed1997

A stereoselective synthesis of 7 alpha-(3-carboxypropyl) estradiol from a noncontrolled substance.

Alkylation of 3,17 beta-bis(2-trimethylsilyl)ethoxymethyl-1,3,5(10) estratriene-6-one (2) with 5-bromo-1-pentene using NaHMDS in THF afforded 3,17 beta-bis(2-trimethylsilyl)ethoxymethyl-7-alpha-(4'pentenyl)-1,3,5(10) estratriene-6-one (3) in excellent stereoselectivity (> 95% epimeric excess). Functionalization of the side chain in compound 3 was accomplished via ozonolysis, oxidation and esterification to give 5 in 72% yield. The reduction of ester (5) using NaBH4 in MeOH afforded the corresponding 6 alpha-hydroxy compound (6) as a single isomer in 72% yield. The hydroxyl group in 6 was removed by converting to the corresponding xanthate (7) followed by reduction using n-Bu3SnH to afford 8 in good yield. Finally, the SEM protective groups in 8 were removed, after which the ester function was hydrolyzed with LiOH to give 7 alpha-(3'-carboxypropyl)estradiol (10), in 10.6% overall yield from 3.

Estradiol↗
PubMed1997

Carcass characteristics, the calpain proteinase system, and aged tenderness of Angus and Brahman crossbred steers.

We used 69 steers of varying percentage Brahman (B) breeding (0% B, n = 11; 25% B, n = 13; 37% B, n = 10; 50% B, n = 12; 75% B, n = 12; 100% B, n = 11) to study the relationship between carcass traits, the calpain proteinase system, and aged meat tenderness in intermediate B crosses. Calpains and calpastatin activities were determined on fresh longissimus muscle samples using anion-exchange chromatography. The USDA yield and quality grade data (24 h) were collected for each carcass. Longissimus steaks were removed and aged for 5 or 14 d for determination of shear force and 5 d for sensory panel evaluation. Even though some yield grade factors were affected by the percentage of B breeding, USDA yield grades did not differ (P > .15) between breed types. Marbling score and USDA quality grade decreased linearly (P < .01) with increasing percentage of B breeding. Shear force after 5 and 14 d of aging was higher (P < .05) in the 100% B steers than in all other breed types, which were not significantly different. Sensory panel tenderness and connective tissue scores decreased linearly (P < .05) with increasing B breeding. A quadratic effect was also noted for tenderness and connective tissue scores; 37% B steers received the highest scores. A similar response was found in mu-calpain activities; the 37% B steers had the highest activities. Conversely, calpastatin activity increased linearly (P < .01) with increasing percentage B breeding. These data show strong linear relationships between calpastatin activity (positive), marbling score (negative), and percentage B breeding, suggesting a possible combined effect of these traits on aged tenderness of intermediate Brahman crosses.

Animals↗
PubMed1997

Consumer evaluation of beef of known categories of tenderness.

A study was conducted to determine consumer perceptions of beef top loin steaks of known shear force and to evaluate how buying trends were modified by the tenderness and price variations of these steaks. Strip loins were cut into a 2.54-cm-thick steaks, and the center steak from each strip loin was used to determine Warner-Bratzler shear force. The remaining steaks were placed into one of the following shear force categories based on that shear force and color-coded accordingly: 1) 2.27 to 3.58 kg (Red); 2) 4.08 to 5.40 kg (White); and 3) 5.90 to 7.21 kg (Blue). Randomly recruited consumers were allowed to evaluate steaks and then purchase steaks based on their findings. A $1.10/kg price difference was placed between each category. Results of the analysis indicated that consumers were able to differentiate between the three categories of tenderness (P < .05). In addition, consumers gave higher (P < .05) juiciness and flavor ratings to Red steaks than to Blue steaks. Overall satisfaction was higher (P < .05) for Red steaks than for the other two categories of steaks. The following percentages of steaks were purchased: 1) Red, 94.6%; 2) White, 3.6%; and 3) Blue, 1.8%. These results suggest that consumers could discern between categories of tenderness and were willing to pay a premium for improved tenderness.

Animals↗
PubMed1997

Predicting the yield and composition of mature cow carcasses.

Cow carcasses (n = 60) were selected based on conformation and external fat to develop more current and useful prediction equations for estimating yield and composition. Adjusted preliminary yield grade was highly correlated to percentage of the carcass as fat (.91), percentage fat in the total lean (.89), and percentage fat in the lean trimmings (.88) of carcasses from non-grain-fed mature cows. Equations for predicting percentage of the carcass as chemical fat had higher -R2 values than equations predicting other compositional end points. The "best" regression equation for predicting total yield (i.e., whole muscle cuts plus lean trimmings adjusted to 10% chemical fat) included hot carcass weight (HCWT), adjusted preliminary yield grade (APYG), longissimus area (LMA), and marbling (MARB), with R2 = .75 and residual standard deviation (RSD) = 2.47. A similar equation predicting total yield from unribbed carcass data included HCWT, APYG, and conformation (CONF) with R2 = .69 and RSD = 3.11. These two equations were applied to a test group of cow carcasses (n = 20), and the average difference between the actual and predicted total yield values from ribbed data and unribbed data was .45 and .83% of HCWT; simple correlations between the actual and predicted values were .74 and .69, respectively. These equations contain relatively simple independent variables to identify and more nearly represent current industry processing practices than equations previously available.

Aging↗
PubMed1996

A technique for the creation of long autogenous tissue arterial patches.

An endarterectomized segment of an occluded artery (e.g. superficial femoral artery), is an alternative autogenous material for patch angioplasty which preserves the continuity of the saphenous vein. A technique of incising endarterectomized segments of superficial femoral artery in a spiraled manner is presented which allows for the creation of long autogenous tissue patches. A spiral is drawn on the exterior of a harvested arterial segment which is either 1 cm, 7 mm or 5 mm in width. When incised along the spiral, the length of the resulting elliptical patch will be two, three, or four times, respectively, the length of the original artery segment. The authors have used the technique to close extended profundoplasty in three patients and for construction of a patched distal anastomosis in two patients undergoing prosthetic femoropopliteal bypass grafting. There have been no early complications.

Bioprosthesis↗
PubMed1995

Effect of sex class on nutrient content of meat from young goat.

The effect of sex class on proximate composition and cholesterol, vitamin, mineral, and fatty acid content was determined for carcass composite samples of cooked goat meat. Soft tissues (fat and lean) from dissection of one side of seven carcasses each for female, castrate, and intact male Florida native or F1 crosses of Florida natives with Nubian or Spanish goats were ground, formed into patties, and then broiled. Also, a leg slice was removed from the side not used for dissection, broiled, and then sampled for fatty acid determination. Broiled samples from female goats had lower (P = .04) moisture and higher (P = .03) fat and total calories than did samples from castrates and intact males. Sex class had no effect on cholesterol, vitamin, or mineral content of cooked goat meat. Broiled goat leg slices from intact males were lower (P = .005) in percentage of total saturated fatty acids and had a higher (P = .01) unsaturated to saturated fatty acid ratio than samples of broiled leg slices from females or castrates. Broiled goat meat had higher values for calcium, potassium, thiamin, and cholesterol than that reported in USDA Handbook 8 for cooked composite samples of beef or chicken. Also, broiled goat meat had lower total lipid, phosphorus, and vitamin B12 than composite values reported for beef. Other nutrients were similar to those reported for cooked composite samples of beef and chicken.

Animals↗
PubMed1995

Performance, carcass yield, and carcass quality characteristics of steers finished on rhizoma peanut (Arachis glabrata)-tropical grass pasture or concentrate.

Steers (n = 156) finished on rhizoma peanut (Arachis glabrata Benth.)-tropical grass pasture in Florida and slaughtered at Central Packing, Center Hill were compared with steers (n = 152) finished on a concentrate diet in Texas and slaughtered at Excel, Plainview. Average daily gain during the growing and finishing periods was lower (P < .001) for forage-finished steers (.49 and .94 kg/d, respectively) than for concentrate-finished steers (.78 and 1.33 kg/d, respectively). Forage-finished steers had less fat over the ribeye (8.3 vs 11.4 mm; P < .01), lighter hot carcass weight (280 vs 346 kg; P < .001), and smaller longissimus muscle area (70.8 vs 86.6 cm2; P < .001) than concentrate-finished steers. Yield grade was not different (2.7 vs 2.6; P > .10), but quality grade was slightly better (low Select vs mid Select; P < .01) for concentrate-finished steers. Lean color of forage-finished steers was darker (P < .001) and fat of forage-finished steers had a creamier color (P < .001), but carcasses were not discounted due to yellow fat color. Shear force values were higher (6.8 vs 4.0 kg; P < .001) for forage-finished than for concentrate-finished steers. Off-flavors were detected by trained sensory panelists in 36% of forage-finished and 14% of concentrate-finished carcasses, but all at barely detectable levels. This research indicates that steers can be finished on rhizoma peanut-tropical grass pastures, but with some reduction in quality grade relative to concentrate-finished steers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1992

Effect of feeding high-oleic-acid peanuts to growing-finishing swine on resulting carcass fatty acid profile and on carcass and meat quality characteristics.

A high-oleic-acid peanut breeding line was used in a study designed to determine the effects of feeding swine diets containing elevated levels of monounsaturated fatty acids as a means to increase the level of monounsaturates and total unsaturates in the resulting carcass fat. Forty-eight pigs were allotted to four treatments that consisted of corn-soybean meal diets that contained 1) high-oleic peanuts (HOP), 2) regular commercial peanuts (RP), or 3) canola oil (CO), each added at a dietary level to provide 10% added fat/oil, and 4) a control diet with no added fat/oil. The oil of HOP averaged 75% oleic acid vs 60% for CO and 53% for RP. The pigs were fed the experimental diets from 33 to 102 kg BW, after which all pigs were slaughtered. All three dietary oil sources resulted in increases (P < .01) of monounsaturates in the backfat; the HOP diet resulted in the greatest increase (32% greater than control). Both CO and RP increased (P < .01) the level of polyunsaturates by nearly twofold; HOP resulted in a small decrease. Total unsaturates increased (P < .01) by 24, 24, and 27% for HOP, RP, and CO treatments, respectively, over that obtained from the control treatment. Carcass fat was softer/oilier (P < .05) from pigs fed CO and RP diets, but not from those fed HOP diets, compared with carcass fat of pigs fed the control diet. Dietary fat/oil source had no effect (P > .05) on other carcass compositional traits and various meat quality attributes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1992

The True Daylight Illuminator (TDI): a less expensive source of illumination for color vision screening.

This experiment was designed to examine the feasibility of using the True Daylight Illuminator (TDI) as an illumination option for conducting color vision screening with the Ishihara Test(s). The MacBeth Easel Lamp was designed to provide proper illumination for performing color vision screening with a variety of pseudoisochromatic (PIC) plate tests including the Ishihara. However, over the years, the MacBeth Lamp has become so expensive that many smaller programs cannot afford to purchase one. This problem has promoted the use of alternate light sources that have had a deleterious effect on test results and in some instances contributed to job discrimination. Recently the MacBeth Division of the Kollmorgan Corporation discontinued the manufacture of the MacBeth Lamp due to lack of demand. Thus, it is important to find an inexpensive illumination option for conducting color vision screening. Two groups of subjects were used to compare test results for the 24-plate edition of the Ishihara Test using both the MacBeth Lamp and the True Daylight Illuminator. The first group contained 45 subjects with inherited color defective vision. The second group was made up of 30 color normals. The Nagel anomaloscope was used to confirm the color vision status of the subjects in both groups. Statistics to test the significance of differences between group means clearly demonstrated that there were no significant differences between the mean error scores of the two groups for these two pieces of equipment. Thus, it was concluded that the TDI can be used in lieu of the MacBeth Easel Lamp for screening color vision with the Ishihara test.

Adolescent↗
PubMed1992

The Ishihara Test: on the prevention of job discrimination.

Experiments were carried out to answer questions relative to the use of the 24-plate edition of the Ishihara Test for Colour-Blindness as a screening instrument for detecting the presence of inherited color defective vision. Subjects and their numbers varied between some experiments. Some subjects had normal color vision and others had inherited color defectiveness as confirmed with a Nagel anomaloscope. Most of the 157 subjects who participated in the experiments were either young deaf college students or police recruits with normal hearing who did not pass the Ishihara Test during their respective visual screening processes. Some hearing faculty and staff participated as part of Experiment 2. Item analysis and statistics applied to test the significance of differences between group means were applied to derive the following results: (a) test-retest reliability for the Ishihara is high both for persons with inherited color defectiveness and normal color vision; (b) persons making fewer than five errors on the first 13 plates made common incidental (nontypical) errors not related to color defective vision; and (c) five (5) or more errors was identified with some degree of inherited color defective vision, and subsequent referral for additional color vision diagnostics is warranted. Failure to utilize the recommended "pass-fail" criterion and/or to allow clients who fail color vision screening recourse to additional testing to establish type and degree of color defective vision may unnecessarily lead to job discrimination and/or interfere in a negative manner with the career selection process.

Adolescent↗